FINAL REPORT
BASELINE METEOROLOGY AND AIR QUALITY
IN THE UKIAH DISTRICT
scieNce ApplicanoNS, inc.
Jfc 6~ IrW
BUREAU OF LAND MANAGEMENT
m
V, /
FINAL REPORT
BASELINE METEOROLOGY AND AIR QUALITY
IN THE UKIAH DISTRICT
Submitted to:
Bureau of Land Management
Sacramento, California
Prepared by:
W. P. Lynott
D. Rykaczewski
J. Rodell
H. Frentz
D. Cover
February 22, 1980
147
Denver, Colo; <
Center
JD
SCIENCE APPLICATIONS, LA JOLLA, CALIFORNIA
ALBUQUERQUE • ANN ARBOR • ARLINGTON . ATLANTA . BOSTON • CHICAGO • HUNTSVILLE
LOS ANGELES • McLEAN . PALO ALTO • SANTA BARBARA. SUNNYVALE • TUCSON
P.O. Box 2351. 1200 Prospect Street, La Jolla, California 92037
TABLE OF CONTENTS
Section Page
1. INTRODUCTION 1
2. PHYSICAL FEATURES 7
3. CLIMATOLOGY 13
3.1 PRINCIPLES OF CLIMATOLOGY 13
3.2 CLIMATIC ZONES 24
3.3 SOURCES OF CLIMATOLOGICAL DATA 27
3.3.1 Observations and Records 27
3.3.2 Climatological Data 28
3.4 TEMPERATURE 32
3.4.1 Mean Temperature Distribution 37
3.4.2 Temperature Extremes 40
3.4.3 Frost-Free Period 41
3.5 PRECIPITATION 44
3.5.1 Annual Distribution 44
3.5.2 Seasonal Precipitation 46
3.5.3 Snowfall 48
3.5.4 Precipitation Frequency 53
3.6 PREVAILING WINDS 56
3.6.1 Annual Wind Distribution 56
3.6.2 Seasonal Wind Distribution 60
3.7 EVAPORATION AND RELATED PARAMETERS 64
3.7.1 Evaporation and Evapotranspiration 64
3.7.2 Sky Conditions 67
3.7.3 Solar Radiation 75
3.8 OTHER CLIMATIC PARAMETERS 79
3.8.1 Relative Humidity and Dew Point 79
3.8.2 Severe Weather 80
3.8.3 Atmospheric Pressure 93
3.8.4 Visibility and Fog 98
3.8.5 Ocean Temperatures 108
3.9 URBAN EFFECT UPON METEOROLOGIC PARAMETERS Ill
3.10 GENERAL ASSISTANCE IN CLIMATIC PROBLEMS 115
3.11 GLOSSARY OF TERMS 115
TABLE OF CONTENTS
(Cont.)
Section Page
4. DISPERSION METEOROLOGY 131
4.1 INTRODUCTION 131
4.2 PRINCIPLES OF DISPERSION METEOROLOGY 133
4.2.1 Principles of Turbulence and Diffusion 133
4.2.2 Prevailing Winds 139
4.2.3 Atmospheric Stability 146
4.2.4 Mixing Heights and Inversions 155
4.2.5 Influence of Topography on Transport and Diffusion . . 156
4.3 DATA SOURCES 168
4.4 PREVAILING WINDS 172
4.4.1 Wind Roses 172
4.4.2 Diurnal Wind Distribution 182
4.4.3 Wind Speed Distribution 184
4.4.4 Persistence Analyses 193
4.4.5 Trajectory Analyses 194
4.4.6 Winds Aloft 194
4.5 ATMOSPHERIC STABILITY 198
4.5.1 Seasonal and Annual Stability Distributions 198
4.5.2 Diurnal Stability Distributions 204
4.5.3 Stability Persistence 207
4.5.4 Stability Wind Roses 207
4.6 MIXING HEIGHTS AND INVERSIONS 212
4.6.1 Mixing Height 212
4.6.2 Inversion Types and Frequencies 219
4.7 TYPICAL AND WORST-CASE CONDITIONS 223
4.7.1 Typical Dispersion Conditions 223
4.7.2 Worst-Case Dispersion Conditions 223
4.8 AIR BASIN ANALYSIS 228
4.9 FIRE WEATHER 232
4.10 GENERAL DISPERSION MODELING 239
4.10.1 Classes of Models 239
4.10.2 Model Suitability and Application 240
4.10.3 The Gaussian Model 242
4.11 ASSISTANCE IN DISPERSION METEOROLOGICAL PROBLEMS 270
4.12 GLOSSARY OF TERMS 272
TABLE OF CONTENTS
(Cont.)
Section Page
5. BASELINE AIR QUALITY EMISSION LEVELS 284
5.1 FORMATION OF AIR POLLUTANTS 284
5.1.1 Introduction 284
5.1.2 The Gaseous Compounds of Carbon 284
5.1.2.1 The Hydrocarbons 290
5.1.2.2 The Oxygenated Hydrocarbons 290
5.1.2.3 The Oxides of Carbon 295
5.1.3 The Gaseous Compounds of Sulfur 304
5.1.3.1 The Sulfur Oxides 304
5.1.3.2 Reduced Sulfur Compounds 307
5.1.4 The Gaseous Compounds of Nitrogen 309
5.1.4.1 The Oxides of Nitrogen 309
5.1.5 Ozone and Oxidants 316
5.1.6 Particulate Matter 318
5.1.7 Atmospheric Chemistry of Air Pollution 321
5.2 AIR POLLUTION EFFECTS ON AIR QUALITY RELATED VALUES 327
5.3 BASELINE AMBIENT AIR QUALITY 353
5.4 POINT AND AREA SOURCES OF THE UKIAH DISTRICT 368
5.5 ASSISTANCE IN AIR POLLUTION PROBLEMS 377
5.6 GLOSSARY OF TERMS 384
6. AIR QUALITY REGULATIONS 400
6.1 EXECUTIVE SUMMARY 400
6.1.1 Background 400
6.1.2 Permit Rules for New or Modified Sources 401
6.1.2.1 Nonattainment Areas 401
6.1.2.2 Attainment Areas and Prevention of
Significant Deterioration Review 401
6.1.2.3 Role of the Federal Land Manager in the
Permit Review Process 402
6.1.2.4 Role of the Federal Land Manager in
Class Redesignation Procedures 404
6.1.3 Visibility Protection 404
6.1.4 Emission Standards 404
6.1.5 State Regulations 405
6.1.5.1 Permit Rules 405
TABLE OF CONTENTS
(Cont.)
Section Page
6.2 THE ROLE OF THE FEDERAL LAND MANAGER 406
6.3 HISTORY OF AIR QUALITY LEGISLATION 407
6.4 SUMMARY OF THE CLEAN AIR ACT AMENDMENTS OF 1977, AND
RELATED REGULATIONS 410
6.4.1 National Ambient Air Quality Standards (NAAQS) ... 410
6.4.2 Designation of Attainment Status 410
6.4.3 State Implementation Plans 411
6.4.3.1 Nonattainment Areas 411
6.4.3.2 Attainment Areas 412
6.4.4 Visibility Protection 424
6.4.5 Ozone Protection 426
6.5 STATE AND COUNTY REGULATIONS 427
6.5.1 State Ambient Air Quality Standards 427
6.5.2 County Regulations 427
6.5.3 Permit Rules 430
6.5.3.1 Description of Model Rule/Districts'
Rules 430
6.5.3.2 California's Air Conservation
Program (ACP) 431
6.5.3.3 Emission Regulations 432
6.5.3.4 Burning Regulations 440
6.6 GLOSSARY OF TERMS 448
7. MONITORING RECOMMENDATIONS 454
7.1 GENERAL REQUIREMENTS 454
7.2 INSTRUMENTATION 457
7.2.1 General Requirements 457
7.2.2 Meteorological Instruments 460
7.2.3 Air Quality Instruments 473
7.2.3.1 Particulates 473
7.2.3.2 Continuous Gas Analyzers 477
7.2.4 Monitoring Program Operation 482
7.3 UKIAH DISTRICT MONITORING REQUIREMENTS 492
7.4 GLOSSARY OF TERMS 496
TABLE OF CONTENTS
(Cont.)
APPENDIX A - ISOPLUVIAL OR RAINFALL INTENSITY ANALYSES OF CALIFORNIA
APPENDIX B - MONTHLY SEA SURFACE TEMPERATURES OFF COASTAL CALIFORNIA
APPENDIX C - SEASONAL AND ANNUAL MIXING HEIGHTS DURING THE MORNING AND
AFTERNOON HOURS IN THE CONTIGUOUS UNITED STATES
APPENDIX D - BASELINE AIR QUALITY IN THE UKIAH DISTRICT
APPENDIX E - LONG-TERM BASELINE AIR QUALITY IN THE UKIAH DISTRICT
APPENDIX F - 1976 - EMISSIONS DATA FOR THE UKIAH DISTRICT POINT SOURCES
APPENDIX G - 1976 - EMISSIONS DATA FOR THE UKIAH DISTRICT AREA SOURCES
APPENDIX H - SUMMARY ANALYSIS - UNITED STATES COURT OF APPEALS, D. C. CIRCUIT
JUNE 18, 1979 DECISION - ALABAMA POWER COMPANY, ET AL. V. USEPA ET AL.
1. INTRODUCTIOI
This document provides baseline data on meteorology and
air quality impacting BLM lands in California, and specifically,
in. the Ukiah District. Air quality considerations have become
important factors in the establishment and execution of Federal
land management policies. As with any resource, an assessment of
current air quality and meteorological data must be performed to
determine the present environmental baseline conditions.
BLM manages approximately 16.5 million acres in Cali-
fornia as depicted in Figure 1-1. Figure 1-2 depicts BLM admin-
istered lands in the Ukiah District. Figure 1-2 is also provided
as Overlay A. In addition, gridded township and range locations
for the Ukiah District are provided on Figure 1-3. This map can
be used directly with the color coded overlays provided for key
parameters .
The purpose of this document is to provide information
which can be used with other resource information to facilitate
land use planning decisions for the Ukiah District.
f ol 1 owi ng
The specific objectives of this work effort include the
Describe the climatology, dispersion meteorology
and air quality in the Ukiah District utilizing
available historical data.
Assess the
1 and area s
emission sources which influence all
in the Ukiah District.
BLM
• Assess past and present air quality and meteor-
ological monitoring activities and provide mon-
itoring recommendations for the Ukiah District.
• Provide a complete bibliography of available infor-
mation and a glossary of all technical terms.
The above provides a brief synopsis of the objectives of this
report. The document is intended for use by BLM personnel in all
activities involved in the management of BLM administered lands.
This document uses a graphics intensive approach in the
presentation of the meteorological and air quality baseline for
BLM lands in the Ukiah District. The data base which has been
used to develop this document comprises that available in pub-
lished form from governmental, academic, and private institutions
within the state. These sources of data are summarized in the
appropriate sections for dispersion meteorology, climatology, air
quality, and emissions.
Figure 1-1
BLM Lands in the Ukiah District
and the State of California
CRESCENT /*
CITY \
DEL NORTE
60
-I
MILES
BUREAU OF LAND
MANAGEMENT DOMAIN
MENDOCINO
LAKE
COLUSA
UKIAH* UT^A^^nr^T
LJ YV/LAKE P0RT'
X SONOMA 'v£/L_
A/A] WOODLAND
,\ NAPAVJ. •
\ El W
ru\y/%, yol°
X^SANTA ROSA H?
^napaTsolano
11*
J J FAIRFIELD
) MARIN
SAN RAFAEL •
Figure 1-2
BLM Lands in the Ukiah District
60
SAN RAFAE
Figure 1-3
Gridded Township (N-S) and Range (E-W)
Locations in the likiah District
The report presents data which represent meaningful
(i.e., long-term) and representative time periods. The primary
climatic parameters such as temperature and precipitation are
based on a minimum of ten years of record and have been updated
through 1976. For the secondary climatic parameters, e.g. evap-
oration, shorter periods of record were used due to poor data
availability; however, the most recent available data are pre-
sented .
The dispersion meteorological analyses are based on five
or more years of data for the primary parameters, i.e., wind
speed, wind direction, atmospheric stability and mixing height.
The actual period of record varies for many stations depending
upon the period for which summarized data are available from the
National Climatic Center (NCC). In addition, other sources of
data which significantly contributed to the analysis were used
although these consisted of shorter periods of record.
Baseline air quality levels in the Ukiah District are
based on 1975 data, while frequencies of violations utilize 1977
information. Emissions data presented in the report are based
upon 1976 inventories. And finally, pollutant attainment status
analyses have incorporated the most recent 1979 decisions.
Data are presented in the text in a graphics intensive
manner with heavy dependence upon charts, tables, figures and
overlays. The purpose of this manner of presentation is to
facilitate the use of the data by BLM personnel. A key aspect of
the graphical approach includes the use of color coded overlays
for key parameters. Figures which depict conditions throughout
the Ukiah District are scaled such that they can be used in
conjunction with the overlays provided in the report jacket, in
order to better grasp the interactive nature of key parameters.
can
The
1 ang
pers
prov
hand
for
cl i m
i n t
ronm
grpu
i mpa
tail
i mpa
sis
The results of the analyses provided in this docu
be used by BLM personnel for a multitude of applicati
document has been written in straightforward and simpli
uage such that it can be used by all levels of BLM techn
onnel. A sufficient review of basic principles has
ided throughout the text such
book for training purposes,
making a first cut analysis
atological problems. In addition, the information conta
his document is suitable for use in the development of E
ental Statement sections. Some of the data provides b
nd information suitable for the environmental setting
ct sections. However, the reader is cautioned that a
ed analysis of major problem areas, such as the poten
ct of new pollutant sources, would require additional an
and analytical review beyond that contained in this docum
that it can also be used
It provides an excellent
for specific air quality
ment
ons .
stic
i ca 1
been
as a
base
and
i ned
nv i -
ac k-
and
de-
tial
aly-
ent .
Finally, in addition to its uses as a training handbook
and for use in Environmental Statements, this document can be
used for overall planning purposes by BLM land managers. This is
one of the major intents for publishing the document. It is felt
that the information contained herein will provide suitable
information on which one can base judgments relative to the
optimum utilization of BLM lands in terms of such potential
alternatives as agriculture, forest management and energy devel-
opment, as these relate to the air resource.
This report is intended as an environmental baseline
document suitable for use in the administration of BLM lands.
Recommendations have been provided in the text concerning the
need for additional data to adequately describe the environmental
baseline, i.e., air quality and meteorology in certain portions
of the Ukiah District. Monitoring would be required, as well as
additional analyses, prior to making final decisions relative to
major potential sources of air pollutants on BLM lands. Recom-
mendations contained in this document for additional data col-
lection and for additional analyses must be seriously considered
by BLM planners during any final decision-making process. In
addition, the information contained herein is current as of the
publication date, but care must be taken while using the docu-
ment, to ensure that all information and materials are up to
date, particularly with regard to air quality regulations. For
this reason, it is recommended that this document be updated on
an annual basis by qualified technical personnel.
Separate reports have also been prepared for the
Riverside, Redding, Susanville, Bakersfield and Fol som Districts.
Reference should be made to the appropriate reports for air
quality and meteorological baseline conditions for BLM lands
outside of the Ukiah District in California.
2. PHYSICAL FEATURES
The following discussion provides a review of the major
terrain and vegetation features in the Ukiah District. Ukiah is
comprised of numerous terrain and vegetation types as indicated
inthe accompanying figures. Elevations range from sea level to
over 7,000 feet above mean sea level (MSL) in the Siskiyou Moun-
tains. Vegetation types range from marshlands to Douglas Fir.
The major vegetation types as classified by Durrenberger
(1967) are depicted in Figure 2-1. This figure, illustrates the
variety of vegetation types found in the coastal and interior
mountainous regions. In coastal Northern California, vegetation
types primarily include Douglas Fir, fir and plains grass. The
mountainous portions of the Ukiah District are characterized by
fir and woodlands. The Central Valley area is primarily charac-
terized by plains grass and marshlands.
As indicated earlier, these vegetation types are dis-
tinctly influenced by terrain considerations. Figure 2-2 pro-
vides a review of major terrain features in the State of Cali-
fornia. Figure 2-3 illustrates the Ukiah District terrain. This
figure is also included as Overlay B.
The Ukiah District includes all or parts of eleven
counties which comprise the northwestern portion of the State of
California. The terrain of the District exhibits considerable
variation ranging from the coastline of Marin, Sonoma, Mendocino,
Humboldt and Del Norte Counties to the rugged terrain of the
Coast Ranges. Elevations rapidly increases with inland distance
from the Coast in all portions of the District with the exception
of the extreme south. In the extreme northwest, elevations
rapidly increase with rugged terrain in Del Norte and Siskiyou
Counties, particularly in the Siskiyou, and further inland, and
the Klamath Mountains. Some of the highest elevations in the
District are located in Del Norte and Siskiyou Counties in the
rugged terrain of the Six Rivers National Forest and further
inland in the Siskiyou National Forest. Further south in
Humboldt County the trend towards rugged terrain with inland
progression increases, however, elevations do not
idly. Elevations in most of the Humboldt County
between two and four thousand feet.
rise as ra p-
are generally
The northwest is drained by several
including the Klamath and the Eel Rivers,
inland extent of the District increases and
Lake, Colusa, Yolo, Solano, Napa, Sonoma and
District coastal areas traverses the Coast
portions of the Sacramento Valley in Colusa, Yolo and Solano
Counties. In Mendocino County, the trend exhibited further north
continues with the terrain becoming fairly rugged with inland
progression. However, elevations continue to decrease with most
elevations between one and three thousand feet. A major valley
maj or ri ver systems
Further south the
includes Mendocino,
Marin Counties. The
Ranges and i ncl udes
I Redwood
I Douglas Fir
mm Fir
[:'£•:';:] Pine-Douglas Fir-Fir
Pine
Lodgepole-l/Vhitebark Pine
|///n Pinon Pine— Juniper
Figure 2-1
Major Vegetation Types
in California
Source: "Patterns on the Land" Robert W. Durrenberger
8
ELEVATIONS
14495
Figure 2-2
California Topography
ELEVATIONS
ARCATA
6000
3000
1500
®
500
0
W. SACRAMENTO
Figure 2-3
Ukiah District Topography
10
system exists in the middle of Mendocino County along the drain-
age flow of the Russian River. This valley includes the city of
Ukiah, the district office for the Ukiah District. Lake County
includes much of the Coast Range and is the center of much geo-
thermal activity. Clear Lake is located in this county and is
the largest standing body of fresh water in the Uk i ah" Di str i ct .
La-ke County is characterized by rugged forested terrain in the
north with elevations approaching 7,000 feet in the Mendocino
National Forest. Southward progression in the County exhibits a
generally decreasing elevation. Sonoma and Marin Counties are
generally characterized by the valley floor of the Santa Rosa and
Petal urn a Rivers as well as the Pacific terminus of the Russian
River. Major cities located in the valley include Santa Rosa,
Novato and San Rafael. The mountains of Sonoma and Marin
Counties are generally characterized as low rolling hills with
elevations generally less than 2,000 feet. Napa county contains
the southern portion of the Coast Ranges. Further progression to
the south leads to the major break in the Coast Ranges in the
State of California through the San Francisco-Oakland area. Napa
Valley is the center of much wine activity and contains the
second largest standing body of water in the district, Lake
Berryessa. Finally, the eastern three counties of the Ukiah
District include Colusa, Yolo and Solano which are in the
Sacramento Valley with the exception of the extreme western
areas. These counties are characterized by relatively flat
terrain with slowly decreasing elevations reaching a minimum
along the Sacramento River.
Local terrain plays a major role in determining regional
climatology. Therefore, a properly scaled overlay (Overlay B)
displaying the Ukiah District topographic features is provided
with this report in order that terrain features can be compared
with averages (isopleths) of the important climatic parameters.
11
1. Du r r e n b er g er , Robert W._
Press Books, Palo Alto,
1967.
BIBLIOGRAPHY
Patterns
on the Land
California, Second
National
Printing,
12
3. CLIMATOLOGY
This section is designed to characterize the prevailing
climate of the Ukiah District as well as to describe the physical
processes that determine regional climate. Long-term manifes-
tations of weather are best described by regional -and local
an-alyses of the numerous climatic parameters, i.e., temperature,
precipitation, winds, evaporation and ev apotranspi rat i on , sky
conditions, dew point and humidity, pressure distributions,
severe weather and many others. The following sections shall
describe the various climatic statistics pertinent to the area .
Color coded overlays for selected key climatic summaries
are provided to facilitate the correlation of the primary cli-
matic variables in particular geographic areas. Much of the
enclosed graphical material is properly scaled to the overlay
dimensions.
3.1
PRINCIPLES OF CLIMATOLOGY
E nergy
The energy expended in atmospheric processes is orig-
inally derived from the sun. This transfer of energy from the
sun to the earth and its atmosphere is the result of radiational
heat by electromagnetic waves. The radiation from the sun has
its peak of energy transmission in the visible range (0.4 to 0.7
microns) of the electromagnetic spectrum but renergy in the
ultraviolet and infrared regions as well. The greatest part of
the sun's energy is emitted at wave lengths between 0.1 and 30
microns. Some of this radiation is reflected from the tops of
clouds and from the land and water surfaces of the earth. The
general term for this reflectivity is the albedo. For the earth
and atmosphere as a whole, the albedo is 36 per cent for mean
conditions of cloudiness over the earth. This reflectivity is
greatest in the visible range of wavelengths. When light (or
radiation) passes through a volume containing particles whose
diameter is smaller than the wavelength of the light, scattering
of a portion of this light takes place. Shorter wavelengths
scatter most easily, which is the reason the scattered light from
the sky appears blue. Sunlight, near sunrise and sunset, passes
through a greater path-length of the atmosphere and appears more
red because of the increased scattering of shorter wave lengths.
Absorption of solar radiation by some of the gases in the atmos-
phere (notably water vapor) also takes place. Water vapor,
although comprising only 3 per cent of the atmosphere, on the
average absorbs about six times as much solar radiation as all
other gases combined. Consequently, the amount of radiation
received at the earth's surface is considerably less than that
received above the atmosphere.
The earth also radiates energy in proportion to its
temperature according to Planck's law. Because of the earth's
temperature, the maximum emission is about 10 microns, which is
13
in the infrared region of the spectrum. The gases of the atmos-
phere absorb some wave length regions of this radiation. Water
vapor absorbs strongly between 5.5 and 7 microns and at greater
than 27 microns but is essentially transparent from 8 to 13
microns. Carbon dioxide absorbs strongly between 13 and 17.5
microns. Because the atmosphere absorbs much more of the terres-
trial radiation than solar radiation, some of the heat energy of
the earth is conserved. This is the "greenhouse" effect.
Figure 3.1-1 shows the amount of solar radiation absorb-
ed by the earth and atmosphere compared to the long wave radia-
tion leaving the atmosphere as a function of latitude. The sine
of the latitude is used as the abscissa to represent area. It
can be seen that if there were no transfer of heat poleward, the
equatorial regions would continue to gain heat and the polar
regions would continue to cool. However, temperatures do remain
nearly constant because of this poleward transfer of heat. The
required transfer of heat across various latitudes is given in
Table 3.1-1.
Table 3. 1-1
Required Flux of Heat Toward the
Poles Across Latitudes (10 calories per day) * '
Lc
1 1 i t u d e (
0
10
20
30
40
50
60
70
80
90
°)
Fl ux
0
4.05
7.68
10.46
11.12
9.61
6.68
3.41
0.94
0
1. Source: H. G. Houghton, "On the Annual Heat Balance of the
Northern Hemisphere."
The General Circulation
The previous section has indicated the necessity of
transfer of heat from the warm equatorial regions to the cold
polar regions in order to maintain the heat balance of the atmos-
phere. This thermal driving force is the main cause of atmos-
pheric motion on the earth. The portion of the earth near the
equator acts as a heat source and the polar regions as a heat
sink. The atmosphere functions as a heat engine transforming the
potential energy of heat difference between tropics and poles to
kinetic energy of motion which transports heat poleward from
source to sink.
14
tec
*X>
•OMTO* SO
/lANGim \
\ BTV }
>oc
A
•
\
\
m X 40 X »C K «C
tINl O' IATITU0I
A Solar Radiation Absorbed by Earth and Atmosphere
B Long Wave Radiation Leaving the Atmosphere
Figure 3.1-1
Global Radiation Balance
15
tor
unt i
surf
defl
fore
and
erly
( zon
equa
and
Figu
i mpo
wi nd
lies
t i on
caus
t i on
and
the
heat
t ran
If the
would move
1 the time
ace current
ect s winds
flow from
flow from the
The resul t
earth did not rotate, rising air above the equa-
poleward continually giving up some of its heat
it would sink and return toward the equator as a
Since the earth does rotate, the Coriolis force
in the northern hemisphere to the right. There-
the tropics toward the poles become more westerly
poles toward the equator tends to become east-
is that more of the motion is around the earth
al ) with less than one-tenth of the motion between poles and
tor. The meridional (along meridians, i.e., between poles
equator) circulation is broken into three cells shown in
re 3.1-2 according to Palmen's (1951) model. Of considerable
rtance is the fact that the jet stream (i.e., a core of high
s usually 50 miles per hour or more embedded in the wester-
in the high troposphere) does not remain long in one posi-
but meanders and is constantly changing position. This
es changes in the location of the polar front and perturba-
s along the front. The migrating cyclones (counterclockwise)
anticyclones (clockwise) resulting, play an important part in
heat exchange, transferring heat northward both as a sensible
and also latent heat. Also, a small amount of heat is
sferred poleward by the ocean currents.
Temperature
Variation with Height
In the lower region of the atmosphere extending from the
surface to about 2 km. (6600 ft.), the temperature
distribution varies considerably depending upon the
character of the underlying surface and upon the amount
of radiation at the surface. Within this region, the
temperature may decrease with height or it may actually
increase with height (inversion). This region, commonly
called the lower troposphere, is the region of greatest
interest in air pollution meteorology. The remainder of
the troposphere is typified by a decrease of temperature
with height on the order of 4 to 8 C per km. The strat-
osphere is a region with isothermal or slight inversion
lapse rates. The layer of transition between the tro-
posphere and stratosphere is called the tropopause. The
tropopause varies in height from about 8 to 20 km
(26,000 to 66,000 ft.), and is highest near the equator,
lowest near the poles. Figure 3.1-3 and 3.1-4 indicate
typical temperature variations with height for two
latitudes for summer and winter in the troposphere and
1 ower stratosphere .
Above the stratosphere, the high atmosphere has several
layers of differing characteristics. A rough indication
of the variation of temperature with height including
the high atmostphere is shown in Figure 3.1-5.
16
JOlAI TIOPOPAUSt
fOLAl FIONT JET
TtOPICAL
THOPOPAUSE
Figure 3.1-2
General Circulation Model (after Palmen)
17
23
IS —
HEIGHT
(KM.) 10 t—
• •0
.40 -20 0
TtMHtATUlf {*C)
VAtkMON Of TlMKfcATUK WITH HltCHT AT 3D* NOtTM CATfTVOC
Figure 3.1-3
MCICHT
<KM.)
20
IS
10
UMMfl —
••0 -60 .40 -20 0
TlMfflATUlC (*C»
20
VAIUTOH Of TlMKtATUM WITH HIICMT AT «0» NOMH UTITVW
Figure 3.1-4
18
Horizontal Variation
Temperature also varies horizontally particularly with
latitude, being colder near the poles and warmer near
the equator. However, the influence of continents and
oceans have considerable effects on modifying tempera-
tures. The continents have more extreme temperatures
(continental climate) becoming warmer in summer and
colder in winter, whereas the oceans maintain a more
moderate temperature (marine or maritime climate) year-
round .
Winds
Wind is nothing more than air in motion and although it
is a motion in three dimensions, usually only the horiztontal
component is considered in terms of direction and speed. In the
free atmosphere (above the effects of the earth's friction), two
forces are important. The first, the Coriolis force, is due to
the tendency for the air to move in a straight path while the
earth rotates underneath thereby deflecting the wind to the right
in the northern hemisphere and to the left in the southern hemis-
phere. The deflection is proportional to the wind velocity, and
decreases with latitude. The other force affecting the horizon-
tal wind component is the pressure gradient force, which directs
flow from high to low pressure. Above the friction layer, in re-
gions where the lines of constant pressure (isobars) are straight
and the latitude is greater than 20°, the two forces are in
balance (See Figure 3.1-6) and the wind blows parallel to the
isobars. Where isobars are curved, the forces are not in bal-
ance, their resultant producing a centripetal acceleration. In
:he lowest portion of the atmosphere frictional drag (not due to
but to eddy viscosity) slows down the wind
the Coriolis force is proportional to the wind
Coriolis force. The balance of forces under
shown in Figure 3.1-7. It will be noted that
under frictional flow the wind has a component across the isobars
toward lower pressure.
molecular friction
speed , and beca use
s peed , red uces the
frictional flow is
Anticyclones and Cyclones
Migrating areas of high pressure (anticyclones) and low
pressure (cyclones) and the fronts associated with the latter are
responsible for the day to day changes in weather that occur over
most of the mid-latitude regions of the earth. The low pressure
systems in the atmospheric circulation are related to perturba-
tions along the jet stream (the region of strongest horizontal
temperature gradient in the upper troposphere and consequently
the region of strongest winds) and form along frontal surfaces
separating masses of air having different temperature and mois-
ture characteristics. The evolution of a low pressure system is
accompanied by the formation of a wave in the circulation pat-
tern. This develops further into a warm front and a cold front
both moving around the low in a counterclockwise (cyclonic)
19
»«
IB
MO
• I 1 » T T" 1 t
Ainruof
» .
ONOt*«(
TtMMIATUM (*K)
SO
Figure 3.1-5
General Variation of Temperature with Height Throughout
the Atmosphere
LOW
C«A.OKNT K»Cf
1
>
GfOSTtO^HC
WIN&
<
■
COtOltS
K)tCE
MICH
r - 2
» • i
UJ
low
FE&slwi
OAAOKNT KStCf
♦ WIMC
WICTlON L^^""*"^
ETON ♦ i^ FOtCt
«KTON ♦ ♦• *OtCI
COtOLB POtCE
MICH
r - J
r - i
r ♦
Figure 3.1-6
Balance of Forces in
the Upper Atmosphere
Figure 3.1-7
Balance of Forces in the
Lower (Friction Layer) Atmosphere
20
sense. The life cycle of a typical cyclone is shown in Figure
3.1-8. The cold front is a transition zone between warm and cold
air. The cold air typically is moving toward and over the area
previously occupied
si opes from 1/50 to
air from retreating
1/-100 to 1/300 due
edge of the front .
sect ion through both
Air Masses
by warm air. Cold fronts generally have
1/150. Warm fronts separate advancing warm
cold air and have slopes on the order of
to the effects of friction on the trailing
Figure 3.1-9 illustrates a vertical cross
a warm and a cold front.
Air masses are frequently divided by frontal systems and
are usually classified according to the source region of their
recent history. Air masses are classified as maritime or conti-
nental to indicate origin over the ocean or land, and arctic,
polar, or tropical depending principally on the latitude of
origin. Air masses are modified by vertical motions and radia-
tion upon the surfaces over which they move.
Condensation, Clouds, and Precipitation
Condensation of water vapor upon suitable condensation
nuclei in the atmosphere causes clouds. (Table 3.1-2 indicates
the relative sizes of different particles.) Large hygroscopic
nuclei wil condense water vapor upon them even before saturation
as opposed to crystallization nuclei which promote
of ice crystals, at the expense of small water drop-
a supercooled cloud. Of course, only a small propor-
clouds produce rain. It is necessary that droplets
size so that they will have appreciable fall velocity
prevent complete evaporation of the drops before they
reach the ground. Table 3.1-3 indicates the distance of fall for
different size drops before evaporation occurs. Growth of water
droplets into rain drops large enough to fall is thought to
originate predominately with the large condensation nuclei which
grow larger as they fall through the cloud. The presence of an
electric field in clouds generally promotes the growth of rain-
drops.
i s reached ,
the growth
lets within
t i o n of all
increase in
and al so to
Particles
Table 3. 1-2
Sizes of Particles
Size (microns)*
Smal 1 ions
Medium ions
Large ions
Aitken nuclei
Smo ke , ha ze , d ust
less than 10
-3
10"3 to 5 X 10~2
5 X 10"2 to 2 X 10"1
5 X 10
10"1 to 2
to 2 X 10
-1
21
Figure 3.1-8
Idealized Development of a Low-Pressure (cyclone) System
22
F»Om sm
" U F10M S
2,
Cross Section Through a Cold Front
and a Warm Front
Figure 3.1-9
Key:
Ci
- Cirrus
Cb -
■ Cumulonimbus
Cs
- Cirrostratus
Ns ■
- Mimbostratus
Cu
- Cumulus
Sc -
- Stratocumulus
Ac
- Altocumulus
As ■
- Altostratus
23
Particles
Table 3. 1-2 (cont'd)
Si zes of Particles
Size (microns)*
Large condensation nuclei
Giant condensation nuclei
Cloud or fog dropl et s
Drizzle drops
Rai ndrops
2 X 10"1 to 10
10 to 30
1 to 100
100 to 500
500 to 4000
*1 Micron = 3.94 X 10
-5
inches
Tabl e 3. 1-3
Distance of Fall Before Evaporation (Findeison 1939)
Radius (microns)* Distance of Fall
1
10
100
1000
2500
1.3 x 10" inches
1.3 i nc hes
492 feet
2 6.1 miles
174 miles
*1 Micron = 3.94 X 10
-5
inches
3.2
CLIMATIC ZONES
California encompasses a vast amount of territory and
offers a wide variety of climate types, ranging from hot, arid
desert climates to cold, moist mountain climates. It is there-
fore advantageous to present the climatic analysis in terms of
climatic zones. Figure 3.2-1 depicts the general climatic zones
for California in each of the six BLM districts. Overlay C
presents the climatic zones for the Ukiah District,
topography as well as latitude plays a major role in
mi nation of the characteristic climate of the various
regions .
Reg ion a 1
the deter-
C a 1 i f o r n i a
The Ukiah District is comprised of a complete cross-
section of the various types of topographic features present in
California as described in Section 2 and includes three of the
24
LEGEND:
S5&S COASTAL
^Mm COASTAL MOUNTAIN
CENTRAL PLAIN
#&>] INTERIOR MOUNTAIN
N.E. MOUNTAIN
DESERT
-.r=z^rZ RIVERSIDE- .. needles
— DISTRICT -
SAN BERNARDINO— -
..=■■ PARKER DAM
LOS ANGE
li^j&;v:~-;V-RIVERSIDE •:%?»: r:.jz. r — I
Figure 3.2-1
California Climatic Zones
BLYTHE
OCEANSIDE
..-• ' '_:'- EL CENTRO
SAN DIEGOi#;
25
major climatic subdivisions or zones existing in the State.
These include the Coastal, Coastal Mountain and Central Climatic
Zones ( CZ) .
The Coastal CZ includes most of the area between the
coastline and the various coastal ranges below elevations of
approximately 1500 feet MSL. The Coastal CZ experiences a dis-
tinctly maritime climatic regime which is characterized by
substantial annual precipitation, a modest range in the average
and diurnal temperatures and fairly strong onshore winds. In
California, the Coastal CZ also experiences a Mediterranean style
climate with a distinct winter rainy season.
The Coastal Mountain CZ experiences similar climatic
conditions to those at lower coastal elevations. However,
throughout the Coastal and Coastal Mountain CZ's, local terrain
features play a distinct role in determining winds speeds as well
as wind direction. Rainfall tends to be more variable depending
upon the exposure of the higher terrain and the associated oro-
graphic enhancement or suppression of precipitation amounts.
Westward facing slopes experience increased rainfall while east-
ward or leeward facing terrain experiences a distinct "rain-
shadow" effect with lower rainfall amounts. Temperatures at
higher elevations tend to be more variable than those along the
immediate coastline. Finally, wind speeds tend to be higher in
mountainous regions and become less influenced by local effects
at the highest levels.
The southeastern portion of the Ukiah District comprises
a part of the Central Plain CZ. While some variability exists in
terms of climatic conditions across this area, the region is
generally characterized by modest rainfall and larger seasonal
and diurnal temperature ranges. The observed differences in the
annual climate in the Central Plain CZ are largely a function of
latitude although this portion of the district is fairly small
with only modest climatic differences. The climatic variability
observed within this small portion of Ukiah District is due
largely to proximity to the major break in the Coastal Ranges in
the San Francisco - Oakland area commonly known as the Carquince
Straits. Temperatures tend to be more moderate, precipitation
amounts greater and winds stronger in the southern portion of the
Central Plain CZ within the Ukiah District due to the maritime
influence exhibited in this region. On a typical summer day,
Vallejo and Benicia will be considerably cooler than Williams
located some eighty miles to the north.
Latitude also plays an very important role in
determining the local climate throughout the State of California.
Areas located to the north experience a higher frequency of
migratory storm systems during the winter season and hence,
heavier rainfall. This is also the case within the Ukiah
District with Eureka and Crescent City receiving considerably
more rainfall than Santa Rosa and San Rafael located further to
the south .
26
3.3
SOURCES OF CLIMATOLOGICAL DATA
It is necessary in the consideration of most climato-
logical problems to obtain meteorological information. Frequent-
ly, a special observational program must be initiated as will be
discussed in more detail in Section 7. However, there are also
many situations where current or past meteorological records from
a Weather Service station will suffice. The following outline
provides a brief insight into the types of observations taken at
Weather Service stations and some of the summaries compiled from
this data. The discussion also serves to describe the bulk of
the published data sources used in the Ukiah District analysis.
Many other data sources used in this report are noted in the
bibliography as appropriate.
3.3.1
Observations and Records
Surface
First Order Stations
There are 100 Weather Bureau stations where 24 hourly
observations are taken daily. The measurements taken
are: dry bulb temperature and wet bulb temperature (from
which dew point temperature and relative humdity are
calculated), pressure, wind direction and speed, cloud
cover and visibility. These observations are trans-
mitted each hour on weather teletype circuits and are
entered on a form with one day to each page. The orig-
inal is sent to the National Climatic Center (NCC) in
Asheville, North Carolina, and a duplicate is maintained
in the station files. Each station also maintains a
cl imatol og i cal record book where certain tabulations of
monthly, daily, and hourly observations are recorded.
Second Order Stations
These stations usually take hourly observations similar
to the first order stations above but not throughout the
entire 24 hours of the day.
Military Installations
Many military installations, especially Air Force Bases,
take hourly observations. These are transmitted on
military teletype circuits and therefore not available
for general use. No routine publications of these data
is done. Records of observations are sent to NCC where
special summaries can be made by use of punched cards.
Supplementary Airways Reporting Stations
These stations are located at smaller airports. Obser-
vations are not taken at regular intervals, usually
being taken according to airline schedules. These
observations are not published and are not available on
punched cards. Original records, however, are sent to
the NCC.
27
Cooperative Stations
Ther
most
take
mini
are
orig
cl i m
CI im
stat
data
v at i
are
meas
e are about 10,000 of these stations manned, for the
part, by volunteer observers. The observations are
n once each day and consist generally of maximum and
mum temperatures and 24 hour rainfall. Otrservat i on s
recorded on a form with one month to a page. The
carbon sent to the state
i nal is sent to NCC , a
atologist (prior to the
atologist Positions), and
ion. A few cooperative
on evaporation and wind,
ons are taken only a few
termination of the State
a carbon maintained at the
stations have additional
However, the wind obser-
inches off the ground and
of use mainly
urement s .
in connection with the evaporation
Fire Weather Service Stations
There are a number of special stations maintained during
certain times of the year in forested regions where
measurements of wind, relative humidity, and cloud cover
are taken. These are generally not on punched cards nor
are they summarized.
Upper Air
There are between 60 and 70 stations in the contiguous
United States where upper air observations are taken twice daily
(at 0000 GMT and 1200 GMT) by radiosonde balloon and radio direc-
tion-finding equipment. The measurements taken include tempera-
ture, pressure, relative humidity and wind speed and direction at
several levels. These observations are transmitted to teletype
and original records are sent to NCC where these data are pub-
lished. Since these data are collected primarily to determine
large scale meteorological patterns and have relatively little
refinement in the lower 2 to 3 thousand feet of the atmosphere,
they are of limited use in air pollution meteorology.
3.3.2
Cl imatol og i cal Data
There are a number of routine and special publications
available from the Superintendent of Documents, U.S. Government
Printing Office, Washington, D.C., 20402, that are useful in air
pollution evaluation. A number of these are listed in Price List
48, available from the Superintendent of Documents.
Routinely Prepared Data
• Daily Weather Maps - Weekly Series
The charts in this 4-page, weekly publication are a
continuation of the principal charts of the former
Weather Bureau publication, "Daily Weather Map." All of
the charts for 1 day are arranged on a single page after
being copied. They are copies from operational weather
maps prepared by the National Meteorological Center,
28
National
presents
EST.
Weather Service. The Surface Weather Map
station data and the analysis for 7:00 a.m.
The 500-Millibar Height Contour chart presents the
height contours and isotherms of the 500-millibar sur-
face at 7 : 00 a.m. EST .
The Highest and Lowest Temperatures chart presents the
maximum and minimum values for the 24-hour period ending
at 1:00 a.m. , EST.
The Precipitation Areas and Amounts chart indicates by
means of shading, areas that had precipitation during
the 24 hour period ending at 1:00 a.m., EST.
Local Climatological Data (LCD)
These data are published individually for each station
and include 3 issues discussed below.
Monthly Issue LCD
This issue gives daily information on a number of mete-
orological variables and monthly means of temperature,
heating degree days, pressure and precipitation. Also
tabulated are observations at 3-Hourly Intervals (obser-
vations for each hour of the day were discontinued after
December 31, 1964). This publication is usually avail-
able between the 10th and 15th of the following month.
LCD Supplement (monthly)
This issue is available for stations having 24 hourly
observations daily until December 31, 1964 when pub-
lication was discontinued. For air pollution investi-
gations, Tables B, E, F, and G would be of greatest
interest (Frederick, 1964). The Supplement is usually
available from 20 to 40 days after the end of the month.
LCD with Comparative Data (annual)
This issue, published annually, has a table of clima-
tological data for the current year and a table of
normals, means, and extremes for a longer period of
record. This issue is usually available between 45 and
60 days after the end of the year.
Northern Hemisphere Data Tabulations
This publication, issued daily, contains approximately
30 pages of surface synoptic observations and upper air
observations. The surface data are for one hour only
(1200 GCT). In this publication, the radisonde infor-
mation is of principal interest in air pollution mete-
orol ogy.
Climatological Data - National Summary
This publication of approximately 50 pages, issued
monthly, contains a narrative summary of weather
29
conditions, climatological data (similar to those given
in each station's LCD) in both English and metric units,
mean monthly radiosonde data, and solar radiation data.
Also included are a number of maps of the United States
showing spatial distribution of temperature, precipita-
tion, solar radiation and winds. The mean "radiosonde
and solar radiation data are of main interest in this
publication for air pollution meteorology.
Climatological Data (by State)
This summary , issued monthly and annually, contains data
primarily on temperature and precipitation. This will
provide only limited information to the air pollution
meteorologist.
Selected Climatic Maps
This publication consists of 30 U.S. maps of various
meteorological parameters such as: maximum and minimum
temperature, heating and cooling degree days, precipita-
tion, relative humidity, solar radiation, and surface
wind roses for January and July together with the annual
wind rose. Wind data are presented for 74 locations
within the contiguous U.S. A list of the basic Climatic
Maps from which the generalized maps of this publication
are taken is included.
Summar i es
Summary of Hourly Observation
This series of publications, Climatography of the United
States, No. 82-, Decennial Census of United States
Climate, has been prepared for over 100 Weather Bureau
stations where 24 hourly observations are recorded. One
issue is prepared for each station, and where the period
of record is sufficient, the ten year period 1951 - 1960
has been considered. For other stations, the 5 year
period 1956 - 1960 has been summarized. This series
supersedes the series, "Climatography of the United
States" No 30-, a 5 year summary published in 1956.
Climatic Guide
This series of climatological publications contains a
wealth of climatological information useful to the air
pollution meteorologist fortunate enough to have had one
prepared for his city. Of major interest to air pollu-
tion meteorologists, are tables of wind frequencies,
solar radiation and degree days.
Climatic Summary of the United S t a t e s - S u p p 1 erne nt for
1931 - 1952.
This summary, issued by state, contains tables of month-
ly and annual precipitation, snowfall, and temperature
for stations within the state.
30
Terminal Forecasting Reference Manual
This manual , publ i shed by stat i on , cTe scribes the weather
conditions at the station, and contains information on
local topography, visibility effects due to fog and
smoke, ceiling, precipitation, special weather occur-
rences, and mean wind and visibility conditions. Num-
erous charts are included summarizing the above ele-
ments. Of special interest are surface wind roses by
month and a wind rose chart related to restricted visi-
bility conditions. A topographic and smoke source map
for the station is included.
Key to Meteorological Records Documentation
Thi s series of publications was establ i shed to provide
guidance to those making use of observed data. A recent
addition to this series No. 4.11, "Selective Guide to
Published Climatic Data Sources prepared by U.S. Weather
Bureau" (1969) is extremely useful to anyone contemplat-
ing use of climatic data.
The series No. 1.1 title "Substation History" and issued
by state contains information regarding history of
station locations, type and exposure of measuring in-
struments, location of original meteorological records,
where published, and dates of first and last observa-
tions .
31
3.4
TEMPERATURE
Temperature is a critical climatological parameter for
land management activities. Temperature and related parameters,
such as the length of the growing season, greatly influence the
suitability of land areas for utilization in agriculture, forest-
ry and grazing.
Ambient temperatures are
factors, including the following:
determined by a multitude of
as
and
The intensity and duration of solar radiant energy
The degree of depletion of this energy by reflection,
scattering and absorption in the atmosphere
The surface a 1 bedo
The physical characteristics of the surface such
terrain types
The local heat budget in terms of terrestrial
atmospheric radiation
Heat exchanges involved in water phase changes
Importation or advection of warm or cold air masses
by horizontal air movement
Transport of heat upward or
currents caused by natural
ani cal t urbul ence
downward by vertical air
convection and/or mech-
In the United States, temperature is most commonly
measured in degrees Fahrenheit ( F), however, there is an in-
creasing trend towards the use of degrees Centigrade ( C). For
this reason, temperature data and analyses presented in this
report are in degrees Fahrenheit, with Table 3.4-1 providing a
summary of temperature conversion information for aid in the
usage of both systems.
Temperature data are available for numerous stations in
California. For this reason, key stations have been used to
represent the various climatic zones in the district in an effort
to limit the amount of data analysis necessary to present the
required information. Once again, the Ukiah District has been
divided into three key climatic zones in which temperature is
fairly homogeneous. For each of these regions, data from the
selected key stations has been used to describe temperature
characteristics. Data provided for each of the key stations
includes monthly and annual means, mean maximum, mean minimum as
well as the record high and low temperatures.
Figure 3.4-1 presents the three climatic zones super-
imposed on the district map with selected station locations for
which temperature data are available. Tables 3.4-2 through 3.4-4
summarize the temperature statistics for these stations in each
climatic zone. Section 3.2 briefly summarizes temperature and
other climatic characteristics of each climatic zone.
32
Table 3.4-1
TEMPERATURE CONVERSIONS
Temperature? in this publication are given in degrees Fahrenheit (°F) . The Celsius
(C) temperature scale, also called Centigrade, is used in most countries of the
world. A temperature conversion scale is shown on the left, note that the values
coincide only at the -40 degree mark.
°F
°C
i.
212 -
100
(Water
\ Boils
194
90
176
80
158
70
140
60
2.
134
rG7J U.S. Record
56-7>High
122
50
104
40
86 -
30
68 -
20
50
10
32
0
1.
( Water
\ Freezes
14
-10
-4
-20
-2?
-. -30
-40
-40
1 Scales
^Coincide
-58
-50
-76
-60
3.
( U.S. Record
-94
-70
\ Low
-112
-80
-130
-90
-148
- -100
The
°C
; standard formulas to convert
to °F are shown below:
°F to
°C and
op
= 9/5 °C h
• 32
°C
= 5/9 (°F
-32)
•
Atlernate, easy to remember conversion
fol low :
methods
°F
= 9/5 (°C
+ 40) -40
°C
= 5/9 (°F
+ 40) -40
To use the alternate conversion
converting from one scale to the
formulas for
other :
(a)
add 40 to the value to b
e converted
(bj
multiply
(5/9 for
(9/5 for
that sum by the
°F to °C)
°C to °F)
fract ion :
(c0
subtract
40 from the pro
duct
For exa
mple, to convert 68°F to
°C:
(a)
add 40:
68+40 = 108
(b)
multiply
5/9x108' =
the sum by 5/9
= 60
(°F to
°C) :
(c)
subtract
40: 60-40 = 20
(d)
answer :
68°F = 20°C
1. Under Standard Sea Level Pressure
2. Greenland Ranch, CA - July 10, 1913
3. Rogers Pass, Montana - January 20, 1954
33
JCRESCEN
fcn
COASTAL MOUNTAIN
CENTRAL PLAIN
SACRAMENTO
SANRA
Figure 3.4-1
Temperature Stations for the Ukiah District
34
(V
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s-
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3.4.1
Mean Temperature Distribution
sect
with
var i
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val u
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1 oca
1 ous
The data presented in 'the figures and tables in this
ion provide generalized information for BLM lands located
in each of the study regions. However, temperature is a
able which is subject to microclimatological effects and the
al temperature at a given location will depend upon several
ables as previously indicated. The data show that var iabili-
mong stations within a particular region is fairly modest and
the average values provided in the summary figures can be
with a good degree of confidence. Caution when using these
es is warranted when the location of interest varies signifi-
ly from the elevation of the key stations or if a particular
tion experiences important micro-scale effects (e.g., anoma-
ground cover conditions).
Annual Average
Figure 3.4-2 provides the mean annual temperature dis-
tribution for the Ukiah District and also appears as Overlay D.
The figure shows a modest 6°F range in mean annual temperature
across the region from a low of 54°F along most of the northern
coastal areas to a maximum of just over 60°F in the northeast
portion of the Central Plains CZ. Temperatures are uniform along
coastal locations showing the strong maritime influence of the
Pacific Ocean on ambient temperatures in this area. Temperatures
show very little variation with a gradual increase with inland
progression in the southern portion of the District. The de-
creased influence of the Pacific Ocean in the Central Plain
portion of the Ukiah District in the lee of the Coast Ranges is
evident from the somewhat increased mean annual temperatures.
Mean maximum and mean minimum temperature data are
summarized in Figures 3.4-3 through 3.4-5 for the three major
climatic zones in the Ukiah District on a monthly basis. The
influence of the Pacific Ocean on coastal and coastal mountain
temperature characteristics can be noted with the figures which
provide a comparison between the climatic zones. Coastal regions
experience a modest 15°F temperature increase from winter to
summer while Central Plain locations experience a 25°F differ-
ence .
Mean Maximum
During the months of December and January, maximum
temperatures range from the low 50's°F at Eureka to the upper
50.'s°F at Ukiah and Santa Rosa (See Figure 3.4-4.) During the
summer, temperatures show considerable variation ranging from the
low 60's°F at Eureka to the low 90's°F at Ukiah, Davis and
Sacramento. Maximum temperatures generally reach a peak in July
and August in all areas except along the north coast where the
maximum is generally shifted 10 August and September. -.
37
54
60
Figure 3.4-2
Mean Annual Temperature Contours (°F) in the Ukiah District
38
CD
IV
i~
(V
Q.
E
CD
90
80
70 -
60 -
50
40
D J
-i — i — i 1 1 — r
MAM J J A
Figure 3.4-3
Ukiah District
Mean Temperature
Coastal _
Coastal Mountain
Coastal Plain
Figure 3.4-4
Ukiah District
Mean Maximum Temperature
SON
Figure 3.4-5
Ukiah District
Mean Minimum Temperature
70
60 -
50 -
40 -
I 30
E
CD
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"i — i — i — i — i — i — i — i — i — i — i — r
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100
90 "
80 -
70 -
60 -
50 -
t — i — i — i — i — i — i — i — i — i — i — r
DJFMAMJ JASON
39
Mean Minimum
Figure 3.4-5 indicates that during the winter months,
minima in the mountainous and valley areas tend to be in the mid-
30's°F. Along the immediate coastline, temperatures are gen-
erally in the low to mid-40's°F. By summertime, overnight lows
in- the mountains and the Central Valley are in the mid to upper
50's°F. Along the coastline, temperatures generally remain in
the low 60's°F.
3.4.2
Temperature Extremes
Temperature extremes for key stations in each of the
three climatic zones identified for the Ukiah District are pro-
vided in Tables 3.4-2 through 3.4-4. Temperature extremes are
strongly influenced by mi crocl i mat ol ogi cal effects and consider-
able caution must be used when identifying extreme temperatures
for use at locations within the Ukiah District. Some locations
may not be adequately described by the key stations provided in
the tabl es .
The data indicate that in the Coastal CZ, record maximum
temperatures range from 83°F at Eureka to 116°F at Healdsburg.
Temperatures of this magnitude at coastal locations generally
occur in conjunction with "Santa Ana" conditions which occur most
frequently during late summer and fall, but which can occur
during any time of the year. During a Santa Ana, air is com-
pressed and heated as it rapidly descends from higher elevations
in the interior resulting in hot, dry conditions at coastal
California locations.
Record low temperatures along the Coastal CZ range from
a minimum of 16°F at Santa Rosa to 23°F at San Rafael. Record
low temperatures are generally associated with particularly large
outbreaks of Artie air which occasionally reach this area during
the winter.
In the nearby Coastal Mountain CZ , data are only pro-
vided for Ukiah. The record maximum temperature at Ukiah of
115°F occurred during September. This temperature probably
occurred during Santa Ana conditions. The wide temperature range
experienced in this zone as opposed to the Coastal CZ reflects
the increase in distance from the moderating influence of the
Pacific Ocean. The record minimum temperature at Ukiah was 13°F.
This is colder than the record minima observed at coastal sta-
tions, once again reflecting the more continental nature of the
area .
Record temperatures are available for two stations in
the Central Plain CZ as indicated in Table 3.2-4. Record maxima
range from 113°F at Davis to 115°F at Sacramento. Temperatures
of this magnitude can occur either with "Santa Ana" conditions or
during late summer when surface heating reaches a maximum at
40
low-lying inland locations. Record low temperatures in the
Central Plain CZ are 19°F at Davis and 20°F at Sacramento.
Minimum temperatures reflect local terrain and mi c rometeor o-
logical effects as well as such factors as the degree of urban
development and the length of record available for the data base.
However, the table would indicate that temperatures -lower than
20-°F represent a typical extreme minimum value at Sacramento
Val 1 ey stations.
3.4.3
Frost-Free Period
The growing season varies considerably as a function of
specific crop types. Some types of vegetation continue to grow
when air temperatures are near freezing (32 F), whereas other
forms of plant life die at temperatures above freezing. In
general, it is convenient to define the growing season for a
particular region by noting the mean number of days between the
first and last occurrence of freezing temperatures, i.e., the
frost-free period.
The mean length of the growing season is depicted by
isolines of 50 day intervals for the entire Ukiah District in
Figure 3.4-6. As indicated in the figure, the growing season
length differs considerably at coastal locations as compared to
regions located further inland. The coastal areas are largely
influenced by nearby Pacific waters. The marine environment
tends to warm ambient air masses in winter and reduce air temper-
atures during the summer months. Coastal areas in the Ukiah
District experience growing seasons on the order of 300 days
south of Eureka decreasing to around 200 days near the Oregon
border. This maritime influence is limited, however, to a very
narrow strip of land along the coast that extends roughly 10
miles inland. In areas of elevated terrain, within the Coast
Ranges, the mean growing season is reduced to less than 150 days
in portions of Lake and Mendocino Counties. In most areas of the
district, the growing season is between 200 and 300 days in
length. The mean frost-free period for the Central Plain CZ
ranges between 250-300 days, offering a rather lengthy growing
season for this key agricultural area. This area constitutes one
of the most important agricultural zones in the United States.
Table 3.4-5 presents 15 years of historical freeze data
for selected stations. For each year since 1960, the occurrence
of the last spring freeze and first fall occurrence of 32°F are
provided. The number of Julian days between the freezing events
are also listed to provide the growing season length.
In summary, little difference in frost-free period
lengths is experienced along the coast south of Eureka. Inland
stations observe a considerable change in the length of the
frost-free period. Sacramento Valley locations experience frost-
free periods ranging from 250 days in the west to 300 days along
the Sacramento River. The mountainous areas reveal a wide range
of growing season lengths with growing seasons often less than
150 days at the higher elevations.
41
15 0
2 0 0 . ELK VALLEY
AHCATA
7? W.SACRAMENTO
Figure 3.4-6
Ukiah District
Frost-Free Period or Length of Growing Season by 50-Day Intervals
42
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3.5
PRECIPITATION
Precipitation plays a very important role in the effec-
tive management of large land areas for agriculture, forest
management, energy development or other pertinent interests.
Precipitation is one of the most basic of climatolog-ical para-
meters and is best described in terms of seasonal and annual
means and extremes coupled with a discussion of the type of
precipitation experienced in a given area . A region can be prone
to either general prolonged rainfall or precipitation occurrences
in short, violent bursts, such as heavy showers or thunderstorms.
The nature of the precipitation is almost equal in importance to
the amount of precipitation in terms of the effectiveness of the
moisture for interests such as agriculture. In addition, the
type of precipitation (i.e., liquid vs. frozen) and the amount of
each also plays an important role.
Precipitation results from the expansion and cooling of
ascending air. Therefore, it is important to investigate and
understand the atmospheric conditions that cause large masses of
air to spontaneously rise. Three characteristic causes that can
result in precipitation are :
• Convective lifting due
d i t i o n s
to unstable atmospheric con-
• Orographic or terra in- induced lifting of air masses
• Large scale atmospheric disturbances
The three are not mutually exclusive, and precipitation
is generally not the result of just one type, but more often the
joint action of several types of atmospheric lifting processes.
The following sections provide a detailed breakdown of
precipitation amounts, types and frequencies. Seasonal and
annual means and extremes are provided as well as rainfall inten-
sity, and a detailed discussion on snowfall. More unusual types
of precipitation such as hail are discussed in the section pro-
vided on severe weather.
3.5.1
Annua 1 Distribution
Figure 3.5-1 presents a base map which includes the
selected stations for which precipitation data are available. A
climatic zone overlay (Overlay C) for the Ukiah District is
suitable for use with the precipitation maps.
Precipitation in California and within the Ukiah Dis-
trict is primarily the result of the influence of maritime
Pacific air and orographic influences imposed by the substantial
terrain within the region. The neighboring Pacific Ocean serves
as the major moisture source for precipitation in the district.
44
JCRESCENTM
IS
COASTAL MOUNTAIN
SACRAMENTO
SAN RAFAEL* A
Figure 3.5-1
Selected Precipitation Stations for the Ukiah District
45
Therefore, locations closest to the westward facing slopes of
higher terrain experience the heaviest precipitation totals in
the district.
The mean annual precipitation for the Ukiah District is
depicted on Figure 3.5-2 in the form of contours ( i s o try e t s ) . An
id-entical map is provided with this district report as a color
coded overlay (Overlay E) to facilitate inter-parameter compari-
sons and correlations by the reader. The figure indicates con-
siderable variation in annual rainfall totals through the Ukiah
District. Totals range in excess of 120 inches in the higher
elevations of Humboldt and Del Norte Counties to less than 15
inches in Colusa County. In Del Norte and Humboldt Counties,
rainfall amounts are generally in excess of 70 inches along the
coast and the extreme north and in excess of 50 inches in the
remainder of Humboldt County. Rainfall amounts generally
increase with inland progression, reaching a maximum on west and
southward facing slopes of elevated terrain. Maximums occur in
Del Norte County and also in the Humboldt Redwoods State Park
area of southwestern Humboldt County. In this latter location,
rainfall amounts reach in excess of 110 inches. Further to the
south in Mendocino, Sonoma and Lake County rainfall amounts are
generally between 40 to 70 inches per year in the higher eleva-
tions of the Coast Ranges reaching totals in excess of 80 inches
south of Lakeport and in portions of northwestern Mendocino
County. Rainfall amounts along the coastline of Marin, Sonoma
and Mendocino Counties range from around 40 inches in the south
to 70 inches in the north. Rainfall amounts are generally lower
in valley locations along the Russian and Santa Rosa Rivers. The
city of Santa Rosa, for example, experiences an annual precipita-
tion total of just 30 inches per year while Ukiah, further to the
north, experiences a total of about 40 inches. A marked decrease
in annual precipitation amounts is exhibited in the Central Plain
CZ which includes most of Colusa, Yolo and Solano Counties. In
these regions, rainfall amounts are generally around 15 to 20
inches per year with amounts of less than 15 inches in some
locations.
3.5.2
Seasonal Precipitation
A major portion of the precipitation that occurs in
California is associated with cyclonic storms, both surface and
upper air. Cyclonic storms originating in the western Pacific
are intensified as they move through the Gulf of Alaska. These
storms are a winter season phenomenon which result in a distinct
rainy season in California during the winter months. The amount
of precipitation associated with these storm systems depends upon
the "storm track" or path with the greatest amounts of precipi-
tation occurring near the storm center.
Rainy season storms from the west can result in rain for
prolonged periods when the storm-track becomes established across
northern California. Rains may last for a week or more with only
partial clearing between episodes. The actual amount of precipi-
46
Figure 3.5-2
Mean Annual Precipitation (Inches) in the Ukiah District
47
tat ion at a given station in the District, therefore, will be
dependent upon such factors as (1) storm path, (2) station eleva-
tion and (3) nearby terrain features. Storms from the northwest
dre the most common type of rainy season system and often bring
heavily saturated air masses which can result in considerable
flooding during the winter season.
Table 3.5-1 provides monthly precipitation means and
extremes for selected station locations throughout the Ukiah
District. A review of these statistics indicates that in each of
the climatic zones, a definite rainy season exists between late
fall and early spring. Coastal areas and the windward -slopes of
the coastal ranges experience the greatest precipitation totals.
Precipitation amounts generally increase with northward progres-
sion due to the closer proximity of the northern portion of the
region to the mean rainy season storm track. However, in
California, elevation is usually the critical variable in the
determination of precipitation amounts.
Rainy season, cyclonic storm and frontal activity
throughout the district constitutes the primary form of precipi-
tation observed in the Ukiah District.
3.5.3
Snowf a 1 1
Snowfall has been observed at many locations within the
Ukiah District. However, snow only accumulates in the higher
elevations of the Coast Ranges. Table 3.5-2 provides the his-
torical record of maximum monthly snowfall amounts for various
stations throughout the Ukiah District. Average amounts are not
provided as snow is extremely rare at sea level and low-lying
stations. Snow is not an important climatic parameter at such
locations and is more of a novelty topic.
Table 3.5-3 provides the mean monthly and mean annual
maximum snowpack depth and associated water content for stations
within the mountainous areas of the Ukiah District. Figure 3.5-3
illustrates the North Coastal Snow Basin (#2) located in the
Ukiah District as organized by the California Department of Water
Resources, Division of Flood Management. Snow basins are deter-
mined according to particular river systems in which snow melt
can contribute a significant water supply.
The greatest snowfall on record for the entire snow
season in California fell in 1906 and 1907 at Pomerac in Alpine
County where 884 inches of snow was recorded at 8000 feet MSL.
The average seasonal snowfall at that station is 450 inches. The
greatest 24-hour snowfall occurred at Giant Forest in Sequoia
National Park at 6360 feet MSL on January 19, 1933 when 60 inches
fell. It should be noted that there are relatively few snow
observation stations in the Sierra, therefore, snowfall amounts
in excess of these record amounts may have occurred.
48
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51
• TATt OF CALIFORNIA
THE RESOURCES AGENCY OF CALIFORNIA
DEPARTMENT OF WATER RESOURCES
DIVISION OF FLOOD MANAGEMENT _
CALIFORNIA COOPERATIVE SNOW SURVEYS
INDEX TO BASIN MAPS
1978
COLORADO
DESERT
Figure 3.5-3
Snow Basin Map
52
In the Ukiah District, at non-mountain stations, the
maximum monthly snowfall occurred at Santa Rosa with an accumu-
lation of 6.5 inches. At Ukiah, in Mendocino County, 5 inches of
snow have occurred in January. Other monthly maximum snowfall
data are presented in Table 3.5-2.
3.5.4
Precipitation Frequency
An analysis of rainfall intensity for selected areas
offers added insight into regional precipitation characteristics.
Rainfall frequency and intensity studies, sometimes referred to
as pluvial indices, provide an understanding of the nature of
precipitation and rainfall in a given region. Isopluvial maps
facilitate an evaluation of rainfall intensity for particular
areas over selected short-term time periods or intervals. Isoh-
yet analyses coupled with isopluvial studies provide an indica-
tion of the nature of the precipitation means for the area , i.e.,
frequent light rains versus sporadic heavy rainstorms.
Appendix A provides isopluvial analyses for the Ukiah
District as well as for the entire state of California. These
figures provide information for the following return periods and
rainfall duration times:
2 year-6 hour precipitation
5 year-6 hour precipitation
10 year-6 hour precipitation
25 year-6 hour precipitation
50 year-6 hour precipitation
100 year-6 hour precipitation
2 year-24 hour precipitation
5 year-24 hour precipitation
10 year-24 hour precipitation
25 year-24 hour precipitation
50 year-24 hour precipitation
100 year-24 hour precipitation
These maps present precipitation amounts received within
designated time periods based on recurrence intervals of 2, 5,
10, 25, 50 or 100 years. For example, Figure A - 1 provides iso-
pluvials of precipitation amounts for a 6 hour period, experi-
enced at least once in a 2 year time frame. The isoline inter-
vals provided on these maps were designed to provide a reasonably
complete description of isopluvial patterns in various regions of
the state. Dashed intermediate lines are placed between the
normal isopluvial intervals where a linear interpolation would
lead to erroneous results.
Rainfall frequency values for selected key stations
within the Ukiah District were obtained from the Appendix and
summarized in Table 3.5-4. This table provides easy reference to
pluvial indices for the climatic zones throughout the district.
The tables and figures indicate that coastal and coastal mountain
areas could expect the most intense rainfall amounts over a 6 or
53
Table 3.5-4
Pluvial Indices (in tenths of inches)
at Selected Stations in the Ukiah District
Time Frame
6 HOUR
24
HOUR
Return Period
2 YR
10
YR 25 YR 50 YR
2 YR
10 YR
25 YR
50 YR
Station
Coastal
Crescent City
22
30
34 36
45
65
80
80
Orick
20
27
30 33
45
68
75
85
Eureka
16.5
23
28 31
30
45
52
56
Bridgeville
20
26
30 32.5
47
65
75
80
Garbervil le
22
26
32 35
50
70
80
88
Ft. Bragg
17
21
25 29
34
45
50
55
Annapolis
27
36
40 43
60
80
95
95
Santa Rosa
18
23
26 27.5
34
45
50
60
Vallejo
14
19
21 22.5
X
25
33
45
45
Coastal Mountain
Ukiah
18
23
26 27.5
35
50
62
68
Cloverdale
24
30
38 38
50
72
79
90
Lakeport
14
18
20 22.5
30
44
52.5
60
Coastal Plain
Williams
12
16
17 19
20
27.5
32.5
36
Woodland
12
16
18.5 20
20
28
33
38
Dixon
14
20
24 27
24
35
42
45
Vacaville
16.5
22
27 29
32
47
55
62
54
24 hour period. At Annapolis, for example, rainfall could total
as high as 6 to 10 inches in a single 2 4 hour period. At coastal
and coastal mountain locations, 24-hour maxima are quite variable
ranging between 4 and 8 inches slong the north coast and between
3 and 5 inches along the south coast. In the Sacramento Valley,
maximum 24-hour values are generally betweed 2 and 4 inches. The
isopluvial maps, as previously mentioned, strongly reflect the
influence of topography on the nature of precipitation as evi-
denced by the values indicated in Table 3.5-4 for the District's
mount a i nous areas .
55
3 . 5
PREVAILING WINDS
Wind is considered a primary climatic parameter since
air flow characteristics directly affect ambient air moisture
content and regional temperature levels. Seasonal and diurnal
air flow patterns can promote periods of wet or dry weather as
we-11 as determine hot or cold climates. The prevailing winds are
responsible for much of the climatic characteristics of an area
and are deeply interrelated with other climatic parameters. The
distribution of wind direction and wind speed are used to cate-
gorize this parameter.
Observations of wind direction
into the 16 cardinal compass directions
tional abbreviation or the heading in
associated with each compass heading are
Meteorological
associated with
which the air is flowing. In other words, north or
winds mean that air is moving from north to south.
are usually classified
using either a direc-
degrees. The degrees
listed in Table 3.6-1.
convention requires that the compass heading
a given wind observation is the direction from
norther! y
The following sections will describe wind on both an
annual and seasonal basis. A primary tool used to graphically
describe the prevailing wind conditions at a given station is
known as a wind rose. As described in detail in Section 4.2.1, a
wind rose is a plot of the frequency of winds from each of the
sixteen cardinal directions. The diagram resembles a compass
face with the length of the line drawn for each direction indi-
cating the frequency of occurrence of flow from that direction
for the indicated period of record.
3.6.1
Annual Wind Distribution
California lies within the zone of prevailing westerly
winds and is situated on the east side of the Eastern Pacific
semi-permanent high pressure center. Since general air flow
patterns in the Northern Hemisphere are clockwise ( a nt i cy c 1 oni c )
about high pressure centers, basic air flow over California is
from the west and northwest. Figure 3.6-1 illustrates a typical
pressure situation off the California coast and depicts the
associated wind flow patterns. As the seasons progress, there
exists considerable variation in this generalized scheme due to
mesoscale (several hundred miles) and synoptic (thousands of
miles) scale pressure distribution changes. Most importantly,
several mountain chains within the state are responsible for
deflecting the large scale flow. Except along the immediate
coast, wind direction and speed is likely to be largely a func-
tion of local terrain and orographic effects rather than the
prevailing circulation patterns observed in a hemispheric sense.
Figure 3.6-2 depicts various selected station locations
in the Ukiah District for which reduced historical wind speed and
direction data have been summarized. Annual wind roses are
superimposed on this study map for selected key stations within
56
Table 3.6-1
Wind Direction Classification
Direction
(Abbreviation)
Di recti on
( Degrees )
Di recti on
(Winds From)
N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
sw
wsw
w
WNW
NW
NNW
348.75 - 11.25
11.25 - 33.75
33.75 - 56.25
56.25 - 78.75
78.75 - 101.25
101.25 - 123.75
123.75 - 146.25
146.25 - 168.75
168.75 - 191.25
191.25 - 213.75
213.75 - 236.25
236.25 - 258.75
258.75 - 281.25
281.25 - 303.75
303.75 - 326.25
326.25 - 348.75
North
North - Northeast
Northeast
East - Northeast
East
East - Southeast
Southeast
South - Southeast
South
South - Southwest
Southwest
West - Southwest
West
West - Northwest
Northwest
North - Northwest
<
57
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58
20
l_
20
40
_J_
MILES
• WILLITS
\
i
• CALPELLA
PT ARENA . .
• UPPERLAKE *^\ V
• LAKEPORT \ \ 1
\ • KELSEYVILLE . __ _ — L
v"^. i • DUNNIGAN
A
• CLOVEROALE
HEALDSBURG
K
60
-I
*ANTA,l~ k
^ f\\» SONOMA s« VACAVILLE
ROSA
\ DAVIS •
t WOODLAND
W.SACRAMENTO
FAIRFIELD
Note
RIO VISTA
SAN RAFAEL
KENTFIELD
Figure 3.6-2
Annual Wind Roses at Selected Key Stations
in the Ukiah District
Each Division on the Roses is Equal to an Annual Frequency of 5%.
59
each climatic zone in the district coupled with trajectory analy-
ses based upon the use of the most frequently occurring wind
direction at each station. The climatic zone overlay (Overlay C)
map may be used to isolate these particular areas. A detailed
analysis and breakdown of wind speed versus wind direction char-
acteristics is provided in the dispersion meteorology section.
The annual wind roses provided in Figure 3.6-2 indicate
that the flow along the coast is from the northwest and north at
all stations with the exception of Crescent City where south-
easterly flow represents the prevailing wind. However, even at
this station, a strong secondary maximum for winds from the
nort h- northwest exists. At coastal mountain stations, flow tends
to be up the major river valleys including the Santa Rosa,
Russian and Napa River Valleys. This results in a prevailing
south to southeasterly flow at stations such as Ukiah, Santa
Rosa and Napa. Further inland, in the Sacramento Valley, flow is
once again upvalley as evidenced by southerly flow at Sacramento,
southeasterly flow at Williams. The flow in the Sacramento
Valley and in the Coastal Mountains is still maritime in nature
coming into the region through the gap in the Coast Ranges in the
San Francisco - Oakland area.
Figure 3.6-3 provides an annual trajectory analysis
based upon the most frequently occuring wind direction at each of
the stations for which wind data were available in the Ukiah
District. The prevailing downcoast flow at coastal stations from
the northwest to north is evident as is upvalley flow in most of
parts of Sonoma, Mendocino, Lake, Napa, Solano, Yolo and Colusa
Counties. The area contains considerable rugged terrain and the
wind flow as presented in Figure 3.6-3 may not be indicative of
sites which are dominated by local terrain affects.
3.6.2
Seasonal Wind Distribution
Seasonal wind data are available in the Ukiah District
for Eureka, Areata, San Rafael, Ukiah, Fairfield (Travis AFB) and
Sacramento and are presented in Table 3.6-2. The first three
stations are indicative of conditions along the Pacific Coast.
Ukiah is indicative of conditions in the Coast Ranges while Fair-
field and Sacramento are indicative of sites in the Sacramento
Valley. At Eureka and Areata in Humboldt County, downcoast north
to northwesterly flow prevails during the period spring through
fall. During this time of the year, California is under the
influence of the semi-permanent Pacific high pressure zone which
results in an onshore maritime flow at most California coastal
locations. The sea breeze regime which results from this pres-
sure pattern generally brings an ample supply of moist maritime
air to coastal locations resulting in a distinctly maritime
climate with modest temperature ranges. Both Eureka and Areata
show deviations from this trend towards onshore flow during the
winter months with southeasterly flow at Eureka and easterly flow
at Areata. During the winter months, drainage flow from inland
60
ELEVATIONS
6000
3000
1500
500
0
»
CRAMENTO
Figure 3.6-3
Trajectory Analyses for the Ukiah District
61
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62
areas of substantial terrain tends to dominate the annual distri-
bution. This offshore component is further supplemented by
southeasterly and easterly flow in advance of migratory pressure
systems during the rainy season months.
Further down the coast at San Rafael, the prevailing
distribution is somewhat more erratic. Northwesterly flow dom-
inates during most months but is absent during midwinter as well
as during late summer and early fall. Once again, the north-
westerly flow is indicative of the maritime sea breeze regime
while southeasterly and easterly flow at San Rafael represents a
combination of upvalley flow as well as outflow from the Central
Valley of California.
Ukiah is representative of conditions at an inland
valley location. Here, the trend is similar to that observed at
San Rafael. South-southeasterly flow prevails during the winter
months and during late summer while north and northwesterly flow
dominates during other periods of the year . The northwesterly
flow is indicative of the general down coastal flow observed in
Northern California particularly during the summer months. The
switch to south-southeasterly flow again occurs in late summer as
surface heating becomes most intense and topographical influences
dominate. This results in upvalley flow as warm air masses tend
to move upslope. During the winter months, the south-southeast-
erly flow reflects the heavy influence of migratory storm systems
which result in southerly and southeasterly flow on many occa-
sions, particularly in Northern California.
Finally, Fairfield and Sacramento provide data indica-
tive of conditions in the Sacramento Valley portion of the Ukiah
District. Southwesterly flow dominates at Fairfield as maritime
air moves inland through the Carquinez Straits. At Sacramento,
southwesterly flow dominates during the summer as maritime air
comes in through the Carquinez Straits and upvalley into the
Sacramento Valley. During winter, southeasterly and south-south-
easterly flow is evident as noted at most stations within the
District.
At coastal and coastal mountain stations, wind speeds
tend to be strongest during the period April through June. Down
coastal flow is well established during this period resulting in
brisk winds ranging from 5 knots at Ukiah to over 8 knots at
Eureka and Areata during April. Wind speeds tend to be lowest at
these locations during the fall months. At Fairfield and Sacra-
mento in the Sacramento Valley, wind speeds are clearly strongest
during summer when the maritime influence of the sea breeze is
strongest as air rushes through the San Francisco-Oakland area
moving southward into the San Joachin Valley and northward into
the Sacramento Valley. Wind speeds tend to be lowest in this
area, once again, during the fall months.
63
3.7
EVAPORATION AND RELATED PARAMETERS
Evaporation is the physical process by which water is
transformed from the liquid to the gaseous state. The rate of
evaporation in a particular region is dependent upon many cli-
matic parameters, but is primarily influenced by wind, temper-
at-ure, relative humidity, sky conditions, precipitation and solar
radi at i on .
E vapot ransp i rat i on is the process whereby water vapor is
returned to the atmosphere both by living plants (transpiration)
and from the earth's surface (evaporation)-. An assessment of
regional evapotranspiration is important to the water and agri-
cultural industries as it provides a complete picture of natural
water demand for a given geographical area.
Solar radiation is the earth's principle source of en-
ergy. This energy is naturally dispersed in numerous forms such
that much of the received solar energy is used to generate winds,
heat air masses, as well as supply latent heat energy to the
atmosphere by contributing to the rate of evaporation of large
quantities of water into the atmosphere. Consequently, mean
monthly and annual solar radiation levels for particular loca-
tions are often expressed in terms of equivalent evaporation
units. The standard conversion of solar radiation units, as
expressed in Langleys, to inches of evaporation, requires that 1
inch of evaporation be equivalent to 1486 Langleys.
3.7.1
Evaporation and Evapotranspiration
The California State Department of Water Resources has
determined regional evaporative demand areas on the basis of
similar monthly levels of evaporation and evapotranspiration
rates. These areas are provided in Figure 3.7-1 for the entire
state of California.
The Ukiah District includes three of the eleven state-
wide zones of similar evaporative demand. A contour map depict-
ing areas of equal annual evaporative demand levels for the Ukiah
District is provided as Figure 3.7-2. Note that a considerable
gradient of evaporative demand exists. These rapid changes in
regional evaporation rate are a result of the considerable dif-
ference between the nearby Pacific Ocean and the Sacramento
Valley. Air masses along the coast experience modest temperature
variations coupled with high relative humidity. These factors
significantly limit the potential rate of evaporation since the
ambient air has a diminished ability to hold additional water
vapor. This is diammetrically opposed to the evaporative poten-
tial of the dry valley areas further east.
A comparison of annually averaged evaporative demand and
evapotranspiration rates for different geographical areas can
lead to ambiguous results. Annual evaporative totals for two
areas may be similar, but monthly patterns of evaporation and
64
c r i c
ZONES OF SIMILAR EVAPORATIVE
DEMAND IN CALIFORNIA
1. North Coast, Coastal Valleys and Plains
2. North Coast Interior Valleys
3. Northeastern Mountain Valleys
4. Sacramento Valley Floor
5. San Joaquin Valley Floor
6. Central Coast Interior Valleys
7. Sierra
8. Central Coast, Coastal Volleys and Plains
9. South Coast, Coastal Valleys and Plains
10. South Coast Interior Valleys
11. Southern California Desert *
\
t *■ -■ • <■
\
V
L- )
"~\
Figure 3.7-1
Source: "Vegetative Water Use in California, 1974", State of
California Department of Water Resources
65
35
ELK VALLEY
W SACRAMENTO
Figure 3.7-2
Annual Evaporative Demand
in the Ukiah District
Estimated from evaporation observed in non-irrigated environments adjusted to
appropriate evaporation from Class "A" pans in irrigated pasture environments.
66
evapotransiration may differ significantly. Monthly tabulations
of average pan evaporation rates and estimated potential evapo-
transpiration rates for the various California climatic regions
are presented in Table 3.7-1.
Maximum evaporation rates generally occur during July.
During this month, in all climatic regions, the incidence of
solar radiation is at a maximum. The North Coast Coastal Valleys
and Plains experience about 4.5 inches of evaporation during July
while the North Coast Interior Valleys experience just over 9
inches of evaporation during this month. In the Sacramento
Valley, average pan evaporation rates reach just over 10 inches
during the month of July. In winter, evaporation rates drop to
less than an inch in the North Coast Coastal Valleys and Plains
and between one and two inches in the North Coast Interior Val-
leys and Sacramento Valley. Figure 3.7-2 indicates that annual
average pan evaporation rates are greater than 65 inches in Yolo
County and less than 35 inches in the extreme northwest.
The ratio of ev a pot ra ns p i rat i on to evaporation (ET/Ep)
is obtained empirically by simply observing and comparing simul-
taneous pan evaporation and net water loss from vegetation soil
tanks (the tank is designed such that all water added to the
apparatus and all water left after a testing period can be mea-
sured). This ratio thus allows a more definitive evaluation of
water demand in a particular region.
Since evapot ransp i rat i on values are so dependent upon
crop and vegetation type, it is useful to observe ET/Ep ratios on
a monthly basis for the entire growing season of particular
crops. In general, potential evapotranspiration values as pre-
sented in Table 3.7-1 are determined by using grass as the stan-
dard vegetation type. Table 3.7-2 provides a summary of observed
monthly ET/Ep ratios for the principle irragated crops in Cali-
fornia as provided by the California State Water Resources Con-
trol Board in Sacramento.
3.7.2
Sky Conditions
Sky cover is a measure of the degree of cloudiness
characteristic of a given area for a certain time period. Sky
cover conditions experienced in a particular region are inter-
related with the mean incoming solar radiation, mean temperature,
and precipitation levels, as well as having numerous secondary
effects on many other climatic parameters, all of which effect
the local evaporative demand. In addition, as discussed in
Section 4.2-2, sky cover has an application to dispersion meteor-
ology through its impact on insolation, and thus is an important
parameter in the determination of atmospheric stability.
Clouds substantially insulate the surface from receiving
large quantities of solar energy. Reflection and scattering of
light energy from cloud tops and cloud interiors contribute
significantly to the overall reduction of light received at
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71
ground level. Generally, cloud cover is classified according to
various categories. These categories include clear or cloudless
sky conditions, mostly clear skies, partly cloudy conditions,
mostly cloudy and cloudy conditions, or completely overcast
skies. In order to make sky cover observations more definitive,
these observations are defined in terms of categories using
fractional units expressed in tenths of the sky covered by clouds
(See Table 3.7-3).
Table 3.7-3
Sky Cover Categories
Generalized Category
clear
mostly clear
parti y cl oudy
most! y cl oudy
cloudy or complete overcast
Sky Cover in Tenths
0
0-3
4-7
8-10
10
Mean monthly and annual sky conditions at coastal and
valley stations are provided in Figures 3.7-3 and 3.7-4. At
Eureka, very little variation is evident as a function of the
season of the year. The mean sky cover ranges from 6/10ths to
8/10ths with a maximum occurring during December and a minimum
occurring during September. During all other months of the year ,
sky cover totals 7/10ths at Eureka. This station is heavily
influenced by the maritime influx of air from the Pacific Ocean.
Onshore flow dominates during all months of the year and fog and
low stratus are quite common. The maximum for cloud cover during
the winter represents the increased frequency of migratory low
pressure systems during this month while the minimum in September
reflects the generally good weather experienced throughout Cali-
fornia during fall due to the presence of the sem i - perma nent
eastern Pacific high pressure system.
Further down the coast at San Rafael, considerable
variability is evident in the sky cover data ranging from l/10th
during August and September to a maximum of 6/10ths during Decem-
ber and January. The low frequency of cloudiness during the
summer months is once again indicative of the improved sky cover
conditions experienced at most California coastal stations during
late summer. The high frequency of cloudiness during winter
reflects the increased frequency of storm systems passing through
the area. In addition, cloud cover remains fairly high through
May, representing the influence of maritime air in this region
during the spring months and the fairly high frequency of occur-
rence of low cloudiness and fog.
At Sacramento in the central plain climatic zone, condi-
tions are similar to those experienced at San Rafael. Cloudiness
reaches a peak in mid-winter with a minimum during late summer
and early fall. The winter maximum reflects both the increased
frequency of the passage of migratory storm systems as well as
72
u
MEAN SKY COVER - EUREKA
9
8
8
(33 YEARS OF DATA)
(IN TENTHS)
7
m
7 7 7 7 7 7 7 7 7 7
6
-
6
5
4
3
2
1
Annual
Mean
6.9
M
MONTH
10
9
8
7
6
5
4
MEAN SKY COVER - SAN RAFAEL (TRAVIS AFB)
(4 YEARS OF DATA)
(IN TENTHS)
2 2
1
1
Annual
Mean
3.7
M
A
M
MONTH
J
A
Figure 3.7-3
Coastal Climatic Zone
Monthly and Annual Sky Cover Distribution
73
10
MEAN SKY COVER - SACRAMENTO AIRPORT
9
(27 YEARS OF DATA)
(IN TENTHS)
8
en
LU
>
o
o
7
6
5
7
7
6 6 6
>-
o
5
oo
4
3
4
1—
3
2
2
2
1
1
1
ANNUAL
MEAN
4.1
FMAMJJAS
MONTH
Figure 3.7-4
Central Plain Climatic Zone
Monthly & Annual Sky Cover Distribution
74
heavy stratus and fog which tends to occur over this region
during the winter. The frequency of low stratus and fog remains
fairly high through the spring months. During late summer,
surface heating reaches a maximum and the skies tend to be fairly
cloudless throughout the San Joaquin and Sacramento Valleys. Sky
cover generally averages between 1/1 Oth and 2/10ths at -Sacramento
in- the summer and early fall months.
Table 3.7-4 provides the diurnal, monthly and seasonal
frequency of mostly clear, partly cloudy and mostly cloudy condi-
tions at Areata and Ukiah. These data are only available for
stations for which summarized digital data in the form of STAR
summaries are available. At Areata, located on the north coast
in Humboldt County, cloudy conditions clearly dominate reaching a
maximum in the early morning hours. The frequency of clear
conditions reaches a maximum during the late afternoon and early
evening hours. At Ukiah, mostly clear conditions dominate at
this inland valley location. Clear conditions reach a maximum
during the middle of the night while cloudy conditions are most
frequently observed during the early morning hours. Partly
cloudy conditions are most frequent during the afternoon and
early evening hours as fair weather cumulus develop during the
period of most intense surface heating.
The importance of sky cover as a parameter affecting
atmospheric stability will be discussed further in Section 4.2.3
and is especially detailed in Table 4.2-4
3.7.3
Solar Radiation
Monthly-annual averages of total incoming solar radia-
tion for the various evaporative demand zones in California
(equivalent in inches of evaporation of water) are presented in
Table 3.7-5. The Ukiah District includes areas in the North
Coast, Coastal Valleys and Plains, North Coast Interior Valleys
and Sacramento Valley.
The Ukiah District, on an annual basis, receives an
abundant amount of sunshine, particularly in the Sacramento
Valley. The north coastal portion of the Ukiah District receives
approximately 50% of the total possible sunshine on an annual
basis. In the Sacramento Valley, over 70% of the total possible
hours of sunshine are received annually.
A further distinction can be made between the various
climatic zones in the Ukiah District when comparing solar radia-
tion data on a monthly basis. Table 3.7-6 provides a monthly-
annual breakdown of mean daily solar radiation in Langleys as
observed at selected stations within the Ukiah District. As
indicated by this table, the Coastal Mountains receive abundant
amounts of sunshine during the year. Daily solar radiation
totals reach over 700 langleys at Upperlake in June and July.
Along the coast and in the Sacramento Valley, values exceed 600
langleys during the period May through August. During winter,
daily totals drop off to less than 200 langleys along the coast
at some stations.
75
Table 3.7-4
Seasonal and Diurnal Frequencies (%)
of Sky Coverage Conditions in the Ukiah District
Time
Areata
Ukiah
0-3
4-7
8-10
0-3
4-7
8-10
01
29.0
7.3
63.6
66.5
7.7
25.8
02
*
*
•
64.0
8.2
27.8
03
*
•
*
62.9
8.7
28.4
04
26.7
7.6
65.7
61.8
8.3
29.9
05
*
•
*
60.8
7.9
31.3
06
•
•
•
57.6
8.6
33.8
07
21.7
8.4
69.9
54.1
9.1
36.8
08
*
•
•
51.5
10.4
38.1
09
*
*
•
51.0
9.4
39.6
10
23.4
11.0
65.6
51.7
9.5
38.7
11
*
•
•
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10.2
35.6
12
•
•
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55.7
10.7
33.6
13
30.7
12.1
57.2
55.9
11.4
32.7
14
*
*
•
56.5
11.4
32.1
15
•
•
•
56.2
12.1
31.7
16
31.8
13.8
54.4
56.4
11.2
32.4
17
*
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11.3
32.4
18
*
•
•
55.3
13.3
31.4
19
32.2
11.4
56.4
58.0
12.1
30.0
20
•
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*
60.4
12.8
26.8
21
•
*
*
63.2
11.3
25.5
22
32.7
9.3
58.1
64.9
10.1
25.0
23
•
•
•
65.7
9.5
24.8
24
•
*
*
66.3
8.4
25.3
Month(s)
DEC
22.3
10.8
66.9
38.0
13.0
49.0
JAN
26.4
9.6
64.0
35.9
11.5
52.6
FEB
16.0
10.3
73.8
39.6
9.9
50.5
WINTER
21.8
10.2
68.0
37.8
11.5
50.7
MAR
29.7
11.0
59.3
42.0
13.2
44.8
APR
33.6
12.3
54.1
49.8
14.3
36.0
MAY
24.0
12.1
63.9
55.7
11.6
32.7
SPRING
29.0
11.8
59.1
49.2
13.0
37.8
JUN
24.4
8.5
67.1
73.7
9.9
16.5
JUL
26.3
6.4
67.3
89.3
4.8
5.8
AUG
32.4
8.4
59.2
87.0
5.7
7.3
SUMMER
27.7
7.7
64.5
83.4
6.8
9.8
SEP
44.3
8.1
47.6
81.4
7.0
11.6
OCT
36.0
11.4
52.6
62.7
10.1
27.2
NOV
26.2
12.6
61.3
47.4
10.8
41.8
FALL
35.5
10.7
53.8
63.8
9.3
26.9
76
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78
3.8
OTHER CLIMATIC PARAMETERS
This section presents analyses of various secondary
climatic parameters. These parameters have considerable poten-
tial for short-term influence on BLM land use alternatives, but
when considered on a long-term cl i mat ol og i ca 1 basis,- they are
le-ss significant in characterizing the climate than the para-
meters previously discussed. The particular climatic parameters
reviewed in this section include:
Dew Point and Relative Humidity
Severe Weather
Barometric Pressure
Fog and Visibility
Ocean Surface Temperatures
Variations of these particular climatic parameters are
briefly discussed and variations within specific climatic zones
of the Ukiah District are presented in the form of figures and
tables. A complete bibliography is provided in the back as for
previous sect ions.
3.8.1
Relative Humidity and Dew Point
Relative humidity and dew point temperature are dis-
cussed together in this section as they both represent measures
of the available moisture in the atmosphere as a function of
ambient air temperatures. Relative humidity describes the satur-
ation moisture percentage of the atmosphere. More accurately,
this parameter is defined by the ratio of the actual vapor pres-
sure of air to the saturation vapor pressure of ambient air
parcels. Dew point temperature represents the temperature to
which a given parcel of air must be cooled, at constant pressure
and water vapor content, in order for saturation to occur. For
example, the dew point temperature is the temperature at which
moisture condenses on grass and other exposed surfaces during the
cool early morning hours. When this temperature is below freez-
ing, it becomes the frost point temperature, i.e., the point at
which frost will develop on exposed surfaces.
Dew point and relative humidity both provide a measure
of the amount of moisture available in the atmosphere for con-
densation. However, care must be used in interpreting these
parameters. For example, the higher the relative humidity, the
higher the amount of moisture available for condensation. How-
ever, a low dew point does not necessarily mean low availability
of. moisture. The key criterion in interpreting dew point data is
the difference between the dew point temperature and the ambient
air temperature which is commonly known as the dew point depres-
sion. When this temperature difference is small, the amount of
available moisture is high. When there is no difference, the
atmosphere is saturated. Finally, when the dew poi nt ■. depress i on
is large, the amount of available moisture in the atmosphere is
79
quite small. In a great majority of normal atmospheric condi-
tions, supersaturat i on does not occur; therefore, the dew point
temperature should never be higher than the ambient air temper-
ature.
Atmospheric moisture content also plays an important
roje in air quality. High moisture levels not only reduce
visibility but can also enhance the formation of secondary air
pollutants such as sulfates and nitrates, which can further
reduce visibility.
Summary tables and figures have been provided for the
Ukiah District which present relative humidity and dew point
temperature data on a diurnal, monthly, seasonal and annual
basis. Relative humidity and dew point temperature data are
generally available only for major first order stations; however,
the data base for the Ukiah District is sufficient to provide
regional long-term averages.
Figure 3.8-1 summarizes seasonal mean dew point tempera-
ture and relative humidity for the state of California. The data
indicate that atmospheric moisture content is highest along the
coastline, particularly in the extreme northwestern portion of
the state. There is a tendency for moisture to flow in through
the Bay Area and during the late fall, winter and early spring
seasons, this moisture reaches the Central Valley. During other
seasons of the year, most of the valley is significantly dryer
than coastal locations as indicated by the figure. The southeast
desert is the dryest portion of the state during all seasons.
In the Ukiah District, relative humidities tend to be
highest in winter and lowest in summer. Detailed information on
relative humidity is presented in Figures 3.8-2 - 3.8.4. Figure
3.8-5 provides a review of average dew point temperatures on a
monthly basis at key first order stations. Finally, diurnal
distributions of relative humidity and dew point at key stations
are provided on a seasonal basis in Tables 3.8-1 and 3.8-2.
To summarize the data in the tables and figures, rela-
tive humidities remain fairly constant at a rather high level at
the coastal locations throughout the year and are consistently
lower in the Sacramento Valley. There is a strong moisture
gradient between coastal and inland stations particularly during
the warmer months.
3.8.2
Severe Weather
This section presents a basic summary of severe weather
in the Ukiah District. The regional formation and statistical
incidence of thunderstorms, tornadoes, hail and ice are discussed
in this section. The damaging effects of these abnormal weather
features are also reviewed. In comparison with other areas of
the country, thunderstorms, tornadoes, hail and ice occur rela-
tively infrequently in most portions of the state.
80
MEAN DEW POINT TEMPERATURE
Winter
Spring Summer Fall
_3 0*
60
MEAN RELATIVE HUMIDITY
Figure 3.8-1
Mean Seasonal Dew Point (°F)
and Relative Humidity {%) in California
81
90 -
80 -
70
Areata
San Rafael
>> 60
>
S 50 -I
QJ
en
40 -
30 -
20
i — i — r
i — r
0 N
A M
J
A
Month
Figure 3.8-2
Coastal Climatic Zone Monthly-Annual Humidity
Distribution in the Ukiah District
82
90 -
80
70 -
>, 60
■♦->
-5
■i—
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50 -
40 -
30 -
20
Month
Figure 3.8-3
Coastal Mountain Climatic Zone Monthly-Annual Humidity
Distribution in the Ukiah District
83
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80 -
70 -
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40 -
30 -
20
D J F M
A M J J
Month
0 N
Figure 3.8-4
Central Plain Climatic Zone Monthly-Annual Humidity
Distribution in the Ukiah District
84
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65 -
60 -
55 -
50 -
z: 45 -
■5 40 H
o
2
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30 -
25 -
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15
Areata
/
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/ Ukiah
N
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Month
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Figure 3.8-5
Ukiah District
Monthly-Annual Dew Point Temperature
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87
Thunderstorms
Thunderstorms are rare along the coast and have no well
defined season. On the other hand, thunderstorms developing over
the interior mountains are severe on occasion and occur primarily
during summer. Most of the thunderstorms that occur in the Ukiah
Di "strict cause little, if any, damage. The storms usually are
accompanied by brief gusts of wind, heavy rain and lightning as
well as some small hail. Large hail, strong winds and a funnel
cloud or tornado are quite rare. Flash flooding comprises the
primary source of damage associated with summer thunderstorms.
Winter thunderstorms generally occur in conjunction with
rapidly moving cold fronts that pass over the district. Advanc-
ing frontal systems can promote considerable instability aloft
which contributes to thunderstorm development. Summer thunder-
storms develop over mountainous and desert areas as strong sur-
face heating effects couple with moist maritime air and, in the
mountians, forced orographic lifting.
Isolines of the annual mean number of thunderstorm days
are depicted on a national scale in Figure 3.8-6. Generally, the
Ukiah District experiences 5-10 thunderstorm days per year.
Considerable data resolution is lacking on Figure 3.8-6 and the
distribution does not reflect the higher incidence of thunder-
storm days that can be experienced in the mountainous areas.
Isolated thunderstorm activity, as observed on radar over moun-
tain areas, averages as high as 50 to 60 days per year at some
locations. Lightning strikes resulting from these thunderstorms
can cause dry brush to ignite and promote forest fires. Detailed
data for selected stations in the Ukiah District are presented in
Table 3.8-3.
Table 3.8-3
Mean Number of Thunderstorm Days
Station
Areata
Eureka
San Francisco
Ukiah
Sacramento
w
int
er
2.
0
3.
0
0.
8
2.
0
0.
5
Spring
4.0
0.8
0.8
5.0
2.3
Summer
2.0
0.8
0.8
17.0
0.8
Fal 1
1.0
1. 5
0.8
6.0
1.5
Annual
4.0
6. 1
3.2
30.0
5.1
Tornadoes
Tornadoes and funnel clouds are associated with severe
thunderstorms. They develop when just the right conditions of
moisture, atmospheric stability, and winds are present. Torna-
does frequently form within thunderstorms that have organized
into lines. Frequently, but not always, these "squall lines" are
88
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89
associated with vigorous and rapidly advancing cold fronts that
promote rapid lifting of ambient air to heights in excess of
60,000 feet.
The environmental setting in California limits the
potential for the development of tornadic conditions. The near
proximity of the cool waters of the Pacific Ocean and the Eastern
Pacific semi -permanent high pressure center tends to inhibit the
necessary rapid lifting of surface air. The downward air motion
associated with this high pressure area tends to warm and stabi-
lize the atmosphere, thus creating conditions adverse to tornado
or severe thunderstorm activity. On rare occasions, surges of
cold air at upper levels move into California and can combine
with warm moist onshore surface winds to produce the unstable
atmospheric conditions necessary for tornado formation.
average
Tornadoes have been reported
frequency of only 1 or 2 per
in California, but with an
year. They are generally
not severe, in many cases causing little more than damage to
trees or light buildings. Pilots occasionally report sightings
of funnel clouds aloft, particularly off the southern California
coast. The map on Figure 3.8-7 depicts areas of tornado activity
in California for the period from 1930-1974. Table 3.8-4 pro-
vides a complete listing of historical tornado and funnel cloud
observations for the Ukiah District and nearby regions.
Fujita has presented a classification scheme for tor-
nadoes, presented in Table 3.8-5, which has been used to cate-
gorize California tornadoes as shown in Table 3.8-5. A scale is
presented below as devised by Fujita and as outlined in a report
submitted to the University of California by Meteorology Re-
search, Inc ( MR I ) . Specifications of damage are presented as
visual guidelines, and not as absolute criteria.
Table 3.8-4
Review of Tornado Sightings in the Ukiah District
Date
April 19, 1967
April 27, 1970
January 12, 1971
August 25, 1973
Time
1108
1720
1655
Location
Fairfield
Williams, Colusa
Santa Rosa
Point Arena
Type
FC*
FC
FC
FC
Remark s
Ver i f i ed by
Sacramento Radar
Funnel Cloud
90
SAN FRANCISCO
Figure 3.8-7
Tornado Activity in California
During the Period 1930-1974
91
(FO)
(Fl)
(F2)
(F3)
(F4)
(F5)
Table 3.8-5
Fujita Tornado Classification Scheme
GALE TORNADO, Light Damage
40-72 mph
Some damage to chimneys and TV antennae;
twigs off trees; pushes trees over.
break s
(F6)
(F7)
(F8)
(F9)
(F10)
(Fll)
(F12)
WEAK TORNADO, Moderate Damage
73-112 mph
Peels surface off roofs; windows broken; light
trailer houses overturned; some trees uprooted or
snapped; automobiles pushed off the road.
STRONG TORNADO, Considerable Damage
113-157 mph
Roofs torn off frame houses leaving only strong
walls upright; trailer houses destroyed; large
trees snapped or uprooted; railroad box cars
derailed; light object missiles generated; cars
bl own off hi ghway .
SEVERE TORNADO, Severe Damage
158-206 mph
Roofs and some walls torn off frame houses; trains
derailed or overturned; steel framed hangar-ware-
house type structures torn; cars lifted off the
ground .
DEVASTATING TORNADO, Devastating Damage
207-260 mph
Whole frame houses leveled, leaving piles of
debris; steel structures badly damaged; small
flying objects debark trees; cars and trains
thrown or rolled considerable distances, large
missiles generated.
INCREDIBLE TORNADO, Incredible Damage
261-318 mph
whole frame houses tossed off foundations; auto-
mobile-sized missiles generated; incredible phe-
nomena can occur.
319-379 mph
380-445 mph
446-513 mph
514-585 mph
586-659 mph
660-737 mph
738-818 mph
92
Photographs and eyewitness accounts of the larger tor-
nadoes have been used to compile the various classifications.
Table 3.8-6 presents a summary of the historical intensities of
California tornadoes.
Table 3.8-6
Historical Intensity Of California Tornadoes
Based Upon the Fujita Classification Scheme
Class
FO
Fl
F2
F3 or worse
No. of
Storms
8
32
8
0
Percentage (%)
of Observations
16.7
66. 7
16.7
0.0
Hail
Hail results from the formation of spheres of irregular
chips of ice which are produced by convective activity in storm
clouds, such as in cumulonimbus types. Thunderstorms which are
characterized by strong updrafts, high water content, large cloud
drop sizes, and great vertical height extent offer great poten-
tial for hail and ice formation. Hail sizes can range from that
of a few millimeters in diameter to sizes on the order of several
centimeters. Table 3.8-7 presents the incidence of hail and
sleet seasonally and annually at several selected stations in the
Ukiah District.
Table 3.8-7
Stat i on
Areata
Ukiah
Mean Number of Days With Hail/Sleet or Ice
Winter
Spring
Summer
Fall
Annua
1.0
0.0
0.0
0.0
1.0
1.0
0.0
0.0
0.0
1.0
3.8.3
Atmospheric Pressure
Atmospheric pressure, as a climatic parameter, has
little direct effect on the ambient environment but acts as a
climatic control parameter, such that slight variations in atmos-
pheric pressure can induce remarkable variations in general
weather conditions. Pressure gradients regulate wind, and wind
is a major determinant of regional air temperature and moisture
conditions. This also provides a connection between pressure and
dispersion meteorology and ambient air quality. In addition,
pressure systems are often positively correlated with pollutant
93
levels. For example, the semi-permanent eastern Pacific High
Pressure system permits the buildup of high pollutant levels in
Southern California during summer.
Atmospheric pressure is defined as the force exerted by
the atmosphere upon a unit surface area as a consequence of
gravitational attraction on all air molecules. Hence, atmos-
pheric pressure is a measure of the total weight of air situated
above an area in question.
Pressure
is defined in dimensions of fo>rce per unit
area, such as dynes p,er square centimeter (dynes/cm ), pounds per
square inch (lbs/in ), or newtons per square
inch
Meteorologists often
(mb ) , such that , 1 mb
or
refer
newtons
to the
dynes/cm'
equals 1,000 dynes/cm
meter (N /m ) .
ratio as millibars
Pressure measurements are at times expressed in terms of
standards. The average global mean sea 1 e v e,l pressure has been
determined to be 1,013.25 mb (14.7 lbs/ in ). This value of
pressure is often referred to as 1 Standard Atmosphere (Atm).
Similarly, the pressure level of approximately 506 mb (7.35
lbs/in )is referred to as 0.5 Atm.
Atmospheric pressure values are often expressed in terms
of equivalents. Since the atmosphere exerts a force or weight
per unit area , it therefore counter-balances an equivalent
weight. A column of air one square inch in cros s- sect i onal area
extending from sea level to the top of the atmosphere weighs
approximately 14.7 pounds. This weight can be balanced by a
column of mercury having the same cross-sectional area extending
vertically 29.92 inches or 760 millimeters. Therefore, pressure
values can be referred to in units of inches (in) or millimeters
of mercury (mmHg) with the understanding that these values repre-
sent the atmospheric mass that supports a vertical column of
mercury so many inches or millimeters long. As atmospheric
pressure changes in an area, the air mass above that region
changes, and likewise, its ability to counter- bal ance the weight
of the previously described column of mercury.
Table 3.8-8 provides the conversion factors necessary to
transform pressure values into various conventional pressure
units and equivalents. An example demonstrating how to use these
factors is provided below the table.
Figures 3.8-8 through 3.8-11 provide a representive
cross- sect i on of the mean seasonal pressure contours on a na-
tional scale. General atmospheric flow can be estimated by
assuming that winds move nearly parallel to isobars (lines of
equal pressure values). In the northern hemisphere, winds blow
clockwise ( anticycl oni c) around the high pressure centers and
counterclockwise (cyclonic) about low pressure centers.
During the winter months, a high pressure center is
generally situated to the northeast of California and the semi-
permanent Eastern Pacific high pressure system is depressed well
94
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Figure 3.8-8
Mean Winter (January) Pressure Distribution
in the United States
br --!■■ zzkz kiMkii*
Based on 1931-60
r7*r fia m "■"■ ma
Figure 3.8-9
Mean Spring (April) Pressure Distribution
in the United States
96
Figure 3.8-10
Mean Summer (July) Pressure Distribution
in the United States
rl5!i-_*
r NORHAL~SEA ilvEL ^RESSURI, OCTOBErV— -^ ~~ SyTZzE^F
- ] — — (Millibars and Inches)-^ \ \ * i/_3TM.
t?F^^fe^;^ii N«? t>":' ----- ----
>' . i=j^^EfrA l-i^^---.^ - Based on 1931-6
Fi gure 3.8-11
Mean Fall (October) Pressure Distribution
in the United States
97
to the south. This permits moist air to be channeled into the
state from the northwest, west and southwest. The strong poten-
tial for moisture advection during the winter months in Cali-
fornia promotes the "rainy" season. Air quality also tends to be
better during this season.
In the hot summer months, a low pressure center domi-
nates the southwestern portion of the nation. Winds generally
flow inland as the sea breeze regime becomes established. The
Eastern Pacific High Pressure area becomes well entrenched over
California and inhibits the flow of moist, maritime air into the
area, thus permitting the development of high pollutant levels.
Definite pressure cycles occur on numerous time scales.
Mean pressure values experienced in particular regions vary
seasonally and diurnally. Latitude, elevation, topography and
surface albedo collectively influence the mean pressure tenden-
cies registered at a particular location. Variations in atmos-
pheric pressure, at Areata and Ukiah, are depicted on a monthly-
annual basis in Figure 3.8-12 and on a diurnal-seasonal basis in
Figure 3.8-13. The monthly seasonal distribution indicates that
barometric pressure reaches a seasonal maximum in spring at
Areata and in winter in Ukiah. At many stations throughout the
United States winter is the traditional season of maximum high
pressure, however, at Areata the frequent passage of migratory
storm systems prohibits this. Highest surface pressure occurs
during December at Ukiah and in April at Areata. On a diurnal
basis maximum surface pressure is generally observed during the
mid-morning hours at each station with a minimum occurring during
late afternoon. Surface pressure is generally higher at Areata
than at Ukiah during all months except winter, the rainy season.
Ukiah is strongly influenced by surface heating effects and
during other seasons of the year this tends to result in lower
pressure at this station as opposed to the coastal site of
Areata .
3.8.4
Visibility and Fog
Visibility provides an indication of atmospheric clar-
ity. Visibility measurements or estimates are generally ex-
pressed in miles or kilometers denoting the maximum distance at
which one can distinguish objects such as buildings, mountains
and other large landmarks,
numerous physical factors
as well as thermodynamic
more common factors that
visibility and contrast
Visibility reduction is the result of
that include both general air quality
and optical properties. Some of the
play an important role in atmospheric
reduction are air moisture content,
relative humidity, falling rain, snow, hail, blowing dust, sea
spray, high concentrations of suspended particulate matter,
sulfates, oxides of nitrogen, and smoke.
Tables 3.8-9 and 3.8-10 present monthly, seasonal and
annual percentage frequency distributions of visibility for Ukiah
and Areata in the Ukiah District. The data represent
98
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1013
1012
1011
1010
1009
1008
1007
1006
1005
Ukiah
I I L__J I L
M A M J J AS
Month of the Year
0 N
Figure 3.8-12
Monthly-Annual Distribution of Atmospheric Pressure in
the Ukiah District
99
1 2 3 4 5 6 7 • 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
HOUR OF THE DAY
Figure 3.8-13
Diurnal-Seasonal Pressure Variations in the Ukiah District
Analyses based on 8 obs/day
100
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observations of visual range by trained NWS observers at major
airport locations. The data indicate that the frequency of
significantly reduced visibilities is greatest at Areata due
largely to higher moisture levels. Visibility is generally
between 5 and 10 miles during all seasons. The frequency of
significantly reduced visibility is greatest between- June and
October at Areata when fog and stratus frequently occur. At
Ukiah, visibilities are generally between 10 and 2 5 miles.
Poorest visibility occurs in winter when fog occurs most fre-
quent 1 y .
In the mountains, visibility is extremely variable.
Data is very scarce and the BLM is participating in programs
geared to determine visibility on federally-administered lands.
The data presented in Tables 3.8-9 through 3.8-10 is not felt to
be indicative of conditions in rural, mountainous locations.
Air quality can be determined from visibility observa-
tions at particular locations within the district. By elimina-
ting moisture influences on atmospheric clarity, the remaining
reduction in visibility is largely due to suspended to air con-
taminants. Table 3.8-11 presents the number of hours during a
representative five year period that substantial visibility
reduction occurred due to non-moisture effects at Areata and
Ukiah. The criteria denoting a visibility violation in Cali-
fornia was used to develop this table. A violation occurs when
visibility is less than 10 miles and the relative humidity is
less than 70 percent. Once again, data are not available for
much of the mountainous areas in the district.
Table 3.8-11 indicates that at Areata violations of the
California visibility standard occur primarily during the fall
and winter months when stagnation episodes occur. At Ukiah,
summer and fall provide the maximum frequency of violations of
the standard. Photochemical processes occur most actively during
this season resulting in visibility impairment at Ukiah. The
frequency of violations is generally greater at Ukiah then at
Areata which is greatly impacted by the onshore flow of clean,
maritime Pacific air.
Fog
Considerable visibility reduction is directly related to
ambient moisture levels. Table 3.8-12 presents the mean number
of days that visibility is less than one-quarter mile due to the
presence of heavy fog.
Table 3.8-12 indicates that the frequency of fog is
greatest during the winter months at all stations with the excep-
tion of Areata. At Eureka, San Francisco, Ukiah, and Sacramento
the frequency of fog reaches a maximum during the December -
January time frame when the passage of migratory storm systems
reaches a maximum. The frequency of fog during the winter months
increases with northward progression along the coast. Areata
103
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shows a maximum frequency of heavy fog during the summer and fall
months, with heavy fog being not uncommon during any month of the
year .
Fog, is associated with moist, cool, surface air masses
at the point of saturation. Fog can be classified i n tro numerous
types according to the physical processes responsible for its
development. Fog types that are common in the Ukiah District
i ncl ude :
0 Radiational
• Advection
• Fronta 1
A very common type of land fog often experienced in the
mountian valleys known as radiational or surface inversion fog,
is produced by the radiational cooling of relatively shallow
layers of calm, humid air, overlying a chilled land surface.
This type of fog development requires certain nighttime condi-
t i ons whi ch i ncl ude :
• Stabl e surface ai r
• Light or calm winds
• Clear skies
Stable surface conditions inhibit vertical diffusion of fog
formed at the surface. Light winds promote radiational fog
development by limiting mixing. Cloudless skies promote fog
since they allow rapid heat loss from the surface thus permitting
the ground to cool rapidly, even below surface air temperatures.
Radiational fog occurs in low-lying areas as cool, dense
air drains into valleys and low-lying regions. Often, hilly
areas will remain clear while adjacent lowlands are foggy.
Radiational or ground fog deepens from the ground upward at night
and is dissipated during the day by the warming sunlight from the
top downward.
Advection fog, unlike radiational fog, requires consid-
erable air movement to promote formation. It simply requires
that warm moist air masses be moved over cold surfaces and this
most commonly occurs over ocean and coastal locations during
summer. During this period, pressure gradients between oceanic
and inland air masses are at a maximum, thus promoting inland
movement (sea breeze). At coastal locations, warm moist air is
channelled over and mixed with cold, moist, surface maritime air.
Condensation of water vapor in the ambient air is promoted, thus
forming fog. This type of coastal sea fog is most commonly
observed during the summer months.
The frequency of occurrence of fog by month in the
Ukiah District is presented in Figure 3.8-14. The figure pro-
vides fog frequency at selected key stations in of the Ukiah
District.
106
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Figure 3.8-14
Frequency of Fog Development in the
Ukiah District
107
3.8.5
Ocean Temperatures
Seasonal variations of ocean temperatures have a de-
finite effect on the climatology of coastal areas. During the
winter months, ocean temperatures are near and often- above am-
bient air temperatures. In the summer, however, ocean tempera-
tures are generally below ambient air temperatures. The physical
effect of ocean temperatures on mean seasonal air temperatures at
coastal locations in comparison to inland areas is outlined in
the temperature section of this report. Mean monthly ocean tem-
perature contours are presented in Appendix B. The mean monthly
temperature change from the maximum to the minimum is 4.4°C
(7.9°F) at San Francisco and only 2.2°C (4.0°F) at Cape Mendo-
cino. Table 3.8-13 presents the mean monthly ocean temperatures
for San Francisco and Cape Mendocino. Generally, ocean tempera-
tures are warmer at San Francisco than at Cape Mendocino during
all seasons. Mean annual temperatures for much of the California
coastline are presented in Figure 3.8-15. Generally, the coastal
waters along the Ukiah District average about 52 F.
108
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10 METfR TEMPERATURE CO
IS-YEM MEAN. 1*50-1962
i ■ i I i i i i
T*n-m«T«r temporotvr* (*C); 13-yoar own, 1950-62. In-
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Figure 3.8-15
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C = J (uF-32)
110
3.9
URBAN EFFECT UPON METEOROLOGIC PARAMETERS
There is hardly a meteorologic element that can be named
that is not influenced to some extent by cities. It is, however,
difficult to separate urban effects from microclimatologic ef-
fects since yery few measurements have been made with the specif-
ic aim of comparing urban and non-urban measurements. There are
several causes for the differences between urban and open country
climates. One of these is the alteration of the surface, e.g.,
the change from meadow, forest or swamp to buildings and streets
of concrete, brick, steel, and asphalt. Not only does this cause
changes in reception and reflection of solar radiation and evap-
oration, but also in the roughness of the surface over which the
wind moves. Another change involves the production of a sizable
quantity of heat due to combustion processes carried out in the
city and the addition of material to the atmosphere in the form
of dusts, gases, and vapors which change the atmosphere's compo-
sition in the vicinity of cities.
Temperature
The comparison of temperatures within cities with those
outside reveal that city temperatures, especially at time of
minimum, are higher (Mitchell, 1961). Also during the period
right after sunset, the city temperature does not cool as rapidly
as does the country air due to heat content of buildings and
radiation between buildings, rather than toward the sky. Between
sunrise and noon, urban and non-urban temperatures are nearly the
same (Landsberg, 1956). The influence of the city extends in
the vertical on the order of three times the height of the build-
ings (Duckworth and Sandberg, 1954). The average heat island
effect over New York City extends to 300 meters (-1000 feet) and
has been observed as high as 500 meters (-1650 feet) (Bernstein,
1968). Also, the change of temperature with height is quite
different over the city, especially at night. In the open coun-
try, radiation inversions form frequently, whereas in the city,
isothermal or neutral conditions frequently exist through the
night with a radiation inversion layer above the city (DeMarrais,
1961) .
Since temperatures in the city are warmer than those of
the surrounding countryside, the city's heating requirements are
less by as much as 10%. Variations between city and country
temperatures are extremely noticeable at northern latitudes when
the countryside is covered with snow which has melted in the
city.
Preci pi tat i on
Precipitation is one of the most variable meteorological
elements and, because of this, it is difficult to establish
significant differences between urban and non-urb-an areas.
However, numerous studies have been made which show either great-
er precipitation amounts and/or greater frequency of precipita-
tion within cities. Schmauss in 1927 showed 11 percent increase
of days with small amounts of precipitation occurring in Munich
compared to stations outside the city. Bolgolepow in 1928 re-
ported an increase in precipitation of 10 percent in Moscow
compared to a country station for 17 years of record. Ashworth
in 1929 noted the increase of average annual precipitation over 3
decades amounting to 13 percent. He also noted less increase for
Sundays than for weekdays. Wiegel in 1938 using a 35 year re-
cord, noted a 5 percent increase in precipitation, as well as a
12 to 18 percent increase in the number of days with precipita-
tion for the Ruhr area of Germany. These references are all
reported in Landsberg (1956). Landsberg also reports a study for
Tulsa where topographical effects are at a minimum and the urban
area is confined to a rather definite area. In addition to a
precipitation increase within the city over a 70 year period,
there was an increase of 7 percent in the city compared to sur-
roundings for a 14 year period.
Two more recent studies by Changnon (1961a, 1961b)
indicate there may be some urban effect upon preci pi tai ton over
Chicago and the moderate- si zed communities of Champaign, and
Urbana, Illinois.
The principal suspected causes of the increase of pre-
cipitation over cities is the increase of condensation nuclei
over cities due to air pollutants and the increased turbulence
caused by increased surface roughness. Although water vapor is
added to the air from combustion sources, this is not expected to
add significantly to the amount of precipitable water or to evoke
a major effect.
Snow
Precipitation in the form of snow indicates to some
extent the influence of temperature in the urban area. Kossner
in 1917 and Maurain in 1947 indicated greater frequencies of
snowfall outside as compared to within Berlin and Paris, respec-
tively. On the other hand, Kratzer in 1937 in Munich reported
occurrances of snow within the city
surroundings, and Keinle in Mannheim,
reported that snow fell from a fog
successive days in January 1949 while
area. It is probable that this was
nishing condensation nuclei for supercooled water vapor. These
references appear in Landsberg (1956) who also estimates a 5%
average decrease in snowfall for urban areas (Landsberg, 1968).
when none occured in the
a heavy industry location,
and stratus layer on two
none fell outside the urban
due to air pollutants fur-
112
Cloudiness
From cl i matol og i cal records there seems to have been a
slight increase in cloudiness over the years but this has been so
slight (less than 1/10 of mean sky cover) that for so subjective
a measure as sky cover this may not be significant. Any increase
may be primarily due to city fogs, as increases in early morning
cloud cover seems to be greatest. Nearly all large cities show a
decrease in the number of clear days over that obseved in adja-
cent rural areas. The primary effects may be expected to be due
to addition of condensation nuclei by air pollution and the
release of additional water vapor. Kratzer in 1937 in Munich
indicated an 8 percent increase in summer cloudiness compared to
a 3 percent increase in winter cloudiness over the city (Lands-
berg, 1956). This may indicate that surface roughness and there-
fore, increasing turbulence, may play a part in the formation of
cumulus type summer clouds.
Wind
Because of the general increase of the size of the
roughness elements in the city over that in the rural areas, wind
speeds are decreased within the city. Also the frequency of
calms is increased on the order of 5 to 20 percent (Landsberg,
1956). Recently, Pooler (1961) has shown that under conditions
of light stable flow, an inflow of air toward the center of the
city of Louisville occurs (heat island effect). In addition to
the decrease of wind speed in cities, there is of course channel-
ing of the wind in the canyons formed by alternating streets and
groups of buildings.
Radiation
The decrease of solar radiation within cities as com-
pared to rural areas is on the order of 15 to 20 percent. This
is due to the absorption, reflection, and scattering of particles
in the atmosphere, and the absorption of gases. These particles
and gases are primarily the result of air pollution. The radia-
tion most affected is the ultraviolet with the infrared being
least affected. This is important because of the bactericidal
effect of ultraviolet radiation.
Recently, McCormick (1960) has begun measuring of the
attenuation of the solar beam at 0.5 micron wave length in order
to have an objective measure of the entire pollution layer. In
terms of duration of sunshine, Landsberg (1968), shows a decrease
in the range of 5-15% in urban areas. Randerson (1970) has
showed an average of 23% loss in intensity of light attributed to
pollution in Houston, Texas.
113
Visual Range
The decrease of visibility in urban areas is probably
the most noticeable of meteorological differences between urban
and rural areas. Comparisons between hourly observations of
visibility at city locations and at rural locations (-Landsberg,
1956) have shown higher frequencies of fog, smoke, and low visi-
bilities than in neighboring rural areas.
Holzworth and Maga (1960) analyzed visibility measure-
ments from California locations to determine if trends which
might be caused by increases in air pollution were noticeable.
Results indicated that several cities showed trends toward lower-
ing visibilities. Other showed lowering visibilities until
efforts at controlling certain pollutants were made, after which
no trend was discernible.
114
3.10 GENERAL ASSISTANCE IN CLIMATIC PROBLEMS
REFERENCES
t Abstracts
Meteorological and Geoast rophys i cal
Abstracts
American Meteorological Society
45 Beacon Street
Boston , Mass .
• Periodicals
Bulletin of the American Meteorological
Soc i ety
American Meteorological Society (See above)
Journal of Applied Meteorology
American Meteorological Society (See above)
Journal of the Atmospheric Sciences
(formerly Journal of Meteorology)
American Meteorological Society (See above)
Monthly Weather Review
U.S. Dept. of Commerce
Weather Bureau, Washington, D.C.
Quarterly Journal of the Royal Meteorological
Society
Royal Meteorological Society
49 Cromwel 1 Road
London , S. W . 7
Weather
Royal Meteorological Society (See above)
Weatherwise
American Meteorological Society (See above)
Books
American Meteorological Society, On Atmospheric
Pollution,
Meteorol ogical Monographs, 1_, 4, Nov. 1951.
Byers, H.R. General Meteorology,
McGraw-Hill, New York, 3rd ed. 1959.
Geiger, R. (Translated by Scripta Technica Inc.)
The Climate Near the Ground.
Rev. ed., Harvard University Press, Cambridge,
Mass. 1965.
115
Haltiner, G.J.; and Martin,
Physical Meteorology.
McGraw-Hill, New York.
F. L. Dynami cal and
1957
Hess, S.L. Introduction to Theoretical Me-teorology.
Henry Holt, New York, 1959.
Hewson, E.W.: and Longley, R.W. Meteorol ogy ,
Theoretical and Applied
Wiley, New York. 1944.
Professional Meteorological Consultants
Professional meteorologists advertise their services in
the Professional Directory section of the Bulletin of the Ameri-
can Meteorological Society. In the May 1979 Bulletin, 83 such
firms and individuals were listed. The American Meteorological
Society has in the last several years instituted a program of
certifying consulting meteorologists. Of the 83 professional
services listings in the Bulletin, 40 list Certified Consulting
Meteorologists.
Local U.S. National Weather Service Office
A wealth of meteorological informaiton and experience is
available at the local city or airport Weather Service Office
pertaining to local climatology, pecularities in local micro-
meteorological conditions including topographic effects, and
exposure and operating characteristics of meteorological instru-
ments .
Contract Work
Many universities do contract work for private organi-
zations and for government agencies on meteorological problems.
116
BIBLIOGRAPHY
Bernstein, R . D . , Observations of the Urban Heat Island Effect in
New York City. J. Appl. Meteor. 7_, 4:575-592, Aug., 1968.
California Energy Commission, California Solar Data Manual ,
Sacramento, California, 1978.
California Snow Survey Service, Historical Data of Cooperative
Snow Survey Measurements , available through the State of
California Resources Building, Sacramento.
Changnon, Stanley A. Jr., "Precipitation Contrasts Between the
Chicago Urban Area and An Offshore Station in Southern Lake
Michigan", Bull, of the American Meteorol. Soc., 4_2, 1, 1-10,
Jan. 1961.
Climatic Atlas of the United States
Climatological Study; Southern California Operating Area, Fleet
Weather Facility, San Diego, California.
DeMarrais, Gerard A. "Vertical Temperature Difference Observed
Over an Urban Area", Bull, of the Amer. Meteorol. Soc., 42 ,
8, 548 - 554, Aug. 1961.
Duckworth, F.S. and Sandberg, J.S. "The Effect of Cities Upon
Horizontal and Vertical Temperature Gradients", Bull, of the
Amer. Meteorol. Soc, 35., 5, 198-207, May 1954.
Elford, C. Robert, Climate of the States: Climate of California,
U.S. Department of Commerce, ESSA, 1970.
Felton, Ernest L., C a 1 i f o r n i a ' s Many Climates , Pacific Books
Publishers, Palo Alto, California, 1968.
Findeison, W., Meteorol. Z. 5_6, 453 1937.
Frederick, R.H. Weather Data for Air Pollution-Available, Analy-
zed and Inexpensive. J. of Air Pollution Control Assoc.
14:2, 60-65. 1964.
Fujita, T.T., 1970a: Estimate of a Real Probability of Tornadoes
from Inflationary Reporting of Their Frequencies. Dept. of
Geophys. Sci., Univ. of Chicago, SMRP Research Paper No. 89.
Go.odridge, Dr. James, personal notes, Dept of Water Resources,
State of California, Sacramento, California.
Hoecker, W.H., 1961: Three-Dimensional Pressure Pattern of the
Dallas Tornado and Some Resultant Implications. Mon . Wea .
Rev. , 89, 12, 533-542.
117
Holzworth, G.C. and Maga, J. A., "A Method for Analyzing the Trend
in Visibility", J. Air Poll. Control Assoc, 1_0, 6, 430-435,
Dec. 1960.
Houghton, H.G., "On the Annual Heat Balance of the Northern
Hemisphere" J. Meteorol, l±t 1, 1-9. Feb. 1954.
Landsberg, H.E. "The Climate of Towns" in Man's Role in Changing
the Face of the Earth, Thomas, W.L. Jr." ecL Univ. of Chi cago
Press, 1956.
Landsberg, H.E. Climate and Urban Planning Pres. WMO Symposium of
Urban Climates and Building Climatology. Brussels, October
19, 1968.
Lynn, Ronald J., Seasonal Variation of Temperature and Salinity
at 10 meters in the California Current, Bureau of Commerc i a 1
Fisheries, Tuna Resources Laboratory, La Jolla, California.
McCormick, R.A. and Tabor, E.C. "U.S. Weather Bureau-Public
Health Service Precipitation Chemistry and Aerometric
Studies" presented at the 12th General Assembly, Int. Union
of Geodesy and Geophysics, Helsinki, Finland, July 26 - Aug.
6, 1960.
Mitchell, J. Murray, Jr. "The Temperature of Cities", Weather-
wise, 14, 6, 224-229, December 1961.
National Data Buoy Center, National Ocean Survey, National Ocean-
ic and Atmospheric Association, Environmental Conditions
within Specified Geographical Regions: Offshore East and
West Coasts of the United States and in the Gulf of Mexico.
Palmen, E. , Quart, J. Roy. Meteorol Soc, 7_7_337. 1951.
Pooler, Francis, Jr. "Stable Airflow Patterns at Louisville,
Ky . " , Presented at Joint Meeting of Amer. Geophy. Union-Amer.
Meteorol. Soc, Wash., D.C., April 18-21, 1961.
Randerson, D. , A Comparison of the Spectral Distribution of Solar
Radiation in a Polluted and a Clear Air Mass. JAPCA, 20 ,
8:546-548, Aug., 1970.
Reynolds, G.W. 1970a: A Practical Look at Tornado Forces. Tech.
Paper No. 3, Utah State Univ. Presented Conf. on Tornado
Phenomenology and Related Protective Design Measures, Univ.
- of Wisconsin, April 26-28.
Smith, T.B., Mirabella, V.A. 1972: Characteristics of California
Tornadoes ., For University of California, Ernest Q. Lawrence
Livermore Laboratory, 7 January 1972.
State of California Air Resources Board, "Climate of the Sacra-
mento Valley Air Basin."
118
State of California, Department of Water Resources, 19 7 8 Cali-
fornia Snow Survey Measurement Schedule, California Coopera-
tive Snow Surveys, 1978.
State of California, The Resources Agency, Department of Water
Resources, California Sunshine - Solar Radiation Data; May
1978.
State of California, The Resources Agency, Department of Water
Resources, Vegetative Water Use in California, 1974, Bulletin
No. 113-3, April 1975.
Thorn, H.C.S., 1970b: Estimate of Maximum Wind Speeds of Tor-
nadoes in Three Northwestern States. Dept. of Geophys. Sci.,
Univ. of Chicago, SMRP Research Paper No. 92.
Thorn, H.C.S., 1970b: Tornado Force Considerations for Construc-
tion Decisions. Utah State Univ., Logan, Utah, 3pp.
Thorn, H.C.S., 1963
730-736.
Tornado Probabilities. Mon . Wea ♦ Rev . , 9 1,
U.S. Department of Commerce, ESSA, Climates of the States:
Climate of California, CI imatography of the United States
60- Y . , Silver Springs, Maryland.
U.S. Department of Commerce, ESSA, CI i m a t e s of the States -
C 1 i mate of California , Silver Springs, MD, 1970.
U.S. Department of Commerce, NCC, Supplement 1 to Climate of
California, CI i matography of the United States No. 60. Ashe-
ville, N.C. , 1977.
U.S. Department of Commerce, N0AA, CI j ma t o 1 o g i c a 1 D a t a - C a 1 i -
f orni a , National Climatic Center ~ Ashv i 1 1 e , N.C.
U.S. Department of Commerce, N0AA, Comparative Climatic Data
Through 1976 , National Climatic Center, Asheville, N.C.
U.S. Department of Commerce, N0AA, Local C 1 i matol ogi cal Data,
1976, Blue Canyon, San Franc i sco/ Federal Office Buildings,
San Francisco International Airport, Oakland International
Airport, Bishop, Fresno, Stockton, Sacramento, National
Climatic Center, Asheville, N.C.
U.S. Dept. of Commerce, National Oceanic and Atmospheric Adminis-
tration, National Weather Service, NOAA Atlas II: Precipita-
tion Atlas of the Western United States, Vol. XI - Califor-
n i a , Si 1 ver Springs, Maryland.
U.S. Department of Commerce, National Oceanic and Atmospheric
Association, TDF-14 Hourly Observations, Monterey, Stockton,
Fresno, Bishop California, National Climatic Center, Ashe-
ville, N.C.
119
U.S. Dept.of Commerce, Technical Paper No. 19: Mean Number of
Thunderstorm Days in the United States, Washington, D.C.
1952.
U.S. Department of Commerce, Weather Bureau, Summary of Hourly
Observat i ons , Sacramento, Fresno, San Francisco, Oakland,
C a 1 i f o r n i a .
U.S. Environmental Protection Agency, "Air Pollution Meteorolo-
gy", Control Programs Development Division, Research Triangle
Park, North Carolina, 1973.
World Wide Airfield Climatic Data, Vol VIII, West Coast, Western
Mountains, and Great Basin States.
120
3. 11
GLOSSARY OF TERMS
Abscissa
Absorpt i on
Advect i on
Air Pollution
Meteorology
The Horizontal coordinate or axis of any
graph; usually denoted by X..
The process in which incident radiant energy
is retained by a substance.
The process of transport of an atmospheric
property solely by the mass motion (i.e.,
wind) of the atmosphere.
That aspect of meteorology concerned with
atmospheric dispersion characteristics.
Aitken Nuclei
Al bedo
Annual Moi st ure
Deficit
Ant i cycl one
Attentuation
Ceiling
Centri petal
Accel erat i on
CI i mate
The microscopic particles in the atmosphere
which serve as condensation nuclei for droplet
growth. These nuclei are both liquid and
solid with diameters of tens of microns or
sma 1 1 er .
A measure of the part of the incoming solar
radiation which is reflected from the earth
and the atmosphere.
The moisture deficit of a month is the poten-
tial evapotranspiration less the rainfall and
stored soil water. The sum of the appropriate
months is the annual moisture deficit.
Movements of air traveling in a clockwise
direction (in the northern Hemisphere). Since
anticyclone circulation and relative high
atmospheric pressure usually coexist, the
terms anticyclone and high pressure are often
used interchangeably.
The process by which energy decreases with
increasing distance from the energy source
The height of the lowest layer of clouds or
other obscuring phenomena (e.g., dust).
During clear weather, the ceiling in unlimit-
ed. With fog, the ceiling is obscured.
Acceleration on a particle moving in a curved
path, directed toward the center of curvature
of the path.
The average condition of the weather at a
place over a period of years as exhibited by
temperature, wind velocity, and precipitation.
121
Compress i onal
Heating
Condensat i on
Condensation
Nuclei
Continental
CI i m a t e
Convect i on
Cooling Degree
The disturbance of a fluid (e.g., air) such
that the pressure and density and, therefore
temperature, increase in the direction of
mot ion.
The physical process by which a vapor becomes
a liquid or a sol i d .
A particle, either liquid or solid, upon which
condensation of water vapor begins in the
atmosphere .
The climate that is characteristic of the
interior of a land mass. It is marked bylarge
annual, daily and day to day ranges of temper-
ature, humidity and precipitation.
In general, mass motions within a fluid (e.g.,
air) resulting in transport and mixing of the
properties of that fluid.
A form of degree day used to estimate the Days
energy requirements for air conditioning
or refrigeration. One cooling degree-day is
given for each degree that the daily mean
temperature deports above a base of 75°F.
Coriolis Force
A deflective force resulting from
rotation; it acts to the right of
tion in the Northern Hemisphere
left in the Southern Hemisphere.
the earth ' s
wind direc-
and to the
Crystal 1 i zat i on
Cumul oni mbus
Cumul us
Cycl ones
Cyclonic Storms
A particle which serves as a nucleus in the
formation of ice crystals in the atmosphere.
A principal cloud type, exceptionally dense
and vertically developed, occurring either as
isolated clouds or as a line or wall of clouds
with separated upper portions.
A principal cloud type in the form of indi-
vidual, detached elements which are generally
dense and possess sharp non-fibrous outlines.
Movements of air traveling in a counterclock-
wise direction (in the northern Hemisphere).
Since cyclonic circulation and relative low
atmospheric pressure usually coexist, the
terms clclone and low pressure system often
are used interchangeably.
Large storm systems (50 to 900 miles in diam-
eter or more) characterized by air rotating
around a center of low pressure. More common
122
Dew Point
in winter than summer. Rainfall and snowfall
associated with such storms may be light, but
may persist for two to three days or longer.
The temperature to which air must be cooled in
order for saturation to occur.
Dew Point
Depressi on
Di vergence
Dry Bulb
Temperature
Eddy Vi scosi ty
The difference between the air temperature and
the dew poi nt .
The expansion or spreading out of a vector
field (e.g., velocity field).
The ambient temperature of the air as measured
by a dry-bulb thermometer.
The turbulent transfer of momentum by eddies
(a glob of fluid with a fluid mass that has a
life history of its own) giving rise to fluid
friction.
El ectromagnet i c
El ectromagnet i c
Waves
E vaporat i on
Evapo-
t ranspi rati on
Ex posure
The ordered array of all known electromagnetic
Spectrum radiations, extending from the
shortest cosmic rays, through gamma rays,
x-rays, ultraviolet light, visible/light,
infrared radiation, and including microwave
and all xother lengths of radio energy.
Energy propagated through space or through
material media in the form of an advancing
disturbance in electric and magnetic fields
exi st i ng in space .
The physical process by which a liquid or
solid is transformed to the gaseous state.
The combined processes by which water is
transferred from the surface of the earth to
the atmosphere; e vaporat i on of liquid or solid
water plus t ranspi rat i on from plants.
The general surroundings of a site, with
special reference to its openness to winds and
sunshine.
Fall Velocity
First Order
Stations
That limited velocity attained by a body
freely falling in air when the resisting force
is equal to the gravitational force.
A meteorological station at which automatic
records and hourly readings of weather ele-
ments are made.
123
Free Atmosphere
Friction Layer
Frictional Drag
Front
Frost-Free
Period
Fuj i ta Seal e
Gradient
Greenhouse Effect
Growing Season
Heat Isl and
Heating Degree
Hygroscopic
Nuclei
That portion of the earth's atmosphere, above
the planetary boundary layer, in which the
effects of the earths surface friction on the
air motion are negligible.
The term is interchangeable with planetary
boundary layer and surface boundary layer and
refers to the layer between the surface and
the free atmosphere.
The frictional impedence offered by air to the
motion of bodies passing through it.
In meteorology, generally, the interface or
transition zone between two air masses of
different density.
The frost-free period refers to the length of
the growing season as determined by the number
of days between the last frost (i.e., 32°F) in
spring and the first frost in fall.
A scale baed upon maximum wind speed to define
the intensity of a tornado.
The rate of change of a parameter as a func-
tion of di stance .
The heating effect exerted by the atmosphere
upon the earth by virtue of the fact that the
atmosphere absorbs and reemits infrared radia-
tion.
Generally, the period of the year during which
the temperature of cultivated vegetation
remains sufficiently high to allow plant
growth (Usually synonymous with Frost-Free
Period) .
The accumulation of heat by large, man-made
structures such as cities, resulting in con-
siderable differences in temperature in com-
parison with surrounding areas, particularly
at night.
A form of degree-day used as an indication Day
of fuel consumption; in the United States, one
heating degree day is given for each degree
that the daily mean temperature departs below
a base of 65°F.
Nuclei with a marked ability to accelerate the
condensation of water vapor.
124
I nf rared
(Radiation)
Inversion
Ions
I sobars
I sohyet
I sot hermal
Jet Stream
Jul i an Days
Killing Frost
Kinetic Energy
Lake Evaporation
Langl ey
Lapse Rate
Electromagnetic radiation lying in the wave-
length interval between visible radiation
(light) and microwave radiation.
An increase in temperature with height--a
reversal of the normal decrease with height in
the troposhpere; may also be applied to other
meteorological properties.
In atmospheric electricity, any of several
types of electrically charged submi croscopi c
particles normally found in the atmosphere.
Lines of equal or constant pressure.
A line drawn through geographical points
recording equal amounts of precipitation
during a given time period or for a particular
storm.
Of equal or constant temperature, with respect
to either space or time; more commonly, tem-
perature with height; a zero lapse rate.
Relatively strong winds concentrated in a
narrow stream in the atmosphere.
A calendar system based upon the sequantial
numbering of each day of the year up to 365
with no monthly delineation.
The frost sufficiently severe to damage the
vegetation of an area. For the purpose of
this report, when temperatures are 28°F or
1 ess .
The energy which a body possesses as a conse-
quence of its motion.
Evaporation from a lake large enough and deep
enough so that evaporation from most of its
surface is unaffected by the temperature of
the surrounding and underlying land.
Unit of energy per unit area commonly employed
in radiation. One Langl ey is equal to one
gram - calorie per square centimeter. The
unit was named in honor of the American scien-
tist, Samuel P. Langley (1834-1906) who made
many contributions to the knowledge of solar
radiation.
The decrease of an atmospheric variable (com-
monly, temperature) with height.
125
Latent Heat
Leeward
The amount of heat absorbed (converted to
Kinetic Energy) during the processes of change
of liquid water to water vapor, ice to water
vapor, or ice to liquid water; or the amount
released during the reverse process-es. Four
such processes are condensation, fusion,
sublimation and vaporization.
The downwind side of an obstacle.
Marine
( al so Maritime)
Mechani cal
Mediterranean
Climate
Meridional
A regional climate which is under the predomi-
nant influence of the sea. A marine climate
is characterized by small diurnal and annual
ranges in temperature.
Turbulence due to the roughness of the surface
over which the air is passing.
A type of climate characterized by hot, dry,
sunny summers and a winter rainy season.
Longitudinal; northerly or southerly; opposed
to zonal .
Meso Scale
Mi crometeorol ogy
(also, Micro-
cl imatol ogy)
That portion of meteorology which deals with
atmospheric phenomena on a scale larger than
that of micrometeorol ogy but smaller than the
cyclonic scale ( - 5 to 50 miles).
That portion of the science that deals with
the observation and exploration of the small-
est scale physical and dynamic occurrences
within the atmosphere.
Moisture Deficit
The moisture deficit of
tial evapotranspiration
stored soil water.
a month is the poten-
1 ess the ra i nf al 1 and
Mol ecul ar
Friction
Whenever the surface of one molecule slides
over that of another, each molecule exerts a
frictional force on the other, parallel to the
surfaces .
Norther
A strong, very dry, dusty, northerly wind
which blows in late spring, summer and early
fall in the Valley of California or in the
West Coast when pressure is high over the
mountains to the north.
Orographi c
Li f t i ng
Palmen ' s Model
The lifting of an air current caused by its
passage up and over mountains.
A model describing the general meridional
circulation of the earth's atmosphere broken
into three cells.
126
Pan Evaporat i on
The standard way to measure evaporation of
water by using small pans exposed to the
atmosphere. The standard Class A land pan is
four feet in diameter and ten inches deep,
raised six inches from the ground so that air
can circulate around it.
Parameter
Pert urbat i on
PI anc k ' s Law
In general, any quantity that is not an inde-
pendent variable. The term is often used in
meteorology to describe almost any meteorolo-
gical or climatological quantity or element.
Any departure introduced
steady state of a system.
into an assumed
An expression for the variation of monochro-
matic emittance as a function of wavelength of
black-body radiation at a given temperature.
It is the most fundamental of the radiation
1 aws .
Pluvial Indices
Pol ar Front
Potential Energy
Potent i al
Evapo-
transpiration
Pressure
Gradient Force
Radiational Fog
Rad i osonde
Rainfall
Frequency
An index showing the amount of precipitation
falling in one day, or other specified period,
that is likely to be equalled or exceeded at a
given place only once in a given return period
(often , 100 years ) .
The s em i - pe rm a nent , s em i - c ont i n uou s front
separating air masses of tropical and polar
origins.
The energy which a body possesses as a conse-
quence of its position in the field of gravi-
ty.
Combined evaporation from the soil surface and
transpiration from plants when the water
supply in the ground is unlimited.
The force due to
within a fluid mass
differences
(e.g. , air) .
in pressure
A major type of fog, produced over a land area
where radiational cooling reduces the air
temperature to or below its dew-point.
A balloon-borne instrument for the simultane-
ous measurement and transmission of meteor-
ological data .
The number of times during a specific period
of years that precipitation of a certain
magnitude or greater, occurs or will occur at
stat i ons .
127
Snow Pack
Sol ar
I n s o 1 a t i o n
The amount of annual accumulation of snow at
higher elevations in the Western United
States, usually expressed in terms of average
water equivalent.
The total radiant energy from the sun incident
on a unit area of a horizontal plane located
at the surface of the earth.
Solar Radiation
The total electromagnetic radiation emitted by
the sun .
Squall Line
Any non-frontal line or narrow band of active
thunderstorms .
Stagnation
Epi sodes
Standard
Atmosphere
Storm Track
Stratosphere
Periods of poor atmospheric ventilation re-
sulting in the potential for substantial
pol 1 utant levels.
A hypothetical vertical distribution of atmos-
pheric temeprature, pressure and density,
which by international agreement is taken to
be representative of the global atmosphere
(59°F and 29.92 in. of mercury at sea level).
The path followed
pheric pressure.
by a center of low atmos-
The atmospheric layer above the tropopause,
average altitude of base and top, 7 and 22
miles respectively; a \/ery stable layer char-
acterized by low moisture content and absence
of clouds.
Stratus
Supercool ed
Supersaturation
A principal cloud type in the form
layer with a rather uniform base.
of a gray
The reduction of temperature of
below the melting point of that
solid phase; that is, cooling
nominal freezing point.
any liquid
substance' s
beyond i t s
In meteorology, the condition existing in a
given portion of the atmosphere, when the
relative humidity is greater than 100 percent.
Synoptic
In general, pertaining to or affording an
overall view. In meteorology, it refers to
the use of meterol og i cal data obtained simul-
taneously over a wide area for the purpose of
presenting a comprehensive and nearly instan-
taneous picture of the state of the atmos-
phere .
128
Synopt i c Scale
Terrestrial
Radiation
Weather patterns associated with high and low
pressure systems in the lower troposphere,
i.e., 1 arge seal e .
(also called earth radiation, eradiation) The
total infrared radiation emitted from the
eart h ' s surface .
Thermal
Buoyancy
Transpi rat i on
Tropopause
Tropos phere
Buoyancy attributable to a local
temperature .
l ncrease l n
Tul e Fog
Turbul ence
Ultraviolet
(radiation)
Water
Equivalent
Wa vel ength
Weather
The process by which water in plants is trans-
ferred as water vapor to the atmosphere.
The transition zone between the troposphere
and stratosphere, usually characterized by an
abrupt change of lapse rate.
That portion of the atmosphere from the
earth's surface to the tropopause; that is,
the lowest 6 to 12 miles of the atmosphere.
The troposphere is characterized by decreasing
temperature with height and by appreciable
water vapor .
A persistent, dense fog
Valley of California.
common in the Central
A state of fluid flow in which the instanta-
neous velocities exhibit irregular and appar-
ently random fluctuations so that in practice
only statistical properties can be recognized
and subjected to analysis.
Electromagnetic radiation of shorter wave-
length than visible light but longer than
x- rays .
The liquid water present within a sample of
snow .
In general, the mean distance between maxima
of a roughly periodic pattern (e.g., light).
The state of the atmosphere mainly with re-
spect to its effects upon life and human
activities. As distinguished from climate,
weather consists of the short term (minutes to
months) variations of the atmosphere. Popu-
larly, weather is thought of in terms of
temperature, humidity, precipitation, cloudi-
ness, brightness, visibility and wind.
129
Wet Bulb
Temperature
The temperature measured by a wet, muslim-
covered bulb thermometer. The temperature an
air parcel would have if cooled adiabatically
to saturation at constant pressure by evapora-
tion of water into it.
Wind Roses
Diagrams designed to show the distribution of
wind speed and direction experienced at a
over a considerable period.
form consists of a circle from
lines emanate,
The length of
the frequency
the frequency
given 1 ocat i on
The most common
which 8 or 16
compass poi nt .
proportional to
that direction;
one for each
the line is
of wind from
of calms is
entered in the center.
Zonal
Latitudinal; easterly or westerly; opposed to
meridional .
130
4. DISPERSION METEOROLOGY
4.1
INTRODUCTION
An understanding of the dispersion potential of a region
is essential in determining the impact of both existing and
proposed sources of ground level and elevated emissions of pollu-
tants. Areas that are plagued with poor dispersion conditions
for extended periods of time are apt to suffer stringent limita-
tions on land use and industrial development. Under such poor
dispersion conditions, seemingly insignificant sources of pollu-
tion can result in excessive concentrations over large areas. As
discussed in Section 6, The Clean Air Act Amendments of 1977
impose strict regulatory requirements on new sources of air
pollution in areas with high ambient pollutant concentrations.
The dispersion potential within the Ukiah District has
been developed through the maximum utilization of available data.
The following sections describe the dispersion meteorology of the
Ukiah District in terms of the following analyses:
Data Sources
Prevailing Winds
Atmospheric Stability
Mixing Heights and Inversions
Typical and Worst-Case Conditions
Air Basins
Fi re Weather
General Dispersion Modeling
Surface data suitable for use in the analysis of the
Ukiah District dispersion meteorology are derived primarily from
the National Weather Service (NWS) first-order meteorological
stations. The availability of mixing height, inversion and winds
aloft data is limited to those stations that take routine meas-
urements of upper air winds and temperatures. There are no NWS
station of this type in the District. However, upper air winds
and temperature data are also available at other sites as part of
a program being conducted by the California Air Resources Board
(CARB). Additional data from lower-order NWS or other govern-
mental and special interest stations have been reviewed and
included where they provide additional significant information
regarding the characterization of the dispersion meteorology of
the Ukiah Di st ri ct .
Section 4.2 provides a review of the general principles
of dispersion meteorology. Sources of data which have been used
to describe the dispersion potential of the Ukiah District are
discussed in Section 4.3. The discussion then turns to a review
of specific dispersion parameters including prevailing winds,
atmospheric stability, mixing heights, and inversions in Sections
4.4 through 4.6, respectively. More detailed analyses are then
provided, including a review of typical and worst-case conditions
131
for a variety of potential sources in Section 4.7. The air basin
analysis approach to dispersion meteorology is outlined in Sec-
tion 4.8. Section 4.9 provides a discussion of the impact of
dispersion meteorology on burn conditions while section 4.10
describes concepts of air quality modeling including suggestions
as to the manner in which the data presented in thi*s document
should be interfaced with appropriate models. Finally, Section
4.11 provides a review of sources of assistance to BLM personnel
encountering problems in dispersion meteorology while Section
4.12 provides a glossary of terms.
132
4.2
PRINCIPLES OF DISPERSION METEOROLOGY
Dispersion meteorology provides an evaluation of the
capability of the atmosphere to disperse airborne effluents in a
given geographical region. That capability depends largely on
the critical meteorological parameters wind speed and direction,
atmospheric stability and mixing height. The topography of the
region also plays an important role.
The air pollution cycle can be considered to consist of
three phases: the release of air pollutants at the source, the
transport and diffusion in the atmosphere, and the reception of
air pollutants in reduced concentrations by humans, plants,
animals, or inanimate objects. The major influence of meteorolo-
gy occurs during the diffusion and transport phase. The motions
of the atmoshphere which may be highly variable in four dimen-
sions, are responsible for the transport and diffusion of air
pol 1 utants .
Although the distribution of a cloud of pollutant mate-
rial with time will depend on the summation of all motions of all
sizes and periods acting upon the cloud, it is convenient to
first consider some mean atmospheric motions over periods on the
order of an hour.
The following sections discuss (1) the principles of
turbulence and diffusion, (2) the key dispersion parameters, (3)
the role of topography in diffusion and (4) atmospheric chemis-
try. Modeling is discussed in detail in Section 4.9 while in-
strumentation is reviewed in Section 7.
4.2.1
Principles of Turbulence and Diffusion
When a small concentrated puff of gaseous pollutant is
released into the atmosphere, it tends to expand in size due to
the dynamic action of the atmosphere. In so doing, the concen-
tration of the gaseous pollutant is decreased because the same
amount of pollutant is now contained within a larger volume.
This natural process of high concentrations spreading out to
lower concentrations is the process of diffusion.
Atmospheric diffusion is ultimately accomplished by the
wind induced movement of pollutants, but the character of the
source of pollution requires that this action of the wind be
taken into account in different ways. These sources can be
conveniently grouped into three classes: point sources, line
sources, and area sources. In practice, the first two classes
must be further divided into instantaneous and continuous
sources .
The instantaneous point source is essentially a "puff"
of material created or ejected in a relatively short time, as by
a nuclear explosion, the sudden rupture of a chlorine tank, or
133
the bursting of a tear-gas shell. The wind of immediate impor-
tance is, of course, that occurring at the place and time at
which the pollutant is created. Since the wind is highly vari-
able, the initial direction of movement of the puff is also
variable and difficult to predict; a soap-bubble pipe and five
minutes' close observation of the initial travel of "successive
bubbles will convincingly demonstrate the difficulty of predict-
exact trajectory of the next bubble. In addition, dilu-
a puff source is a very strong function of time after its
At first, the small-scale fluctuations of the wind
to grow rather slowly and the larger-scale wind varia-
paths. But as the puff
"hold"
i n g the
t i o n of
rel ease
cause i t
tions simply carry it along on erratic
grows, larger-scale motions can get a
on it to tear it
apart and dilute it more rapidly. Thus, the unique feature of
the instantaneous point source is its increasing dispersion rate
with time, hence, the necessity to consider successively larger
scales of meterorological phenomena in calculating its spread.
Continuous point sources (the smoke plume from a fa
chimney, the pall from a burning dump) are the most familiar
most conspicuous, and the most studied of all pollution sou
The meteorology of the continuous source must take into ac
the time changes of the wind at
behavior of a plume from a factory
of water from a hose being played
It is evident that if the hose is
continually exposed to the water,
back and forth in an arc
uted over a wider area.
the point of emission,
chimney is very much like
back and forth across a
steady, the same area wi
But if the hose ( wi nd )
the water (pollution) will be dis
hence the concentration will be
For a truly continuous source, there are other changes of
importance - primarily the diurnal and seasonal cycles.
ctory
, the
rces .
count
The
that
I a wn .
II be
moves
t r i b -
less,
great
The isolated line source is less common, and therefore,
of less general interest, with two important exceptions - heavily
traveled highways, and the swath of chemicals emitted by crop-
dusting apparatus. In both these examples, if the line of pollu-
tant is uniform and is long enough, the dispersion of the pollu-
tion must be attained in only two dimensions, along the wind and
in the vertical. If the line source is a continuous one, as
might be the case of a freeway in rush hours, spreading in the
downwind direction becomes ineffective (at a particular downwind
location), so that only the vertical dimension is left to provide
dilution. This behavior of the continuous line source has been
exploited by meteorologists in field experiments with controlled
tracers to permit the detailed study of vertical diffusion,
uncomplicated by effects in the other two coordinates.
The area source can \iary enormously in size. It may be
distributed over several square miles, as in an industrial park,
over tens or hundreds of square miles, as in a city, or over
thousands of square miles, exemplified by the almost continuous
strip city (the "megalopolis" or "megapolitan area") along the
eastern seaboard of the United States. These area sources usual-
ly include combinations of all the s i ngl e- source configurations.
134
A large city will include many thousands of home chimneys, thou-
sands of factories and shops, hundreds of miles of streets, open
dumps, burning leaves, evaporating fumes from gasoline storage or
from cleaning plants and paint factories, and everywhere the
automobile. The weather problem of the city area source becomes,
in the aggregate, quite different from that of a single source.
Here we are concerned not with the increasing rate of wind dis-
persion with increasing scale, or with the behavior of wind with
time at a single point, but rather with the replenishment rate of
the air over the city. We must consider the total movement of a
large volume of air as it "ventilates" the city. Anything that
reduces this ventilation rate, whether it be the confining effect
of surrounding mountains or the reduced velocities of a slow-
moving anticyclone, is of concern.
In the construction of cities man has modified the
weather as will be discussed in more detail in Section 4.2.6.
The volume of effluent injected into the air has reduced the
solar radiation. The absorption characteristics of cement and
asphalt instead of grass and trees create urban "heat islands."
These effects must be considered in the meteorology of urban air
pollution. The urban heat island effect is discussed in more
deta i 1 in Sect ion 3.9
The atmosphere disperses pollutants because it is in
constant mostion, and this motion is always turbulent to some
degree. There is, as yet, no fully accepted definition of turbu-
lence, but empirically it can be described as random (three-
dimensional) flow. The understanding of turbulent diffusion in
the atmosphere has progressed largely through empirical treat-
ments of controlled tracer experiments. The current tendency is
to deal with turbulence through statistical concepts derived from
aerodynamics and fluid dynamics, in contrast to earlier theories
which centered around a v i rt ua 1 -d i f f us i v i ty concept. In the
practical application of computing pollution concentrations, the
common practice is to employ the statistical method for distances
to perhaps 150 kilometers (93 miles) from the source, and equa-
tions based on v i rt ua 1 -di f f us i v i ty ("K") theory for longer dis-
tances, particularly for calculations on a hemispheric or global
scale.
Vertical Turbulent Diffusion
To all intents and purposes rapid atmospheric diffusion
in the vertical is always bounded: on the bottom by the surface
of the earth and at the top by the tropopause. The tropopause -
the demarcation between the troposphere, where temperature de-
creases with altitude, and the stratosphere, where the tempera-
ture is relatively constant or increases with altitude - is
lowest over the poles, at about 5 miles, and highest in the
tropics, at about 12 miles. The full depth of the troposphere is
available for vertical dispersion. However, utilization of this
total vertical dimension can take place at very different rates,
depending on the thermally driven vertical wind. These rates are
135
intimately related to the vertical temperature profile. On the
average (and if we neglect the effects of the phase change of
water in the air), enhanced turbulence is as soc i ated wi th a dro
in temperature with height of 10 C per kilometer (29 F per mile
or greater (this is the dry adiabatic rate as discussed in Sec-
tion 4.2.3). If the temperature change with height is at a
lesser rate, turbulence tends to be decreased, and if the temper-
ature increases with height (an "inversion"), turbulence is very
much reduced.
The temperature profiles particularly over land, show a
large diurnal variation as seen in Figure 4.2-1. Shortly after
sunrise, the heating of the land surface by the sun results in
rapid warming of the air near the surface; the reduced density of
this air causes it to rise rapidly. Cooler air from aloft re-
places the rising air "bubble," to be warmed and rise in turn.
This vigorous vertical interchange creates a " super- adi ab at i c"
lapse rate - a temperature decrease of more than 29 F per verti-
cal mile - and vertical displacements are accelerated. The depth
of this well-mixed layer depends on the intensity of solar radia-
tion and the radiation characteristics of the underlying surface.
Over the deserts, this vigorous mixing may extend well above 2
miles, while over forested lake country, the layer may be only
from three to seven hundred feet thick. Obviously, this effect
is highly dependent on season; in winter, the lesser insolation
and unfavorable radiation characteristics of snow cover greatly
inhibit vertical turbulence.
I n contrast ,
temperature profile at
radiational cooling of
the layers of air near the surface,
of the daytime temperature profile,
with clear or partly cloudy skies the
night is drastically changed by the rapid
the ground and the subsequent cooling of
This creates an "inversion"
since there is now an in-
crease in temperature with height. In such a situation the
density differences rapidly dampen out vertical motions, which
tends to reduce vertical turbulence, and stabilize the atmos-
phere .
Two other temperature configurations, on very different
scales, have important effects on vertical turbulence and the
dilution of air pollution. At the smaller end of the scale, the
heat capacity of urban areas and, to a lesser extent, the heat
generated by fuel consumption act to modify the temperature
profile. The effect is most evident at night, when the heat
stored by day in the buildings and streets warms the air and
prevents the formation of the surf ace- based temperature inver-
sions typical of rural areas. Over cities, it is rare to find
inversions in the lowest 300 feet; the city influence is usually
evident 700 to 1000 feet above the surface. The effect is a
function of city size and building density, but not enough obser-
vations are yet available to provide any precise quantitative
relations. Although the effect even for the largest cities is
probably insignificant above three thousand feet, this locally
produced vertical mixing is quite important. Pollution, instead
136
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QJ
S-
Z5
■o
O)
CD
Q.
IS)
■D
C
C
13
CD
S_
-M
03
5-
CD
E
QJ
■r- O
O
It
3
(SH3J.3K 1M0I3M)
137
of being confined to a narrow layer near the height of emission,
perhaps only 300 feet in thickness, can be freely diluted in more
than double the volume of air, the concentrations being reduced
by a similar factor .
On a much larger scale the temperature profile can be
changed over thousands of square miles by the action of large-
scale weather systems. In traveling storm systems (cyclones),
the increased pressure gradients and resulting high winds, to-
gether with the inflow of air into the storm, create relatively
good vertical mixing conditions. On the other hand, the flat
pressure patterns, slower movement, and slow outflow of surface
air in hig h- press ure cells (anticyclones) result in much less
favorable vertical mixing. This is primarily due to the gradual
subsidence of the air aloft as it descends to replace the outflow
at the surface. During this descent, the air warms adiabatical-
ly, and eventually there is created a temperature inversion
aloft, inhibiting the upward mixing of pollution above the inver-
sion level. As the anticyclone matures and persists, this subsi-
dence inversion may lower to very near the ground and persist for
the duration of the particular weather pattern.
Horizontal Turbulent Diffusion
The most important difference between the vertical and
horizontal dimensions of diffusion is that of scale. In the
vertical, rapid diffusion is limited to about 10 kilometers ( 6
miles). But in the horizontal, the entire surface of the globe
is eventually available. Even when the total depth of the tropo-
sphere is considered, the horizontal scale is larger by at least
three orders of magnitude, and the difference, say during a
nocturnal inversion which might restrict the vertical diffusion
to within a hundred feet, is even greater since the lateral
turbulence is reduced less than the vertical component. Mechan-
ically produced horizontal turbulence is, on a percentage basis,
much less important than the thermal effects; its effects are of
about the same order of magnitude as the vertical mechanical
effects .
The thermally produced horizontal turbulence is not so
neatly related to horizontal temperature gradients as vertical
turbulence is to the vertical temperature profile. The hori-
zontal temperature differences create horizontal pressure fields,
which in turn drive the horizontal winds. These are acted upon
by the earth's rotation (the Coriolis effect) and by surface
friction, so that there is not such a thing as a truly steady-
state wind near the surface of the earth. Wind speeds may vary
from nearly zero near the surface at night in an anticyclone, to
200 miles per hour under the driving force of the intense pres-
sure gradient of a hurricane. The importance of thi s *var i at i on ,
even though in air pollution we are concerned with much more
modest ranges, is that for continuous sources the concentration
is inversely proportional to the wind speed.
138
The variation of turbulence in the
perhaps the most important factor of all and
most interesting. In practice, this can be
the changes in horizontal wind direction i
4.2-2. Within a few minutes, the wind m
through 90 degrees or more. Over a few hour
with much short-period variability, through
the course of a month it will have changed
numerous times. Over the seasons, preferred
will be established depending upon latit
pressure patterns. These patterns may be v
years, and thus establish the wind climato
location.
lateral direction is
certainly one of the
st be represented by
llustrated in Figure
dy fluctuate rapidly
s it may shift , still
180 degrees , and i n
through 360 degrees
directional patterns
ude and 1 arge- seal e
ery stable over many
logy of a particular
The emitted pollution travels with this ever-varying
wind. The high-frequency fluctuations spread out the pollutant,
and the relatively steady "average" direction carries it off -
for example, toward a suburb or a business district. A gradual
turning of direction transports material toward new targets and
gives a respite to the previous ones. Every few days the cycle
is repeated, and over the years the prevailing winds can create
semipermanent patterns of pollutions downwind from factories or
cities.
4.2.2
Prevailing Winds
Wind speed and direction play a fundamental role in the
dispersion of airborne contaminants. The following paragraphs
discuss wind speed and direction and other wind characteristics
and their associated impact on local and regional dispersion
potential .
Mean wind direction has a basic impact on air pollutant
levels. If the wind direction is representative of the height at
which the pollutant is released, the mean direction will be
indicative of the direciton of travel of the pollutants. In
meteorology, it is conventional to consider the wind direction as
the direction from which the wind blows, therefore, a northwest
wind will move pollutants to the southeast of the source.
The effect of wind speed is two- fold. The wind speed
will determine the travel time from a source to a given receptor,
e.g., if a receptor is located 1000 meters (3281 ft) downwind
from a source and the wind speed is 5 met ers/ second (16.4
ft/sec), it will take 260 seconds for the pollutants to travel
from the source to the receptor. The other effect of wind speed
is- a dilution in the downwind direction. If a continuous source
is emitting a certain pollutant at the rate of 10 grams/second
( 1.3 lbs/min) and the wind speed is 1 meter/second ( 2.2 mph)
then in a downwind length of the plume of 1 meter (3.3 feet) will
be contained 10 grams ( 0.02 lbs) of pollutant since 1 meter (3.3
feet) of air moves past the source each second. Next, consider
that the conditions of emission are the same but the wind speed
is 5 met ers/ second ( 11 mph). In this case, since 5 meters (16.4
139
?i§m
E
O
•n-
+->
fD
u
oo
•r—
1
M-
CXI
•!—
•
CO
«*
CO
(C
<u
r^
s-
o
3
en
CO
■^~
CO
u_
CD
c
• ^
+->
CO
CD
140
feet) of air moves past the source each second, each meter of
plume length contains 2 grams ( 0.04 lbs) of pollutant. There-
fore, it can be seen that the dilution of air pollutants released
form a source is proportional to the wind speed. This may be
restated in another form: The concentration of air pollutants is
inversely proportional to wind speed.
Wind speed is generally found to increase with height
above the ground and wind direction to veer (turn clockwise) with
height (in the northern hemisphere at extratropical latitudes)
due to the effects of friction with the earth's surface. The
amount of these increases in speed and veering in direction are
quite variable, and to a great degree, related to the roughness
of the surface and the stability of the atmosphere.
mean
are
i n a
ones
ods
poll
call
seal
than
will
the
This
even
orde
act i
In the preceding paragraphs, consideration of only the
speed and direction of wind has been made. Of course, there
deviations from these means. There are velocity components
11 directions creating vertical motions as well as horizontal
These random motions of widely different scales and peri-
are essentially responsible for the movement and diffusion of
utants about the mean downwind path. These motions, commonly
ed eddys, are considered as atmospheric turbulence. If the
e of a turbulent motion, i.e., the size of an eddy, is larger
the size of the pollutant plume in its vicinity, the eddy
portion of the plume. If an eddy is smaller than
effect will be to diffuse or spread out the plume,
caused by the eddy motion is widely variable, but
duffusion is at the minimum, it is roughly three
rs ot magnitude greater than the diffusion by molecular
on
move that
pi ume , its
diffusion
when this
of magni t ude
alone.
During the daytime, solar heating causes turbulence to
be at a maximum and vertical motions to be strongest. This
causes the maximum amount of momentum exchange between various
levels in the atmosphere. Because of this, the variation of wind
speed with height is least during the daytime. Also, the amount
of veering with height is least (on the order of 15 to 20 over
average terrain). The thickness of the friction layer will also
be greatest during the day due to the vertical exchange.
At night, the vertical motions are least and the effect
of friction is not felt through as deep a layer as during the
day. The surface speed over average terrain is much less than
the free atmosphere wind (on the order of 1/4 to 1/3 that of the
1000 meter (3281 feet) wind) and the amount of veering with
he-ight may be on the order of 40 to 45 . Figure 4.2-3 shows the
diurnal variation of wind speed at two different levels on a
meteorological tower (Singer and Raynor, 1957).
Wind data are generally only available in terms of speed
and direction. Turbulence data are considerably more sophisti-
cated and are generally only available as a result of special-
ized, si te- speci f i c data gathering programs. Such data are only
141
WIND
SPIED
(M/SEC,
10
9
e
7
6
5
4
3
?
1
0
410 FEET
37 FEET
-L
1
-L
J_
J.
SUNPISE
MIDDAY SUNSET MIDNIGHT SUNRISE
Figure 4.2-3
Diurnal Variations in Wind Speed
As a Function of Height
{*■' Data from Meteorological Tower
Brookhaven National Laboratory
April 1950-March 1952
142
wind direction.
wh i c h eight or
The 1 ength of
wind from that
used in very detailed modeling analyses. The bulk of the model-
ing analyses conducted for the air pollution industry require
only basic wind data for speed and direction. This latter type
of data are generally summarized in the form of wind roses.
These may be viewed in Figure 4.4-1.
A wind rose is defined in the Glossary of Meteorology
as, "Any one of a class of diagrams designed to show the distri-
bution of wind direction experienced at a given location over a
considerable period; it thus shows the prevailing
The most common form consists of a circle from
sixteen lines emanate, one for each compass point
each line is proportional to the frequency of
direction; and the frequency of calm conditions is entered in the
center. Many variations exist. Some indicate the range of wind
speeds from each direction; some relate wind direction with other
weather occurrences." Wind roses may be constructed for data
from a given time period such as a particular month or may be for
a particular time of day or season from a number of years of
data. In constructing or interpreting wind roses, it is neces-
sary to keep in mind the meteorological convention that wind
direction refers to the direction from which the wind is blowing.
A line or bar extending to the north on a wind rose indicates the
frequency of winds blowing from the north, not the frequency of
winds blowing towa rd the north. Some of the specialized wind
roses that may be constructed are precipitation wind roses,
stability wind roses, and pollution wind roses. The latter two
require additional data than are generally available at standard
Weather Bureau stations. An informative article on the history
and variants of wind roses has been published by Court (1963).
Prior to January 1964, the surface wind direction was
reported by U.S. Weather Bureau stations as one of the 16 direc-
tional points corresponding to the mariner's compass card or
compass rose, qn which each direciton is equivalent to a 22 1/2
sector of a 360 circle. Table 4.2-1 illustrates, in the form of
a frequency table of wind direction versus wind speed groups, the
data essential to the development of a 16-point wind rose. It is
an example of summaries of hourly observations published monthly
until January 1964 in the Local Climatological Data (LCD) Supple-
ment. Frequencies are totaled by direction and wind speed group.
A quick look at this wind rose indicates the highest directional
frequency is from the ENE and the highest speed frequency is the
8 to 12 mph column. Average speeds have been computed for each
direction.
When wind roses are employed to summarize climatological
data involving long periods of record, percentage frequencies are
favored over numerical totals for tabular presentation since the
number of observations in any one cell can become quite large.
Moreover, wind rose diagrams can be drafted directly from tabular
data if percentages are available. Table 4.2-2 presents 10 years
of hourly wind data observed at New Orleans Moisant International
143
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Airport during January for the years 1951 through 1960, as pub-
lished in the "Decennial Census of United States Climate." This
10-year summary of meteorological data is compiled for most U.S.
Weather Bureau first order stations.
On January 1, 1964, the U.S. Weather Bureau Changed the
wind direction reporting procedure from 16 points to 36 - 10°
intervals. Table 4.2-3 is the result; a 3 6-point wind rose.
Since 36 cannot be divided by 16 there is no way of grouping 36
points into 16 points and there is no easy way of combining wind
data if the wind rose summaries include both 16-point and 36-
point wind direction observations. For this and other reasons,
the 36-point wind rose was dropped after 1964. A few air quality
models such as CRSTER require 36 point wind rose data, and for
such an application, 1964 data must be used.
This report will present wind roses using a very sim-
plistic format. The frequency of the wind direction for each of
the 16 cardinal directions is plotted and lines are drawn connec-
ting each directional frequency (See Section 4.4.1)
4.2.3
Atmospheric Stability
Whether the atmosphere has a tendency to enhance or to
dampen out vertical motions is important to atmospheric processes
which produce weather as well as to the effects upon air pollut-
ant dispersion. The stability of the atmosphere is highly de-
pendent upon the vertical distribution of temperature with
height .
Adiabatic Lapse Rate
Due to the decrease of pressure with height, a parcel of
air lifted to higher altitude will encounter decreased pressure
and expand and, in undergoing this expansion, will cool. If this
expansion takes place without loss or gain of heat to the parcel,
the change is adiabatic. Similarly, a parcel of air forced
downward in the atmosphere, will encounter higher pressures,
contract, and become warmer. This rate of cooling with lifting,
or heatina with descent is the dry adiabatic lapse rate and
equals 5.4 F per 1000 feet or approximately 1°C per 100 meters.
This process lapse rate is the rate of heating or cooling of any
descending or rising parcel of air in the atmosphere and should
not be confused with the existing temperature variation with
height at any one time, i.e., the environmental lapse rate.
Environmental or Prevailing Lapse Rate
The manner in which temperature changes with height at
any one time is the environmental or prevailing lapse pate. This
is principally a function of the temperature of the air and of
the surface over which it is moving and the rate of exchange of
For example, during clear days in mid-
heat between the two.
summer the ground is rapidly heated by solar radiation. This in
turn, provides for rapid heating of the layers of the atmoshpere
146
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147
nearest the surface. Further aloft, however, the atmospheric
temperature will remain relatively unchanged. Conversely, at
night, radiation from the earth's surface cools the ground and
the air adjacent to it, resulting in only slight decrease of
temperature with height, and in cases when the surface cooling is
great enough, temperature may increase with height. "Hi i s atmos-
phere is considered stable.
If
If the temperature decreases
than the dry adiabatic lapse rate, the
or strong lapse rate and the air is unstable .
is forced upwards it will cool at the adiabatic
will still be warmer than the environmental air
continue to rise. Similarly, a parcel which is
will heat dry ad i abat i cal 1 y but will remain
environment and will continue to sink.
more rapidly with height
air has a su pe r- ad i abat i c
a parcel of air
1 apse rate , but
Thus it will
forced downward
cool er than the
For environmental lapse rates that decrease with height
at a rate less than the dry adiabatic lapse ( sub- adi abat i c or
weak lapse) a lifted parcel will be cooler than the environment
and will sink; likewise, a descending parcel will be warmer than
the environment and will rise. Figure 4.2-4 shows the relative
relation between the environmental lapse rates of super- adi abat i c
(strong lapse), sub-ad iabatic (weak lapse), isothermal, and
inversion with the dry adiabatic process lapse rate presented as
dashed lines.
Lifting motions which promote cooling at dry adiabatic
lapse rates may be caused by upslope motion over mountains or
warmer air rising over a colder air masses. Descending motion
(subsidence) may occur to compensate for the lateral spreading of
air in high pressure areas.
Classification Schemes
The dispersive power of the atmosphere can be cate-
gorized into seven classes, labeled stability categories, in
accordance with a method proposed by Pasquill (1962) and modified
by Gifford (1961) and Markee (1966). Pasqu ill's first three
classes, A, B, and C, range from extreme to slight instability.
Class D represents neutral or well-mixed conditions, while E and
F represent slight and moderate stability, respectively. Disper-
sive power decreases with progression through these classes.
Markee (1966) has further divided the original class F into
classes F and G, with G representing extreme stability. For the
purpose of simplifying the presentation, classes A, B, and C have
be-en combined, in some instances, to form one category called
unstable. Similarly, class D will be referred to as the neutral
category, and classes E, F, and G together form the stable cate-
gory.
The stability of the atmosphere is determined by various
methods using numerous forms of meteorological data. A frequent-
ly used means of assessing ambient atmospheric stability is
148
V
\
\
SUPER-
■ADIABAT1C
\
v\
\
\
\x
\
\
\
\
\
\
^ \ SUB-ADIABATIC
\ \
\ v
\
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\
\
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\
\
ISOTHERMAL
\
\ \
\
\
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—
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\
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\
\
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\
\
\ /
\
\
/\
INVERSION
\
TEMPERATURE
Figure 4.2-4
Types of Temperature Structure with Height Related to
the Dry Adiabatic Process Lapse Rate
149
through the measurement of changes in atmospheric temperature
with altitude ( T/ Z) above an area in question. This is accom-
plished by probing the atmosphere with specialized temperature
sensors mounted on aircraft, balloons, or on tall meteorological
towers .
Figure 4.2-5 graphically illustrates the T/ Z criteria
for stable, neutral and unstable conditions. Temperature profile
"A" is classified as unstable because its profile slope is less
than the dry adiabatic lapse rate ( T/ Z = -9.8°C/km) (-28.4°
F/mi). A neutral atmosphere is one that exhibits a temperature
profile approximately equivalent to the dry adiabatic lapse rate.
Stable atmospheres have T/ Z values greater than -9.8 C/km
(-28.4 F/mi). An atmospheric inversion, a special case of a
stable atmosphere, occurs when the ambient T/ Z value increases
with altitude rather than decreases.
Unstable conditions generally occur during periods of
high positive net radiation (toward the earth's surface) and low
wind speeds. Stable conditions require high negative net radia-
tion (away from the earth's surface) and low wind speeds, while
neutral conditions generally develop because of cloudy skies
and/or high winds speeds. This more general method of defining
atmospheric stability is the one most frequently used in the air
pollution industry today.
The NCC in Asheville, North Carolina, has devised a
somewhat subjective technique based upon available measurements
of surface wind speed coupled with the strength of incoming solar
insolation as defined by such parameters as sky cover, time of
day and latitude. This technique is summarized in Table 4.2-4
and is used by the NCC to develop the STAR (Stability A_R_ay) data
that is used extensively in this document. One interesting
aspect of this technique results from the heavy dependance upon
solar insolation. By this definition, stable conditions can
occur only at night, unstable conditions only during the day,
while neutral conditions can occur during either night or day.
The Influence Of Vertical Temperature Structure Upon Plume
Behavior
The manner in which stack effluents diffuse is primarily
a function of the stability of the atmosphere. Church (1949) has
typified the behavior of smoke plumes into five classes. Hewson
(1960) has added a sixth class, taking into account inversions
aloft (Inversions will be discussed in more detail in section
4 . -2 . 4 ) . Figure 4.2-6 depicts each class and the appropriate
dispersion characteristics for an idealized chimney. The Pas-
quill stability classes are also noted.
Looping
Looping occurs with a super- ad i abat i c lapse rate. Large
thermal eddies are developed in the unstable air and high concen-
trations may be brought to the ground for short time intervals.
150
1.0
E
LU
a 0.5
10
15
20
25
T(°C)
Figure 4.2-5
Temperature Profiles which are Examples of
(A) Unstable, (B) Stable, and (C) Very Stable Inversion
Lapse Rates in a Dry Atmosphere
151
Table 4.2-4
Key to Stability Categories
Surface Wind
Speed (at 10 m)
m/sec
Isolation
Slight
Night
< 3/8
Cloud
Thinly Overcast
or
> 4/8 Low Cloud
Strong
Moderate
< 2
A
A-B
B
-
-
2-3
A-B
B
C
E
F
3-5
B
B-C
c
D
E
5-6
C
C-D
D
D
D
> 6
C
D
D
D
D
The neutral category, D, should be assumed for overcast conditions during
day or night.
152
Stability Category A-C; Looping
Stability Category D; Coning
Stability Category E-G; Fanning
T
BK i. —> ■ ' . ■ .1 ■ <-tf
Stability Categories As Noted,
Lofting
J L
E-G
Stability Categories As Noted;
Fumigation
E-G
Figure 4.2-6
i
Typical Plume Behavior
Stability Categories As Noted;
Trapping Inversion
E-G
A-D
Plume behavior influenced by the temperature lapse rate above and below the
release height. The dashed lines in the profiles are the adiabatic lapse
rates, included for reference, while the solid lines indicate the actual
lapse rate. The Pasquill stability categories are also provided.
153
Diffusion is good, however, when considering longer time periods.
The super-ad iabatic conditions which cause looping occur only
with light winds and strong solar heating. Cloudiness or high
winds will prevent such unstable conditions from forming.
Coning
With vertical temperature gradients between dry adia-
batic and isothermal, slight instability occurs with both hori-
zontal and vertical mixing but not as intense as in the looping
situation. The plume tends to be cone shaped hence the name
coning. The plume reaches the ground at greater distances from
the source than with the looping plume. Coning is prevalent on
cloudy or windy days or nights. Diffusion equations are more
successful in calculating concentrations for this type of plume
than for any other.
Fanning
If the temperature increases upward as in an inversion,
the air is stable and vertical turbulence is suppressed. Hori-
zontal mixing is not as great as in coning but still occurs. The
plume will, therefore, spread horizontally but little if any
vertically. Since the winds are usually light, the plume will
also meander in the horizontal. Plume concentrations are high
but, little effluent from elevated sources reaches the ground,
except when the inversion is broken due to surface heating, or
terrain effects at the elevation of the plume. Clear skies with
light winds during the night are favorable conditions for
f anni ng .
Lof t i ng
Lofting occurs when there is a super- adi abati c layer
above a surface inversion. With this condition, diffusion upward
is rapid, but downward, diffusion does not penetrate the inver-
sion and so is dampened out. Under these conditions, gases will
not reach the surface but particles with appreciable settling
velocities will drop through the inversion. Near sunset on a
clear evening in open country is most favorable time for lofting.
Lofting is generally a transition situation and, as the inversion
deepens, is replaced by fanning.
F umi gat i on
As solar heating increases, the lower layers are heated
and a super-ad iabatic lapse rate occurs through a continuously
deeper layer. When the layer is deep enough to reach the fanning
plume, thermal turbulence will bring high concentrations to the
ground along the full length of the plume. This is -favored by
clear skies and light winds and is apt to occur more frequently
in summer due to increased heating.
154
Another type of fumigation may occur in the early even-
ing over cities. Heat sources and mechanical turbulence due to
surface roughness causes an adiabatic condition to develop in the
lower layers of the stable air moving into the city from non-
urban areas where radiation inversions are already forming. This
causes a fumigation until the city loses enough heat so that the
adiabatic condition is dim i shed.
Trapp i ng
When an inversion occurs aloft, such as a frontal or
subsidence inversion, a plume released beneath the inversion will
be trapped beneath it. Even if the diffusion is good beneath the
inversion, such as with a coning plume, the limit to upward
diffusion will increase concentrations in the plume and at ground
1 evel .
4.2.4
Mixing Heights and Inversions
An adiabatic diagram can be used to plot the distribu-
tion of temperature and moisture, with height in the atmosphere.
This is of considerable use to the meteorologist in determining
freezing levels, condensation levels of moisture in lifted air
parcels, forecasting cloud bases and tops, determining stability
for cloud formation and thunderstorm forecasting. Moisture
levels are especially important to the air pollution meteorolo-
gist as moisture works as a catalyst for the formation of secon-
dary pollutants such as sulfates and nitrates and high moisture
content will serve to reduce visibility.
To the air pollution meteorologist a sounding plotted on
an adiabatic chart is principally used to determine the large
scale stability of the atmosphere over a given location. The
principal source of atmospheric measurements that may be plotted
on the adiabatic chart are the radiosonde measurements taken
twice daily: 0000 GMT (1900 EST) and 1200 GMT (0700 EST) at about
66 stations in the contiguous United States. The method of
obtaining these soundings is to release into the atmosphere a
balloon borne instrument package having sensors for temperature,
pressure, and humidity and a radio transmitter for relaying this
information to the ground station. This information on the upper
air is collected primarily to serve the purpose of forecasting
and aviation briefing. Consequently, the information is not as
detailed in the lowest 5000 feet as an air pollution meteorolo-
gist desires. Also, in air pollution meteorology, it is desira-
ble to have information more frequently than 12 hours apart. In
spite of these deficiencies for air pollution purposes, the
soundings from the radiosonde network will give indications of
the stability of the atmosphere. On an adiabatic chart, tempera-
ture is plotted on a linear scale against pressure on a logarith-
mic scale. A temperature sounding may be plotted by locating
each significant level reported by the temperature and pressure
given for that level. The plotted points may then be connected
by straight lines to give the temperature sounding.
155
As indicated in Section 4.2.3, the stability of a por-
tion of the sounding may be compared with the dry adiabatic lapse
rate. If the temperature decreases more rapidly than the dry
adiabats through a layer, this layer is super-adiabatic and quite
unstable. If the temperature decreases, but at a rate* less than
the dry adiabatic lapse rate, the layer is sub- ad i abat i c and is
more stable than super-adiabatic. If the temperature increases
with height, it is an inversion.
Inversions with bases at ground level are generally
radiation inversions caused by the cooling of the earth's surface
and the adjacent air. However, there may also be advection
inversions formed by the air's passage over a relatively cold
surface. These two types of surface based inversions generally
cannot be distinguished by inspection of the sounding plotted on
an adiabatic diagram. A surface based inversion on an afternoon
sounding is more apt to be an advection inversion.
There are two general classifications of inversions with
bases above the ground: frontal inversions and subsidence inver-
sions. Both of these, however, can also be ground based.
Frontal inversions are discontinuities in the tempera-
ture profile due to the transition between cold air below and
warm air aloft. Frontal inversions usually are accompanied by
increases in moisture through the inversion. Subsidence inver-
sions are caused by the sinking motion above high pressure areas
and generally have rapidly decreasing humidities above the base
of the inversion.
Surveys of the meteorological aspects of air pollution
are often concerned with the extent of horizontal and vertical
mixing. A quantity referred to as the mixing depth is quite
useful when considering dilution of pollutants in the vertical.
The usual method of estimating mixing depths is to consider the
stability as portrayed on a temperature sounding remembering that
unstable lapse rates favor vertical mixing and stable lapse rates
restrict vertical motion. The mixing depth is generally the
height above the ground to which a super or dry-adi abat i c lapse
rate is maintained as depicted in Figure 4.2-7.
4.2.5
Influence of Topography on Transport and Diffusion
In many cases, the transport and diffusion of air pollu-
tants is complicated by terrain features. Most large urban areas
are located either in river valleys or on the shores of lakes or
oceans. Both of these features alter meteorological conditions.
Val ley Effects
t Channeling
Although the more extreme effects of a valley location
occur when the general flow is light, valleys tend to
156
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157
channel the general flow along the valley axis resulting
in a bi-directional wind frequency distribution.
Slope and Valley Winds
When the general wind flow is light and skies are clear,
the differences in rates of heating and cooling of
various portions of the valley floor and sides cause
slight density and pressure differences resulting in
small circulations. During the evening hours radia-
tional heat from the earth's surface and the resultant
cooling of the ground and air adjacent to the ground
causes density changes. The air at point A (Figure
4.2-8) is more dense than at point B since point A is
nearer the radiating surface. Therefore, the more dense
air at point A tends to flow in the general direction of
B and similarly at other points along the slope. This
i s the si ope wi nd .
If the slope in Figure 4.2-8 is a side of a valley as in
Figure 4.2-9, the cold air moving down the slopes will
tend to drain into the valley floor and deepen with
time, intensifying the radiation inversion that would
form even without the addition of cold air. Any pollu-
tants that are emitted into this air, because of the
inversion structure, will have very limited vertical
mot i on .
If, in addition, the valley floor has some slope, the
cold air will have a tendency to move downhill along the
valley axis. This is usually referred to as the valley
wind (See Figure 4.2-10). Because of the necessity of
some accumulation of cold air from slope winds, the
onset of the valley wind usually lags several hours
behind the onset of the slope wind.
The steeper the slopes of the valley, the stronger the
slope wind can become. Vegetation will tend to reduce
the effect by impeding the flow and also restricting the
amount of radiation that can take place.
On a clear day with the light winds, the heating of the
valley may cause upslope and upvalley winds. However,
the occurance of upslope and upvalley winds is not as
frequent nor as strong as the downslope and downvalley
winds, principally due to the fact that downslope and
downvalley winds, because of their density, hug the
surfaces over which they travel. Flow in complex valley
systems where several valleys merge at angles or slopes
varies, usually require special observations to deter-
mine flow under various meteorologic conditions.
Inversions A 1 oft
The trapping of air pollutants beneath inversions aloft
is also a problem encountered in valleys. Two types of
158
Figure 4.2-8
COLO All
Figure 4.2-9
Figure 4.2-10
Valley Wind Circulations
159
inversions: warm frontal and subsidence inversions are
of particular concern since they are usually slow mov-
ing. High concentrations may occur particularly if the
layer of air beneath the inversion becomes unstable
enough to mix pollutants from elevated sources to ground
level (Hewson et al , 1961).
Shoreline Winds
The differences in heating and cooling of land and water
surfaces and the air above them, result in the setting up of
circulations if the general flow is light, and in the modifi-
cation of thermal characteristics, and consequently, the diffu-
sive abilities of the lower layers of the atmosphere when a
general flow occurs.
• Sea or Lake B reeze
On summer days with clear skies and light winds, the
heating of the land surface adjacent to a large lake or
the ocean is much more rapid than the heating of the
body of water. This results in a temperature differ-
ence, and consequently, a density and pressure differ-
ence between the air just above the land surface and the
air over the water. Because of the pressure gradient
forces, a local circulation is set up with wind from the
water toward the land, There is usually some upward
motion over the land and subsidence over the water
accompanying the sea breeze (Estoque, 1961). There may
result a weak transport from land to water aloft com-
pleting a cellular structure (See Figure 4.2-11).
In cases where a strong lake breeze occurs, air from
quite some distance out over the water may be brought
toward the land and, due to Coriolis forces acting over
the long trajectory, the resulting flow will become
nearly parallel to the shoreline (Sutton, 1953). This
occurs just after the sea breeze is strongest and re-
sults in decreasing the flow normal to the coastline and
the subsequent breakdown of the sea breeze.
• Land Breeze
At night, the rapid radiational cooling of the land
causes lower temperatures above the land surface than
over the water. Thus a reverse flow, the land breeze,
may result. The land breeze does not usually achieve as
high a velocity as the lake breeze, and is usually
shallower than the sea or lake breeze.
Of course, any wind flow, because of the large scale
pressure pattern, will alter the local circulation and
the flow will be the resultant of the two effects.
Usually, a light general flow is enough to overshadow
the effects of land and sea breezes.
160
\\\\\\\\\
LAND
WATER
Figure 4.2-11
Idealized Sea Breeze Regime
161
Modi f i cat i on of Thermal Structure by Bodies of Water
At different seasons of the year and also different
times of the day, the temperature of bodies of water and adjacent
land surfaces may be quite different. For example, during the
late spring, large bodies of water are still quite cofd relative
to adjacent land surfaces, and during mid- afternoon this differ-
ence is greatest due to the more rapid heating of the land sur-
face. If the general flow in the area is such that the wind has
a lengthly trajectory over the water and is blowing toward the
shore, an interesting modification of the temperature structure
takes place. Because of the passage over the cold water surface,
the air will have an inversion in the lower layer as it reaches
the shoreline. Any air pollutants released
will essentially have the characteristics of
the air passes over the warm land, a strong
the inversion near the surface. The depth
deepen as the air moves over more heated land surface. If the
layer becomes deep enough to reach the fanning effluent from an
elevated source, fumigation will occur and continue as long as
the temperature difference between land and water is maintained
and flow from water to land occurs. At greater distances from
the shoreline, the inversion will be eliminated and plume looping
will occur. On the other hand, if the source is high enough to
be above the lake induced inversion, lofting of the plume would
occur until enough distance, and consequently, enough heating
takes place to eliminate the inversion.
into this inversion
a f anni ng pi ume . As
lapse rate repl aces
of this 1 ayer wi 1 1
Figure 4.2-12 indicates the difference in vertical
temperature structure that occurs in the above example, and
Figure 4.2-13 indicates the effect this will have on the plume
characteristics of an elevated shoreline source.
At other times when the water is warmer than the land
surface (late fall), offshore flow will result in fumigation over
the water.
Influence of Hills
The influence of hills upon transport and diffusion
depends upon a number of factors. Whether the source is on the
windward or lee side of the hill or ridge is important. A smooth
hill will only slightly alter the flow, while one with sharp
ridges will cause turbulent eddies to form. The stability of the
atmosphere will affect the overall influence of hills. During
stable conditions, the air will tend to flow around obstructions.
Under unstable conditions, the tendency is for air to move over
obstructions.
When a source is located upwind of a hill orcridge, the
pollutants may come in contact with the facing slope, particu-
larly under stable conditions. If the ridge is quite rough,
induced turbulence may cause mixing down to the slope even when
the general flow is over the ridge. Wind tunnel studies or field
162
GENERAL
WINDFLOW
^'2»
WARM LAND
Figure 4.2-12
Modification of Vertical Temperature Structure Due to Flow
Over Differently Heated Surfaces
GENERAL
WINDFLOW
Pc?£v&
WARM LAND
Figure 4.2-13
Effect Upon Plume Characteristics of Flow Over Differently
Heated Surfaces
163
trials with constant level balloons may be desirable to determine
the flow under given circumstances.
For a source downwind form a hill or ridge, lee eddies
will generally cause considerable down wash of the effleunt near
the source. If turbulent flow is induced by the hillsrde, diffu-
sion will be increased but high concentrations very near the
stack will result periodically, due to the downwash. Examples
may be viewed in Figure 4.2-14
Persistence of Fog
The occurence of fog, together with very stable atmos-
pheric conditions above the earth's surface, has been noted in
several air pollution episodes, particularly in Donora, Pennsyl-
vania, in 1948. Under clear skies at night, the ground loses
much heat because of outgoing radiation and the air in contact
with the ground will cool. If, in such cases the air is suffi-
ciently humid, cooling will bring the air to the saturation point
and a fog will form. This is the mechanism which produces radia-
tion fog and is quite common in valley locations. The top of a
layer of fog will radiate essentially as a black body and cool
further, thus forming an inversion layer directly above the fog.
As the earth continues to radiate in the infrared, the fog drop-
this heat since the droplet size distribu-
wavelengths of the radiation. Theory and
that when the top of a fog layer radiates
interior of the layer will become more
Increased vertical mixing will occur from
below but will be capped by the inversion. Since the air is
saturated, an unstable lapse rate will exist if the temperature
decrease with height is greater than the moist or pseudo-adia-
batic lapse rate (3 F per 1000 ft.), rather than the dry adia-
batic lapse rate of (5.4°F per 1000 ft.)
lets absorb nearly all
tion is similar to the
observation have shown
during the night, the
unstable with time.
Thus, pollutants that are emitted aloft into an orig-
inally stable layer at night, and would not normally reach the
ground until morning, may be contained within a fog layer as the
night progresses and be brought to the ground in relatively high
concentrations.
After daybreak, fog will often persist for several hours
or even the entire day under full sunlight due to the high re-
flectivity of the top layer. The reflectivity or albedo of thick
fogs averages 50% and can be as high as 85%. This delays and
lessens the heating of the ground and subsequent evaporation of
the fog droplets. An unstable lapse rate may occur above the fog
layer, but due to a lack of surface heating, an inversion will
often occur within the layer. If high concentrations of particu-
late pollutants are present, it
just when the fog has dissipated
absorb visible light very well
quite restricted.
may be difficult to* determine
since particulates scatter and
and the visibility may remain
164
Figure 4.2-14
Influence of Hills Upon Transport and Diffusion
165
Figure 4.2-15 illustrates how fog can persist in valley
situations and maintain a lid on vertical dispersion. This
situation often occurs over the Central Valley of California
during winter. The conditions, known locally as "Tule Fog" can
persist for days resulting in reduced visibilities and poor
ambient air quality.
166
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167
4.3
DATA SOURCES
A limited number of sources of dispersion meteorological
data are available in the Ukiah District. Some of these data are
available in unreduced or partially reduced form and have not
been utilized in the present analysis. However, a knowledge of
their availability is desirable in instances where they may be of
value for future more detailed site-specific analyses.
For the present, the data base has been limited to
sources of data readily available, reduced, and in summarized
form which cover a period of 5 years or more. As discussed
earlier, key parameters of interest include wind speed and wind
direction, atmospheric stability, mixing heights, temperature
inversions, and winds aloft. Primary sources of such complete
data include first order National Weather Service (NWS) stations
and special interest (usually private industry) stations. Figure
4.3-1 provides an illustration of the locations of key meteorolo-
gical stations located in the Ukiah District which have been used
to establish a regional assessment of dispersion meteorology.
Other reference materials and data sources are also discussed in
the text in instances where they add additional insight into the
dispersion meteorology for specific areas.
The following sections are based upon three key sets of
data. These include (1) STability ARray (STAR) data as available
from the National Climatic Center (NCC) in Asheville, North
Carolina and (2) NWS and California Air Resources Board (CARB)
upper air temperature and wind data. STAR data provide the joint
frequency distribution of wind speed, wind direction and atmos-
pheric stability class on a monthly, seasonal and annual basis.
Within the Ukiah District, STAR data for Areata and Ukiah have
been used in the more exhaustive analyses. STAR data are
available for other stations in the district as indicated on the
study map. The data used in this report were chosen to provide a
representative and cost-effective cros s- sect i on of the dispersion
meteorology of the District. Table 4.3-1 provides a summary of
the available dispersion meteorological data from NWS and CARB
sources in the Ukiah District. All of these data have been
utilized in the present analysis as appropriate.
168
ELK VALLEY
SMITH RIVER
CRESCENT CITY
DEL NORTE
KLAMATH
1
I
ORICK
HUMBOLDT
HOOPA .
ARCATA
BLUE LAKE
KORBEL
A
• KNEELAND
^^Eudfx
. FORTUNA
TIA • . BRIDGEVILLE
ALDERPOINT
• GARBERVILLE,
, CUMMINGS
• COVELO
BRANSCOMB
TYPES OF DATA
* STAR DATA
▲ UPPER AIR DATA
20
L_
20
MILES
DELEVAN
• POTTER VALLEY
MENDOCINO 1 ^N
• CALPELLA " "•»
^1
MAXWELL
UKIAH
**[A LAKE
WILLIAMS*
I m. LAKE I
y • LAKEPORT ^
• HOPLAND . CLEARLAKE HIGHLANDS
• CLOVERDALE f \
ANNAPOLIS * / \
HEALDSBURG »-"" *""
40
_L_
60
-J
W.SACRAMENTO
SONOMA
. SANTA ROSA
OCCIDENTAL \
BODEGA \
N
\
MARIN
SAN RAFAEL
Figure 4.3-1
Sources of Dispersion Meteorological Data
Used in the Ukiah District Analysis
169
Table 4.3-1
Available Dispersion Meteorological Data
in the Ukiah District
Period of
Station Name
County Location
Data Description
Data Base
Areata
Humboldt
Wind speed, wind direction
and atmospheric stability
(24 obs./day)
1/68-12/72
Ukiah
Mendocino
Wind speed, wind direction
and atmospheric stability
(24 obs./day)
1/55-12/64
Fairfield
Travis AFB
Wind speed, wind direction
1/60-12/64
Solano
and atmospheric stability
(24 obs./day)
San Rafael
Hamilton AFB
Wind speed, wind direction
1/60-12/64
Marin
and atmospheric stability
(24 obs./day)
1/66-12/70
Ukiah
Mendocino
Vertical temperature
sounding and mixing
height summaries
ongoing
Areata
Humboldt
Vertical temperature
soundings
4/45-9/45
Eureka
Humboldt
Vertical temperature
soundings
10/71-11/71
170
Upper air wind and temperature data are also available
for certain portions of the Ukiah District. There are no first
order stations routinely taking temperature and winds aloft data
in the district. Nearby data from Oakland have been utilized by
Holzworth (1972) to provide data on inversion types and
frequencies, as well as mixing heights and mean w4nd speeds
through the mixing layer. The CARB has also conducted various
programs for the collection and summarization of temperature
sounding and/or pilot balloon (winds aloft) release data at
selected stations throughout the state. In the Ukiah District,
this includes Ukiah. The availability of these data permits
finer resolution of mixing heights and inversions in the
district. The available NWS data would be insufficient to
clearly describe these parameters in the Ukiah District.
171
4.4
PREVAILING WINDS
The characterization of prevailing surface winds and
winds aloft is essential in the development of an understanding
of the dispersion meteorology of the Ukiah District. This sec-
tion provides analyses that are designed to identify specific
characteristics of the prevailing winds. These analyses include:
Wind Roses
Diurnal Wind Distributions
Wind Speed Distributions
Wind Persistence Analyses
Trajectory Analyses
Winds Aloft
The prevailing winds define the net regional transport character-
istics for pollutants in a given geographical area. An under-
standing of the physical behavior of air flow in and out of a
particular area of interest provides insight as to the fate of
air pollutants.
4.4.1
Wind Roses
Wind roses provide a graphical representation of the
frequency of occurrence of winds from each of the 16 cardinal
directions for specified averaging periods. This subsection
discusses the prevailing winds using wind rose analyses on a
seasonal and annual basis.
Regional wind characteristics throughout the Ukiah
District are discussed in considerable detail in Section 3.4.
This includes a summary of monthly and annual average wind speeds
and prevailing wind directions throughout the study area. Also,
a Ukiah District study map with numerous superimposed annual wind
roses was provided in order to depict the air flow on a regional
scale. The discussion provided in this section is designed to
summarize prevailing air flow characteristics in terms of a
dispersion analyses for subsequent use in pollutant impact
st udi es .
Annual
Annual wind rose diagrams for selected key stations in
the district are provided in Figures 4.4-1 through 4.4-4. Areata
and San Francisco wind roses describe wind conditions character-
istic of coastal areas. Ukiah represents a typical inland valley
station while Sacramento represents a Central Valley station.
Figure 4.4-5 provides a study map of the district, superimposed
with several annual wind rose diagrams. This figure appeared in
Section 3.4 but is presented here, as well, due to its importance
in describing regional flow characteristics.
172
FREQUENCY OF OCCURRENCE (%)
ANNUAL WIND ROSE
SITE:
ARCATA
bl
wni/ / /CI \1^
\NNE
\^0 /
ssw ^"""
5 ' " SSE
PERIOD
YEARS 1968-1972
Figure 4.4-1
Annual Wind Rose for Areata
173
FREQUENCY OF OCCURRENCE {%)
ANNUAL WIND ROSE
SITE:
SAN FRANCISCO WBAS
NNk-^-^"~
^^\NNE
HNl/ /' JK^ \
— -To /\ \ 3fNE
WSw\ \ /\\2
\ ^s\ / Ase
~~^\ yS£
\^0 /
SSW " "Tj sit
PERIOD
YEARS 1948-1965
Figure 4.4-2
Annual Wind Rose for San Francisco
174
FREQUENCY OF OCCURRENCE {%)
ANNUAL WIND ROSE
SITE:
UKIAH
N
wni/ / p \JW
\-U/\ / /ese
SSW ' S bbb
PERIOD
YEARS 1955-1964
Figure 4.4-3
Annual Wind Rose for Ukiah
175
FREQUENCY OF OCCURRENCE (%)
ANNUAL WIND ROSE
SITE:
SACRAMENTO
~^\NNE
x\ \ 3fNE
NlX s^C~
WNl/ / /\
Xri/
"^^^g
wsw\ \ /^^wB
\ ^/\ / /ESE
*"" SSE
PERIOD
YEARS 1966-1970
SwV /^.
\^0 /
ssw
^5
Figure 4.4-4
Annual Wind Rose for Sacramento
176
'CRESCENT CITY
KLAMATH
BLUE LAKE
.EUREKA
N^PT BRAGG
UKIAH
PT ARENA
. CALPELLA ^"*^\ <_^twiLLI>
W ' • UPPERLAKE "*^*K V
"* V • LAKEPORT ) \ )
WILLIAMS
LAKEPORT
\ wKELSEYVILLE
. — -X
• CLOVERDALE
v J
HEALDSBURG
K
• DUNNIGAN
^
HftSAN
*7\
SANTA ROSA
\ \ DAVIS •,
x# VACAVILLE
NAPA
I * F
PETALUMA' / I •
\
WOODLAND
W SACRAMENTO
SAN RAFAEL
KENTFIELD
» RIO VISTA
Figure 4.4-5
Annual Wind Roses at Selected Key Stations
in the tlkiah District
177
The annual wind roses for Areata and San Francisco
presented in Figures 4.4-1 and 4.4-2 indicate the preponderance
of onshore flow at coastal locations. The wind rose for Areata
shows a primary maximum for flow from the north- northwest which
is indicative of coastal flow conditions along much of the north
coast of California. Secondary maxima are evident for flow from
the east and south-southeast. Easterly flow is indicative of
drainage conditions from higher terrain lying east of the station
while south-southeasterly flow is indicative of prefrontal condi-
tions. At San Francisco, Figure 4.4-2 indicates a clear prefer-
ence for onshore flow from the west through northwest. The
dominance of onshore flow is clearly evident in San Francisco
with winds from all other directions occurring very infrequently.
At Ukiah, Figure 4.4-3 indicates a bimodal distribution.
Winds from the sout h- southeast occur most frequently while winds
from the west- north west clockwise through north constitute the
bulk of the remainder of the annual flow at this station. South-
southeasterly flow at Ukiah is generally indicative of upslope
flow as well as prefrontal winds. Many of the inland valley
stations in the southern portion of Ukiah District experience
prevailing flow from the southeast. Winds from the northwest
quadrant also comprise an important portion of the wind rose at
Ukiah and are indicative of the general down coastal flow experi-
enced in northwestern California.
Finally, at Sacramento, the annual wind rose shows a
clear preference for winds from the south clockwise through
southwest. This wind rose is indicative of flow in the Sacra-
mento Valley portion of the Ukiah District. Maritime air moves
into the Central Valley of California through the Carquinez
Straits and diverges both to the south towards Stockton and
Fresno and to the north to Sacramento and Redding. This flow
results in a preference for south-southwesterly flow at many
Sacramento Valley stations. In the Ukiah District, in Colusa and
Yolo Counties this flow turns more to the south-southeast as the
maritime air begins to move upslope into the valleys and the
Coast Ranges .
Seasona 1
Seasonal wind roses for Areata, Ukiah and Sacramento are
provided in Figures 4.4-6 through 4.4-8. The seasonal wind roses
for Areata are generally trimodal. During the winter months, the
primary maximum occurs for winds from the east which are repre-
sentative of nocturnal drainage conditions from elevated terrain
ly-ing east of the station. A secondary maxima is evident for
winds from the so ut h- sout hea st which are indicative of prefrontal
flow conditions which occur frequently during the rainy season
months. Finally, a tertiary maximum is evident for flow from the
nort h- northwest which is indicative of the more general down
coastal wind flow conditions commonly observed throughout north-
western California. During spring and summer, the down coastal
north-northwesterly flow represents the primary maximum at
178
FREQUENCY OF OCCURRENCE {' )
SEASONAL WIND ROSE
SITE: 2Ml~,
SSW
ALL WIND SPEEDS
ALL STABILITY CLASSES
WINTER
FREQUENCY OF OCCURRENCE (i )
SEASONAL WIND ROSE
SITE: 2i2e3
NNW^-"-"*
-\NNE
nw/ J*r
/^l4
\Mr
/ /^ yv&7
\js y^
wnii/ / /C Hr^>r
■ s\
\ jf ''-
/ "~s~sCr53l
\Jky
\ ^-"a'/^j
^\k.yyZ.
\^\ \ /^/
\ \y^l
/ /ESE
\y ^s?^ /
SwV /^-~_
/ BE
^vJO /
ssw
SSE
ALL WIND SPEEDS
ALL STABILITY CLASSES
SPRIN3
FREQUENCY OF OCCURRENCE
SEASONAL WIND ROSE
N __
SITE:
24282
NNl^
nuS Jk
"/"^i 7\
\NE
wnu^ / yc \
7C12 y\
VnE
—Je y \^^\
\ ^-A^/HS
/
\^\ \ y^ii/
^/
wShi\ \ /\jp/
/ESE
\/ \^ /
SwV 7^-^__
'SE
>jp /
SSW
5 SSE
ALL WIND SPEEDS
ALL STABILITY CLASSES
FALL
FREQUENCY OF OCCURRENCE ('. )
SEASONAL WIND ROSE
SITE: 24283
NNW^- — "
~~-^JNNE
\w[
NU/
"a^?4
/^ 7\
WNl/ / * ' ^ *
\ ^Nr
1 ^Cj2 y\
—hy \^~\
\ ^A/*s^i
\^^\ \ T^Zl
WSA. \ /\je/
/ /ese
Nv/ ^N?£ /
swV y^^_
/SE
\,2o /
SSW
5 SSE
ALL WIND SPEEDS
ALL STABILITY CLASSES
SUMMER
Figure 4.4-6
Seasonal Wind Roses for Areata
179
FREQUENCE OF OCCURRENCE
SEASONAL WIND ROSE
SITE: 23275
US-
ssu
ALL WIND SPEEDS
ALL STABILITY CLASSES
WI'.TEf
FREQUENCY OF OCCURRENCE
SEASONAL WIND ROSE
SITE: 23275
WSUP
SSU
ALL WIND SPEEDS
ALL STABILITY CLASSES
SPRING
FREQUENCY OF OCCURRENCE
SEASONAL WIND ROSE
N
7^30
SITE: 23275
NIX S^K
\lvjC
wni/ / yc
±2 /\
\ 3^NE
3fo
^H§
^ll
WSr. \ /\,
s /
/ /ESE
\s ^^ 1
Su\ y^
/SE
\^0 /
SSU
SSE
ALL WIND SPEEDS
ALL STABILITY CLASSES
SUMMER
FREQUENCY OF OCCURRENCE
SEASONAL WIND ROSE
NNW-^
WNl/ / /C V— —
SITE: 23275
"~\NNE
/^30
— --In /\ \ 3fNE
%&/ \^\ \ \
WSu\ \ /N. /
. w;> \ \y Xie/
\/ ^v£" /
SuV y^^__
^s30 /
\ *s\ / /ESE
SSU H> s>s>t
ALL WIND SPEEDS
ALL STABILITY CLASSES FALL
Figure 4.4-7
Seasonal Wind Roses for Ukiah
180
FREQUENCY OF OCCURRENCE (I)
SEASONAL WIND ROSE
wni/ / yc \
^JNNE
/S20
SITE:
sacramento
Vne
wsw\ \ /Xjg/
\56 /
ssw "
5 SSE
/ese
WINTER
FREQUENCY OF OCCURRENCE (%)
SEASONAL WIND ROSE
FREQUENCY OF OCCURRENCE {%)
SEASONAL WIND ROSE
WNl/ / /C V
SITE:
SACRAMENTO
~~-\NNE
— /r JX \ 3fNE
WSw\ \ /^NA^g/^^
\§0 /
. ssw^ '
r \ -/\ / /ESE
— — -~^\ /**■
5 " SSE
SUMMER
FREQUENCY OF OCCURRENCE (S)
SEASONAL WIND ROSE
SITE:
SACRAMENTO
N9c
WNl/ /
KINt^-"
Xne
\ 3fNE
wsw\ \
/ /ESE
\^e /
ssw '
5 " SSE
FALL
Figure 4.4-8
Seasonal Wind Roses for Sacramento
181
Areata. The secondary maximum for winds from the east and south-
southeast occurs much less frequently during these months. By
fall, however, the nocturnal drainage flow conditions from the
east once again dominate with secondary maxima for flow from the
nort h- northwest and sout h- southeast .
At Ukiah, Figure 4.4-7 indicates a bi modal distribution
aligned along a sout h- sout heast/ nort h- northwesterl y axis, which
is well aligned with the Russian River Valley. During winter,
upslope flow from the south-southeast clearly dominates as this
also represents winds associated with prefrontal conditions.
During spring and summer, winds from the northwest quadrant
dominate, however, upslope flow from the south- southeast still
occurs with a fairly substantial frequency of occurrence. The
downslope northwesterly flow observed at Ukiah during the warm
season months is indicative of conditions throughout this portion
of California resulting from the influence of the semi -permanent
Pacific high pressure system. By fall, the distribution is
nearly split between flow from the so uth- southeast and northwest.
This season represents a transition period between the influence
of the Pacific high pressure system and the onset of migratory
storm systems which move through the Pacific northwest during the
rai ny season .
Finally, at Sacramento, the seasonal distribution is
indicative of conditions observed in the Sacramento Valley por-
tion of Ukiah District. During spring, summer and fall, south-
west and sout h- southwes terl y flow dominate at Sacramento while
southeasterly winds are prevalent during the winter months. A
secondary maximum occurs for nort h- northwesterl y flow during all
seasons. Once again, these latter winds are indicative of pre-
vailing flow throughout northwestern California while southeast-
erly winds represent a combination of upslope flow and prefrontal
wi nds .
4.4.2
Diurnal Wind Distribution
The diurnal distribution of both wind speed and direc-
tion provides average values of these parameters as a function of
the hour of the day. Such data provides useful additional infor-
mation on the dispersion characteristics of a given geographical
area. For example, the diurnal distribution of wind direction
provides a good indication of when certain downwind areas could
be impacted by sources of air pollutants. In addition, the
diurnal distribution of wind speed provides an indication of the
time of day when best dispersion conditions can be expected based
upon average wind speeds and the associated degree of pollutant
transport. This is important to know in activities such as
prescri bed f i res .
Wind Direction
Figures 4.4-9 and 4.4-10 present the diurnal wind direc-
tion distribution for Areata and Ukiah. These data provide
insight into the direction of the prevailing winds as a function
182
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{ttHU nMlN} KIUH10 (WIN
183
of time of day. This information can be valuable to community
and industrial planners concerned with the control of existing
emission sources and the placement of new sources since they can
be used to determine which specific areas in a region are most
likely to be adversely impacted by pollutants throughout the day.
The diurnal distribution of wind direction at Areata as
depicted in Figure 4.4-9 indicates the prevalence of easterly
drainage flow from higher terrain lying east of the station
during the evening and early morning hours. From mid-morning
till sunset, the flow becomes generally northwesterly to west-
northwesterly as the onshore flow of maritime air prevails.
Further inland at Ukiah, flow from the so uth- southeast prevails
during the nighttime and early morning hours. This is indicative
of valley flow conditions. During the afternoon, flow from the
northwest quadrant dominates as northwesterly flow indicative of
conditions throughout this portion of the state begins to domi-
nate .
Wind S peed
The wind speed distributions at Areata and Ukiah are
very similar as indicated in Figures 4.4-11 and 4.4-12. Wind
speeds are generally lighter at Ukiah than at the more exposed
coastal station of Areata. At both stations, minimum wind speeds
occurr during the early morning hours between midnight and
approximately sunrise. Maximum wind speeds occur at Areata
between one and three in the afternoon and around four to five in
the afternoon at Ukiah. Maximum wind speeds at Areata average 4
meters per second (9 mph) with minimum wind speeds of roughly 1.7
meters per second (3.8 mph). At Ukiah, maximum wind speeds reach
approximately 3 meters per second (6.6 mph) during the afternoon
with overnight values reaching as low as 0.5 mps (1.1 mph).
In summary, available diurnal wind speed data for Areata
and Ukiah show similar distributions with wind speeds being
lighter at the inland station, Ukiah. Wind speeds will tend to
be higher along coastal regions of the Ukiah District and at
exposed sites in rugged mountainous terrain. Wind speeds would
be lowest in sheltered valley locations within the Coast Ranges.
4.4.3
Wind Speed Distribution
The distribution of wind speed as a function of the
frequency of occurrence of designated wind speed categories is
routinely available for first order stations within the Ukiah
Di-strict. Figures 4.4-13 t hrou g h 4. 4 -1 5 provide seasonal and
annual distributions of wind speed as a function of six distinct
categories including; (1) 0-3 knots (0-3.5 mph), (2) 4-6 knots
(4.6-6.9 mph), (3) 7-10 knots (8.1-11.5 mph), (4) 11-16 knots
(12.7-18.4 mph), (5) 17-21 knots (19.6-24.2 mph), and (6) greater
than 21 knots (24.2 mph). The frequency of calms is also pro-
vided in each figure as well as conversion factors to facilitate
the use of both English and metric units.
184
6 -
5 -
in A —
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c
1 -
0 -
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8 obssrvations
per day
m
v
V
00 02 04 06 08 10 12 14 16 18 20 22 24
Hour of the Day (PST)
Figure 4.4-11
Diurnal Wind Speed Distribution at
Areata, CA* (1968-1972)
6 -
Q.
4 -
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QJ
Q.
T3
0 -
•--' — ^l—^*-*
00 02 04 06
08 10 12 14 16
Hour of the Day (PST)
18 20 22 24
Figure 4.4-12
Diurnal Wind Speed Distribution at
Ukiah, CA (1955 - 1964)
Note: Diurnal Wind Speed as Defined by Magnitude Average SDeed
1 MPS = 2.237 MPH = 1.944 Knots 10c
lob
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WINTER
33
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23.0
26.0
4.
FREQUENCY OF
CALKS:
22.6%
2.5 0.8
0-3 4-6 7-10 11-16 17-21
MIND SPEED CLASS (WOTS)
21*
60
SPRING FREOUENCY Of
=■ 50
CALMS: 24.0%
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SUMMER
FREQUENCY OF
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win: SPEED CLASS (KNOTS)
21<
4-6 7-10 11-16 17-21
WIND SPEED CLASS (KNOTS)
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ANNUAL FREQUENCY OF
CALMS: 25^o/o
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23.7
12.2
2-3 0.2
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MIND SPEED CLASS (WOTS)
21-
Figure 4.4-13
Annual-Seasonal Frequency of Occurrence of Key Wind Speed Classes
at Areata, California (1968-1972)
Note: IMPS = 2.237 MPH = 1.944 Knots
186
to
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&
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71.8 WINTER
FREQUENCY OF
CALMS:
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12.5
11.4
3.9
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0.2 <0.1
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MIND SPEED CLASS (KNOTS)
21*
4-6 7-10 11-16 17-21
MIND SPEED CLASS (KNOTS)
60
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£ io
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SUMMER
17.0
23.8
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frequency or
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0.2
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0-3 4-6 7-10 11-16 17-21 21<
WIND SPEED CLASS (KNOTS)
60
H 50
| 40
S»
o
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0
69.5
1.5
FALL
13.7
4.1
JZL
FREQUENCY OF
CALMS: 65.2%
0.2 <0.1
0-3 4-6 7-10 11-16 17-21
WIND SPEED CLASS (KNOTS)
21«
*•
— 50
61 -7 ANNUAL
FREQUENCY OF
CAL«:57.6%
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£ 20
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7
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WIND SPEED CLASS (WOTS)
21*
Figure 4.4-14
Annual-Seasonal Frequency of Occurrence of Key Wind Speed Classes
at Ukiah, California (1955-1964)
187
r\ n T7 MH I I
i n A A I/.
to
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I 40
6 20
g
£ K
0
WINTER
FREQUENCY Of
"^14.35
33.1
29.
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22.3
12.1
2.4
m
0-3 4-6 7-10 11-16 17-21
WIND SPEED CLASS (WOTS)
0.6
21*
60
S SO
40
30
" 10 h
30.6
20 - 18.9
SPRING
28.4
19.7
FREQUENCY OF
CALMS: q oo/
2.0
JZL
0.4
0-3 4-6 7-10 11-16 17-21 21*
WIND SPEED CLASS (KNOTS)
tC
^^
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SO
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—
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B
a
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H
30
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E io
34.4
12.4
SUMMER
35.6
16.8
FREQUENCY OF
BUB! 4.6%
0.8 <Q.1
0-3 4-6 7-10 11-16 17-21
WIND SPEED CLASS (KNOTS)
21-
H 50
UJ
FALL
FREQUENCY OF
MLK: 14.9%
1 *°
36.6
o
" 10
19.
6
21.
1
10.8
1.7 0.2
0
i — i — ,
0-3 4-6 7-10 11-16 17-21
WIND SPEED CLASS (KNOTS)
21-
0-3 4-6 7-10 11-17 17-21
MIND SPEED CLASS (WOTS)
21-
Figure 4.4-15
Annual-Seasonal Frequency of Occurrence of Key Wind Speed Classes
at Sacramento, California (1966-1970)
Note: IMPS = 2.237 MPH = 1.944 Knots
188
The figures indicate that light wind speed conditions
tend to reach a maximum frequency during winter and fall at each
station. The 0-3 knot class reaches a maximum frequency of 30.9%
of all occurrences at Areata during this season and accounts for
29.6% of the fall distribution at Sacramento. At tiki ah, the
frequency of calm and light wind speed conditions is exceptional-
ly high. The frequency of calms reaches 68.2% of the distribu-
tion during winter and 65.2% of the distribution during fall at
this station. The 0-3 knots wind speed category clearly domi-
nates the distribution during all seasons reaching a minimum
frequency in summer when surface heating induced upslope flow
creates stronger afternoon winds. The very high frequency of
light wind speed conditions at Ukiah is conducive to air pollut-
ant buildups, particularly during the fall and winter seasons at
Ukiah.
The 4-6 knot wind speed category is the most common
category at Areata reaching a maximum frequency of 41% of all
occurrences during fall. On an annual basis, this wind speed
category occurs 35.2% of the time. At Ukiah, on an annual basis,
the 0-3 knot wind speed category occurs 61.7% of the time with
the second most frequently occurring category being the 7-10
class which occurrs 17.7% of the time. Fully 57.6% of all wind
speed occurrences at Ukiah are calm conditions.
Finally, at Sacramento, the 4-6 knot wind speed class is
the most common during all seasons with the exception of summer
when the 7-10 knot wind speed class dominates. During the summer
months, the influx of maritime air through the Carquinez Straits
into the Sacramento Valley results in brisk afternoon winds at
Sacramento and at all portions of the Ukiah District in the
Sacramento Valley. On an annual basis, the 4-6 knot wind speed
class occurrs most frequently at Sacramento accounting for 33.7%
of the distribution with calms accounting for 10.7% of all occur-
rences .
Wind Speed as a Function of Wind Direction
The distribution of wind speed as a function of wind
direction provides important information for dispersion meteor-
ological studies. For example, when sensitive areas are situated
near possible sources of pollutants, it is often beneficial to
examine the mean wind speed of the flow from the direction of the
source. Very low wind speeds are generally associated with
stable or limited dispersion conditions and could serve to maxi-
mize pollutant impact in the sensitive area. High average wind
speeds generally imply well-mixed conditions and would reduce
downwind pollutant concentrations. Plots of annual average wind
speed as a function of wind direction have been generated for
Areata, Ukiah and Sacramento and are presented in Figures 4.4-16
through 4.4-18. In addition, the average annual wind speed
independent of wind direction for each station is presented with
each pi ot .
189
Q-
Annual Averaqe
6.8
N NNE NE ENE E ESE SE SSE S SSW SW WSW W WNW NW NNW N
Wind Direction
(Wind From)
Figure 4.4-16
Annual Wind Speed as a Function of Wind Direction
at Areata, California (1968-1972)*
8 Observations per day
190
UJ
Q-
Annual Average
3.6
N NNE NE ENE E ESE SE SSE S SSW SW WSW W WNW NW NNW N
Wind Direction
(Hind From)
Figure 4.4-17
Annual Wind Speed as a Function of Wind Direction
at Ukiah, California (1955-1964)
191
CO
Average
Annual
7.5
N NNE NE ENE E ESE SE SSE S SSW SW WSW W WNW NW NNW N
Wind Direction
(Wind From)
Figure 4.4-18
Annual Wind Speed as a Function of Wind Direction
at Sacramento, California (1966-1970)*
8 Observations per day
192
The data for Areata indicate that the strongest wind
speeds are associated with winds from the prevailing directions.
Winds from the northwest quadrant account for the strongest wind
speeds at this station as maritime air flows into the area unin-
hibited by terrain influences. Wind speeds in excess Of 10 miles
per hour are common for onshore flow. Winds from the southeast
quadrant commonly associated with prefrontal conditions are also
accompanied by fairly brisk wind speeds, generally on the order
of 10 miles per hour. Lightest wind speeds are associated with
uncommon directions and for drainage flow from the east. Drain-
age flow conditions are generally typified by winds of 6-7 miles
per hour.
Figure 4.4-17 indicates that at Ukiah, strongest wind
speeds are associated with flow from the southeast indicative of
upvalley flow. Winds from this direction represent prevailing
winds during most seasons of the year at this station. Wind
speeds approaching 10 miles per hour are not uncommon for flow
from these directions. The second highest wind speeds are gen-
erally associated with flow from the northwest quadrant which is
indicative of regional flow conditions associated with down
coastal winds common in northwestern California. Northwesterly
flow is generally characterized by winds of between 8 and 10
miles per hour at Ukiah. The annual average wind speed is con-
siderably lower than wind speeds shown for most wind directions.
This can be attributed to the very high frequency of calms at the
Ukiah Station.
Finally,
the highest wind
from the south and
westerly flow are
10 miles per hour
at Sacramento, the same trend continues with
speeds being associated with prevailing flow
from the northwest. Southerly flow and north-
both characterized by wind speeds in excess of
The southerly flow is generally associated
with summer sea breeze situations. Northwesterly flow is again
indicative of regional flow conditions commonly observed in this
part of the state. The annual average wind speed at Sacramento
is 7.5 miles per hour .
4.4.4
Persistence Analyses
The persistence of both wind speed and wind direction
also plays a very functional role in a complete analysis of
dispersion meteorology. For example, the persistence of a par-
ticular wind direction provides information relative to the
likelihood of continued impact at a given receptor location for
either existing or proposed sources. In terms of wind speed, low
wind speeds can often provide a maximum impact in a given region
particularly if they persist for any length of time. Therefore,
the persistence of calms or lower wind speed classes can also
provide very useful information relative to the overall disper-
sion potential.
193
Tables 4.4-1 and 4.4-2
speed persistence tables for
three hourly basis at Areata
tence analyses. These data
tence of these parameters in
are provided in terms of key
24 or more hours .
provide wind direction and wind
Ukiah. Data are only available on a
eliminating its utility for per sis-
provide information on the persi s-
the primary BLM land area. The data
persistence intervals of 2, 4, 10 or
4.4.5
Trajectory Analyses
Trajectory analyses are
to describe regional transport,
oped through the identification
tions to establish the mean flow
These data are then useful in
scale transport of pollutants.
used in dispersion meteorology
Trajectory analyses are devel-
of prevailing flow at key sta-
over a large geographical area.
determining the probable large
In the Ukiah District, diurnal wind direction data are
only availabe for Areata and Ukiah. It is not felt that the
available data on prevailing flow at these stations is sufficient
to definitively determine the actual trajectory of air parcels
throughout this large area. A general trajectory analyses is
presented in Figure 3.6-3. The reader is cautioned in the inter-
polative use of these data for other areas as local terrain
effects may dominate. However, some useful conclusions can be
drawn from the analysis.
4.4.6
Winds Aloft
Upper level winds provide a measure of the mean trans-
port above the surface boundary layer. However, upper air data
are only available for a very few NWS station locations and, for
this reason, most major pollutant studies require the collection
of onsite data to provide a measure of winds aloft. In Cali-
fornia, upper air data are only routinely collected by the NWS at
Oakland, Santa Monica and San Diego.
Upper level wind data at such NWS stations are generally
taken by radiosonde. This is a balloon, tracked by radar which
transmits data on temperatures aloft as well as wind speed and
wind direction through the tracking of the balloon's downwind
position. Upper level winds over most of California show a
characteristic flow from the northwest quadrant at most levels.
The impact of the dominating terrain characteristics of much of
California and the Ukiah District is felt most critically in the
first few thousand feet, the area of interest in pollution
st-ud i es .
As stated previously, Oakland is the only regular upper
air meteorological station operated by the NWS near the Ukiah
District. Other winds aloft data have been collected by the
(California Air Resources Board) CARB as part of its ongoing
analysis of pollutant transport conditions as well as for use in
the development of burn/no-burn forecasts. This data collection
194
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195
program by the CARB is primarily geared to the identification of
local inversion meteorology and the establishment of the mean
height of the mixing layer. Data available from pilot balloon
releases by the CARB as well as through programs operated by
private industry indicate a continuation of the flow observed at
the surface gradually turning towards the west through northwest
as commonly observed over California at upper levels.
Holzworth (1972) has provided seasonal and annual values
of the mean wind speed averaged through the mixing layer for both
the morning and afternoon hours. These data are particularly
useful in dispersion studies as they provide a realistic measure
of mean transport in the layer of the atmosphere in which most
pollutants are mixed.
Table 4.4-3 provides a summary of these data for the
Ukiah District. The data provide a range of values across the
district which indicate that lower wind speeds occur during the
morning hours as opposed to the afternoon. In addition, winter
and fall tend to be the most restrictive seasons in terms of
lower wind speeds. A review of the geographical distribution of
these data as provided by Holzworth (1972) indicates that the
lower values occur in the interior with higher wind speeds gen-
erally along the Pacific Coast. It is pointed out, however, that
the Holzworth (1972) data are based upon an analysis of data
available from Oakland, Santa Monica and San Diego and as such
are based upon very few data points. For this reason, the reader
is cautioned in the utilization of these data, particularly in
areas with important terrain effects.
The CARB data indicates that weak mixing layer winds are
known to occur during summer at Ukiah. Mixing layer wind speeds
are strong at Ukiah during winter. Other seasonal mixing layer
wind speeds are not notable at Ukiah, the station that has been
studied by the CARB (1974).
196
Table 4.4-3
Seasonal and Annual Average Wind Speeds (MPH)
in the Mean Mixing Layer Over the Ukiah District
Morning
Afternoon
Winter
4.5 - 8.9
8.9 - 11.2
Spring
6.7 - 8.9
13.4
Summer
4.5 - 6.7
11.2 - 13.4
Fall
4.5 - 6.7
8.9 - 11.2
Annual
6.7
11.2
197
4.5
ATMOSPHERIC STABILITY
The definition of atmospheric stability throughout the
Ukiah District is a critical component of the dispersion meteor-
ological analysis. Section 4.2.2 provides a detailed discussion
of atmospheric stability and its role in defining the dispersion
of airborne effluents. Figure 4.5-1, which also appears in
Section 4.2.2, summarizes the dispersion characteristics associ-
ated with the various stability categories for the traditional
dispersion scenarios. This section provides analyses that are
designed to identify specific characteristics of atmospheric
stability. These analyses include:
t Seasonal and Annual Distributions
• Diurnal Distributions
• Persistence Analyses
• Stabi 1 i ty Wind Roses
These analyses describe a key component of the disper-
sion characteristics of the Ukiah District. Data are unfortu-
nately available for only a few key stations in the region and
the reader is cautioned in the use of these analyses, particular-
ly in areas of rugged terrain or other locations not well repre-
sented by the available data.
4.5.1
Seasonal and Annual Stability Distributions
Annual stability distributions provide a means of quan-
tifying the atmospheric dispersive power of an area in an easily
comparative form. The seasonal variations in stability reflect
the extent to which the dispersive power of the atmosphere
changes with the seasons.
The ability of the local atmosphere to disperse airborne
effluents from specific source types can be discussed in terms of
atmospheric stability. When the atmosphere is stably stratified,
the impact of ground level, non-buoyant emissions, will be great-
est as both vertical and lateral diffusion are restricted.
Examples of such emissions include automobile exhaust and fugi-
tive dust. Typical similar sources which might impact BLM lands
include range management activities and the use of unpaved sur-
face roads. The lower atmosphere is most likely to be stable on
calm clear nights when cold air tends to collect at lower eleva-
tions. Emissions from tall stacks under such conditions will
have little or no impact at ground level as the plume remains
relatively intact aloft. Fall and winter are the seasons when
su-ch conditions occur most frequently in California and in most
areas of the United States. The impact of ground level sources
is therefore at a maximum during these seasons.
Intense surface heating results in considerable convec-
tive activity and unstable conditions. Under such conditions,
vertical diffusion is considerable and "fumigation" can occur as
198
Stability Category A-C; Looping
Stability Category D; Coning
Stability Category E-G; Fanning
I i. ts&—iL . ■ u I .I'M
Stability Categories As Noted,
Lofting
E-G
Stability Categories As Noted;
Fumigation
E-G
A-C
Stability Categories As Noted;
Trapping Inversion
Figure 4.5-1
i
Typical Plume Behavior
E-G
A-D
Plume behavior influenced by the temperature lapse rate above and below the
release height. The dashed lines in the profiles are the adiabatic lapse
rates, included for reference, while the solid lines indicate the actual
lapse rate. The Pasquill stability categories are also provided.
199
emissions from elevated sources are brought rapidly to the sur-
face creating maximum ground-level concentrations. Examples of
large elevated pollutant sources which could potentially impact
BLM lands include power plants and other large industrial sources
as well as large forest fires.
Finally, neutral atmospheric stability, characterized by
a windy, well-mixed atmosphere, and generally indicative of good
atmospheric dispersion, can result in locally high ground-level
concentrations for stacks of intermediate height or stacks whose
height is not substantially greater than the height of surround-
ing buildings. Most moderate sized industrial complexes are
indicative of this source type; refineries and other processing
industries serve as typical examples. In such cases, strong
winds can bring the plume rapidly to the surface, resulting in
high gound-level pollutant concentrations in a condition known as
"downwash". Neutral conditions may also result in the re-en-
trainment of loose dust and soil particles associated with des-
erts and overgrazed arid lands. Reduced visibility and increased
atmospheric particulate loading may occur in nearby populated
areas as a resul t .
The following discussion provide seasonal and annual
distributions of atmospheric stability which, combined with a
knowledge of source types, can be used to identify probable
periods of maximum impact. Seasonal and annual stability fre-
quency distributions for various site locations throughout the
Ukiah District are provided in Figures 4.5-2 through 4.5-4. At
Areata, neutral conditions dominate the stability distribution
during all seasons of the year. On an annual basis, neutral
conditions acccount for 60.9% of the distribution while stable
conditions account for 25.9% of the distribution. Unstable
conditions at Areata are fairly infrequent. The frequency of
neutral conditions in Areata is highest in the summer months
coinciding with the high frequency of occurrence of fog and
stratus. Unstable conditions also reach the highest frequency of
occurrence during this season when surface heating effects tend
to become most intense. As a result, the frequency of stable
conditions is at a low during the summer months. Fall tends to
be the season with the lightest wind speeds and the highest
frequency of clear skies in Areata. Accordingly, the frequency
of stable conditions reaches a seasonal maximum at 34.2% of the
distribution.
At Ukiah, the frequency of neutral conditions is greatly
diminished over that observed at Areata. The inland more conti-
nental nature of this station results in a greatly enhanced
frequency of stable conditions. On an annual basis, neutral
conditions occur just 26.3% of the time while stable conditions
account for 34% of the distribution. Seasonally, neutral condi-
tions are highest in winter when the frequency of migratory low
pressure systems reaches a peak. This is the rainy season in
California and neutral conditions are generally associated with
inclement weather. Stable conditions occur more frequently than
200
&s
UJ
dc
cc
ZD
o
<_>
o
>-
dc
60
50
40
30
20
10 \
WINTER
-
62.3
-
28.8
-
8.9
^*5
60
UJ
50
z
UJ
dc
DC
Z3
40
<_>
O
o
u.
30
o
>-
o
20
Ul
rs
O"
LU
dc
10
_
SPRING
62.6
-
^
23.4
14.0
UNSTABLE
NEUTRAL
STAPLE
UNSTABLE
NEUTRAL
STABLE
o
DC
DC
ZD
O
<_>
o
O'
UJ
DC
/U
60
67.0
Suhiilk
50
40
30
20
15.7
17.3
10
U
u
MSTABL
E I
IEUTRAI
5TABLE
70
DC
DC
ZD
o
o
ZD
Cr
70
60
^3
50
UJ
O
zr
UJ
40
=3
O
< >
o
30
u.
o
>-
20
2:
UJ
ZD
o-
UJ
10
DC
0 UNSTABLE NEUTRAL STABLE
UNSTABLE NEUTRAL STABLE
Figure 4.5-2
Seasonal/Annual Distribution of Atmospheric Stability at Areata, Ca,
201
cc
cc
o
>-
70
60
50
40 *-
o-
1 1 1
* 10 h
20 - 18.6
UN STAB L
WINTER
38.4
43.0
NEUTRAL
STAELE
UNSTABLE
STABLE
CL
CC
I
o
o
>-
Lu
CC
60
SUMMER
50
-
43.8
44.2
40
30
20
12.0
10
U
U
NSTABL
E
MEUTRAL
STABLE
o
cc
cc
<_)
o
o
>-
o-
CC
70
60
50
40
30
20
10
0
29.8
cc
cc
o
<_>
o
cr
LlJ
CC
70
60
50
40
30
20
10
FALL
28.0
ANNUAL
43.9
26.3
UNSTABLE
22.6
0 UNSTABLE NEUTRAL STABLE
49.4
NEUTRAL STABLE
Figure 4.5-3
Seasonal/Annual Distribution of Atmospheric Stability at Ukiah, Ca
202
70
o 60
o
uj 50-
UJ
o
O
° 30h
o 20
c
UJ
10
0
WINTER
53.7
_
36.2
—
10.1
o
o
<_>
cc
cc
zz>
o
<_>
o
>-
O
UJ
UNSTABLE NEUTRAL STABLE
UNSTABLE
NEUTRAL STABLE
70
70
o 60
SPRING
o
uj 50
UJ
oc 40
ID
26.2
35.2
38.6
O
o
° 30
< — i
FREQUENCY (
o o
o
UNSTABLE NEUTRAL
STABL
7
/u
SUMMER
60
50
"5P Q
41.5
40
jo . y
30
20
19.6
10
_
0
o
o
C_)
DC
ac
ZD
o
c_>
o
o
cr
UJ
ac
FALL
60
50
48.0
40
30
20
—
27.8
LH .L
10
0
UN
STABL
E
NEUTRAL
STABLE
UNSTABLE NEUTRAL STABLE
Figure 4.5-4
Seasonal/Annual Distribution of Atmospheric Stability
Sacramento, California
203
either neutral or unstable conditions during all seasons of the
year. The frequency of stable conditions reaches a peak during
fall when it accounts for 35.6% of the seasonal distribution.
This is in agreement with the distribution of stable conditions
seasonally at Areata. Throughout northwestern California, fall
is the season with lightest wind speeds accompanied by a high
frequency of occurrence of poor ventilation conditions. Unstable
conditions reach a maximum frequency during summer when they
of the distribution. This is the only season
unstable conditions occur more frequently than
stable conditions. Unstable conditions domi-
season as surface heating becomes intense re-
sulting in considerable convective activity. This is also the
season with the maximum number of thunderstorms occur in this
area , once again, indicative of an unstable atmosphere.
account for 43.8%
of the year when
either neutral or
nate during this
Finally, the Sacramento data presented in Figure 4.5-4
present an indication of stability distributions within the
Sacramento Valley portion of the Ukiah District. At this loca-
tion, considerable variation exists between seasons. On an
annual basis, stable conditions dominate the distribution ac-
counting for 41.1% of the distribution with neutral conditions
occurring with the next highest frequency of occurrence. Season-
ally, neutral conditions dominate the winter distribution due to
a combination of the frequent occurrence of low clouds and fog as
well as the passage of storm systems. During this season, neu-
tral conditions account for 53.7% of the distribution at Sacra-
mento. During all other seasons of the year, stable conditions
dominate, once again, reaching the highest frequency of occur-
rence of 48% of the fall distribution. Once again, this is
indicative of the pattern observed throughout the Ukiah District
during the fall months. Unstable conditions reach their peak in
summer accounting for 38.9% of the distribution.
4.5.2
Diurnal Stability Distributions
The diurnal distribution of stability provides a means
of determining the probability that any one category will occur
at any given hour of the day. This information, together with
the seasonal and annual stability distributions, provides a com-
plete picture of the stability characteristics at any given
station. Since most human and industrial activity is generally
concentrated during the daylight hours, the diurnal stability
distributions allow for intensified study of the dispersion
conditions prevalent during those and other pertinent periods.
The diurnal stability distributions for the four sta-
tions for which digitized data were available are presented in
Table 4.5-1 and Figure 4.5-5. These data were averaged over the
respective periods of record for each station, and as such are
representative of an annually averaged day; seasonal -variations
are not expected to be significant on a diurnal basis.
204
Table 4.5-1
Diurnal Frequency Distribution
of Stability in the Ukiah District
Hour
Areata
Ukiah
U
N
S
U
N
S
1
0
56.2
43.8
0
19.1
80.9
2
*
0
20.6
79.4
3
•
0
21.5
78.6
4
0
59.1
40.9
0
22.3
77.7
5
*
0
24.3
75.8
6
•
0
25.6
74.3
7
11.6
63.2
25.3
12.4
28.6
59.0
8
38.7
28.8
32.6
9
56.5
29.4
14.0
10
35.2
64.8
0.0
72.8
27.3
0
11
75.5
25.5
0
12
77.2
22.8
0
13
40.4
59.6
0.0
77.5
22.5
0
14
76.0
24.0
0
15
70.9
29.1
0
16
18.1
76.8
5.1
64.6
35.5
0
17
50.6
40.3
9.1
18
29.2
42.7
28.2
19
0
56.4
43.6
13.6
38.1
48.3
20
0
24.2
75.8
21
0
21.3
78.7
22
0
51.4
48.6
0
20.1
79.9
23
0
18.4
81.6
24
0
19.0
81.0
U = Unstable
N = Neutral
S = Stable
205
O
O
o
o o o o
^J- CO C\J r—
jQ
+->
CD
4->
o
Q.
S_
cu
CO
+J
r— r—
CD
O
CO
J3 fO QJ
1
F
•i —
TO S-r-
Lfi
+->
Q
+-> -PJ3
.
<C
CO Z5 <T3
•St
-£Z
C (D-P
4-
fO
ZD ZOO
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O
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ZJ
C
ZZ>
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CT.
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• i —
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Ll_
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JZ)
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00
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206
As can be seen from the table, both stations exhibit
very sharp increases in stable conditions after about 1600 PST
and very sharp decreases at 0800 PST. These times correspond
with the average limits of sunset and sunrise, respectively, on
an annual basis. The maximum frequency of stable conditions
occurs during the middle of the night at both stations.
The onset of unstable conditions closely matches the
rapid decay of stable conditions near sunrise. Conversely,
unstable conditions decay rapidly at the onset of stable con-
ditions near sunset. The overlaps evident in the stable and
unstable categories in Table 4.5-1 are a result of the annual
variations in the onsets of sunrise and sunset; seasonal plots of
the diurnal stability distributions would serve to reduce these
overlaps. The maximum frequency of unstable conditions occurs
at 1300 PST at both stations. Again, as would be expected from
the definition, unstable conditions do not occur at any station
after radiational sunset and before radiational sunrise.
Neutral conditions are shown to occur at all hours of
the day, showing a tendency to occur more frequently during the
late afternoon hours at both stations.
4.5.3
Stability Persistence
Stability persistence tables give an indication of the
tendency of a stability category to persist for extended periods
of time. This information can be used to identify the frequency
of the persistence of adverse dispersion conditions. For exam-
ple, long periods of very stable conditions, will maximize the
impact of vehicular emissions. In this way, adverse dispersion
conditions can be related to specific pollutant sources.
Table 4.5-2 presents the stability persistence tables
for Ukiah, the only station for which suitable hourly data are
available. These tables are representative of a typical annual
period. The values in the tables reveal the percentage of time
that a given stability class persisted for a given number of
hours at each station.
4.5.4
Stability Wind Roses
Stability wind roses provide information useful for
determining land use alternatives in terms of the probable trans-
port and dispersion of airborne pollutants. The data are pre-
sented for three major classes which represent a combination of
the Pasquill categories; (1) unstable (A-C), (2) neutral (D) and
(3) stable (E-G). As noted earlier, maximum ground level pol-
lution impacts vary with each stability category as well as with
source emission types and levels.
Once again, stable conditions are generally character-
ized by light winds, hence, wind roses for this stability cate-
gory are valuable in determining probable levels and areas of
207
Table 4.5-2
Persistence of Stability Class
(Percentage of Total Observations)
at Ukiah, CA (1955-1964)
No. of Hours
Stability
Persisted
U
N
S
1
31.0
23.2
45.8
2
22.7
20.7
42.7
3
14.9
18.8
40.5
4
9.8
17.3
38.9
5
6.0
16.0
37.8
6
3.7
15.0
36.6
7
1.7
14.1
35.5
8
0.4
13.2
34.4
9
0.1
12.5
32.9
10
0.1
11.7
30.4
11
0
11.0
27.4
12
0
10.3
22.1
13
0
9.9
17.1
14
0
9.5
13.0
15
0
9.0
9.5
16
0
8.6
5.5
17
0
8.3
2.8
18
0
7.8
0
19
0
7.4
0
20
0
6.7
0
21
0
6.4
0
22
0
5.9
0
23
0
5.6
0
24
0
5.3
0
25
0
4.91
0
or more
Unstable
Neutral
Stable
208
maximum impact from the low-level, non-buoyant emissions associ-
ated with many rural land uses, such as grazing and farming.
Alternatively, neutral conditions with high wind speeds or un-
stable conditions can result in maximum impacts from elevated
plume sources associated with heavier industrial activity.
Figures 4.5-6 and 4.5-7 provide stability wind roses as
well as the annual wind rose for Areata and Ukiah. As indicated
earlier, stability class I refers to unstable conditions, stabil-
ity class II refers to neutral conditions, and stable conditions
are represented by stability class III. Each of the stability
wind roses can be summed for comparison with the annual wind rose
also depicted on each figure.
Figure 4.5-6 provides stability wind roses as well as
the annual wind rose for Areata, California. The figure shows
that stable conditions are almost exclusively associated with
nocturnal drainage flow from higher terrain lying east of the
city. Neutral conditions, on the other hand, are well distrib-
uted and are represented by flow from each of the tertiary maxima
that make up the annual wind rose. North- northwesterl y flow is
most frequently associated with neutral conditions and is indica-
tive of general maritime flow of air down the northern Califor-
nian coast in this region. Unstable conditions occur ^ery infre-
quently at Areata and are almost exclusively associated with flow
from the northwest quadrant. This primarily occurs during situa-
tions when sunny skies prevail associated with a light onshore
f 1 ow.
The stability and annual
form' a are provided in Figure 4.5-
that stable flow is once again assoc
wind conditions associated with down
the Russian River Valley. Accord in
quadrant dominates for stable flow
tions are generally associated wi
which is indicative of conditions as
system passage. Finally, unstable
uted between both the southeaster
observed at this site. Unstable co
high frequency during the warmer mon
directions are well distributed.
wind roses for Ukiah, Cali-
7. The wind roses indicate
iated with nocturnal drainage
valley flow along the axis of
gly, flow from the northwest
conditions. Neutral condi-
th south- southeasterl y flow
sociated with migratory storm
conditions are well distrib-
ly and northwesterly maxima
nditions occur with a fairly
ths of the year when the wind
209
i FREQUENCY OF OCCURRENCE (I)
ANNUA! WIND ROSE
SITE:
ARCATA
NNK-^"^
"---\NNE
\ne
NU/
^/^
"""/^ Xs
WNl/ / /\| \^*
\ \fNE
\k/ \^\
\ \
wsw\ \ A^J
/ /ESE
\X ^16/
Sw\ y-^^__
/SE
\2e /
SSw
5 SSE
AIL WIND SPEEDS
PERIOD
YEARS 1968-1972
FREQUENCY OF OCCURRENCE (%)
ANNUAL WIND ROSE
wNi/ / yc \
~^NNE
SITE:
ARCATA
N,NE
\ 3ENE
WSw\ \ /\o2/
Sw\ ^-~-^_
SSW '
ALL WIND SPEEDS
STABILITY CLASS 1
S SSE
/ /ESE
/SE
PERIOD
YEARS 1968-1972
FREQUENCY OF OCCURRENCE [%)
ANNUAL WIND ROSE
SITE:
ARCATA
NNW^ '
\NNE
nu( J*r
\nE
wni/ / y( fvV"
\ 3ene
-~ti*/ v^^\
wsw\ \
/ \w
/ /ESE
\/ \46 /
swV y^_^_
/SE
\§e /
ssw '
S SSE
ALL WIND SPEEDS
STABILITY CLASS 2
PERIOD
YEARS 1968-1972
FREQUENCY OF OCCURRENCE (%)
ANNUAL WIND ROSE
SITE:
ARCATA
NNk^- — """
-^NNE
\nE
NW/ Jr
/"^v
/^l /
wni/ / yc V— —
—fi*/ V^- \
\ 3fNE
N
w
sw\ \ /No?/
/ /£SE
\X \l£/
Sw\ y^->^__
SS£
\20 /
SSW^~~"
S " SSE
ALL WIND SPEEDS
STABILITY CLASS 3
PERIOD
YEARS 1968-1972
Figure 4.5-6
Stability Wind Roses for Areata, California
210
FREQUENCY OF OCCURRENCE (%)
ANNUAL WIND ROSE
SITE:
UKIAH
-^NNE
^2 yK \
WNl/ /
/\ \ 3fNE
Sw /
y&f^~ \
wsw\
sw^
// NJ2/
\J6 /
/*\ / /ese
\ v/^E
ALL WIND SF
EEDS
\20 /
ssw ""— —
SSE
PERIOD
YEARS 1955-1964
FREQUENCY OF OCCURRENCE {%)
ANNUAL WIND ROSE
SITE:
UKIAH
hlU^-"^~
A\20
nu/ J><r '
7"%? /
\nE
WNl/ / y*\ \~—
\ 3ene
~~M./ \^*^\
WSw\ \ yv /
/ese
NC \J6 /
Sw\ ^^^
/SE
\2e /
SSW
ALL WIND SPEEDS
STABILITY CLASS 1
5 ' SSE
PERIOD
YEARS 1955-1964
FREQUENCY OF OCCURRENCE (%)
ANNUAL WIND ROSE
SITE:
UKIAH
NNW--- "
~\NNE
\nE
NiK
^/^v
7^1 /^
WNl/ / /C \-_
rLf v-^X
\ J^NE
u
w
sw\
yW
/ /ese
\y \j6 /
Sw\ ^^^
/SE
\26 /
SSW '
S SSE
ALL WIND SPEEDS
STABILITY CLASS 2
PERIOD
YEARS 1955-1964
FREQUENCY OF OCCURRENCE (%)
ANNUAL WIND ROSE
SITE:
UKIAH
NNU^-^^"
ogNE
/Sje
\nE
Nix
y^6
"""""/^ /
WNl/
\fii/ \^-^\
\ 3ene
\ ^\^ /vj/ '
WSw\ \ /Nog/
/ /ese
\X \J6 /
SwV 7^^_
/s£
\?0 /
ssw "
5 ^SSE
ALL WIND SPEEDS
STABILITY CLASS 3
PERIOD
Figure 4.5-7
Stability Wind Roses for Ukiah, California
211
4.6
MIXING HEIGHTS AND INVERSIONS
The entire atmosphere, is not available for the dilution
of pollutants released near the surface. Only the mixing layer
which, in many situations may be only several hundred feet thick,
can serve this function. Section 4.2.3 describes mixing heights
and inversions in considerable detail relative to their role in
dispersion meteorology.
I This section shall investigate the characteristics of
the mean mixing layer throughout various areas of the Ukiah
District. In addition, inversion statistics will be presented
for various locations in the study area, and the subsequent dis-
cussions shall provide a review of inversion types and their
frequency in the Ukiah District.
4.6.1
Mixing Height
Considerable variation in mean mixing heights occurs on
a seasonal basis. Throughout the United States, mixing heights
vary from several hundred feet on winter mornings to well over
13,000 feet on summer afternoons. In California, the mean annual
range is roughly between several hundred feet and approximately
10,000 feet. The variation in mixing heights over a given area
can play a major role in pollutant dispersion for certain types
of sources. For example, power plant siting is very dependent on
regional dispersion characteristics. An area with a history of
shallow or low mixing heights would tend to trap pollutants
emitted by such a facility. Such an area would therefore be
rated as unfavorable for power plant siting.
Mixing depths can be characterized for each air basin in
the district using data prepared by Holzworth (1972). Annual
morning mixing heights within the Ukiah District generally range
from 500 meters along the coast to less than 400 meters in por-
tions of the Sacramento Valley. During the afternoons, mixing
heights remain at about 500 meters along the coast on an annual
basis and decrease with inland progression toward the Sacramento
Valley. Seasonally, morning mixing heights tend to be most
restrictive during summer and fall with mixing heights decreasing
from around 500 meters along the coast to nearly 300 meters in
the Sacramento Valley. Mixing heights are greatest during the
spring months when morning values reach 800 meters along the
coast and 600 meters in the Sacramento Valley. During the after-
noon hours, annual mixing heights increase with progression from
the coastline ranging from around 800 meters to over 1200 meters
in:the Sacramento Valley. Seasonally, spring is again the best
season with mixing heights ranging from 1200 meter along the
coast to over 1600 meters in the Sacramento Valley. A ^jery steep
gradient in afternoon mixing heights exist during the summer and
fall afternoons. In summer, mixing heights range from £00 meters
near the coast to 1600 meters in the Sacramento Valley. This
212
reflects a situation where a marine air at coastal stations
results in a very shallow stable layer while inland surface
heating effects tend to erode the stable layer near the surface
and result in ample mixing heights.
The CARB (1974) has conducted upper air observations for
winds and temperatures aloft at Sacramento, Red Bluff, Salinas,
Fresno, Ukiah, Thermal and Riverside. The length of the data
base presented in this report is less than three years in every
case. The Ukiah data provide additional information relative to
mixing height characteristics in the Ukiah District. Figures
4.6-1 and 4.6-2 provide a comparison of the mean spring morning
mixing heights as defined using CARB and Holzworth data, respec-
tively. Additional data from Sacramento, Red Bluff and Ukiah
provide very useful additional information for the Ukiah Dis-
trict. The Holzworth data which, once again, was based on a very
limited availability of upper air data indicates a linear de-
crease of mixing heights on spring mornings from 800 meters along
the coast to around 600 meters at Sacramento and Red Bluff. The
ARB data, however, indicates that this is not indicative of
conditions in this area. The ARB data indicates that mixing
heights are on the order of 400 meters along the coastline of
Mendocino County decreasing to 300 meters in the Sacramento
Valley portion of the Ukiah District. Higher mixing heights are
observed in the San Francisco Bay region. The CARB data provide
a better resolution in the Ukiah District as they are based upon
the use of available data from Ukiah, Sacramento and Red Bluff.
The data are only available for the morning hours and conclusions
cannot readily be made relative to the utility of the Holzworth
data for the afternoon. In addition, the additional resolution
provided by the CARB data is only valid for the southern portion
of the district and does not provide additional clarification
relative to northern portions of the district. The CARB data
provides the following highlights relative to morning mixing
heights in appropriate portions of the district:
(1) The lowest average
summer at Red Bl uf f ,
mixing heights occur
Ukiah and Sacramento.
during the
(2) During other seasons,
are unremar kabl e .
mixing heights at these locations
(3) Highest average mixing heights occur at Ukiah
and Sacramento during winter.
Red Bluff
Table 4.6-1 provides seasonal and annual mean morning
and afternoon mixing height values for selected stations through-
out the Ukiah District. It is evident from these data that
mixing heights tend to be higher along the coast during the
morning hours and in the interior valleys during the afternoon.
Long-term mixing height and inversion data are not
currently available for the mountain areas. As a result, inter-
polative estimates must be made from meteorological data from
nearby locations in order to provide a reasonable evaluation of
mixing height levels over mountainous terrain.
213
Figure 4.6-1
Isopleths of Mean Spring Morning
Mixing Heights (m) (with ARB Data)
214
800 6 00
700 50 0
8 0 0 700
60 0 5 0 0
Figure 4.6-2
Isopleths of Mean Spring Morning
Mixing Heights (m) (from Holzworth)
215
Table 4.6-1
Mean Morning and Afternoon Values of
Mixing Height (Meters)* in the Ukiah District
Morni ng/Af ternoon
Winter
Spring
Summer Fall
Annual
Eureka
500
780
500 480
565
800
1150
700 850
875
Santa Rosa
430
300
700
1 24"0
465 425
800 960
504
950
1 2
Ukiah '»*
487
369
286 434
394
800
1320
900 1000
1005
1 2
Sacramento '
300
282
223 2^9
263
950
1900
1700 1400
1488
* meter = 3.28 feet
Mixing heights determined from interpolation of seasonal mixing
height analysis from Holzworth's "Mixing Heights, Wind Speed,
and Potential for Urban Air Pollution Throughout the Continguous
United States".
Morning mixing heights based on Air Resources Board data covering
a five year period from July 1, 1972 to December 31, 1977.
216
The steepness of windward mountain slopes and numerous
meteorological parameters such as wind velocity, wind direction
and atmospheric stability impact mixing height depths and their
variability over rugged complex terrain. Figures 4.6-3 through
4.6-5 illustrate mixing layer alterations due to mountain flow
for three hypothetical scenarios which vary atmospheric stabili-
ty. As depicted in Figure 4.6-3, when the lower atmosphere is
neutrally stratified, the inversion layer, which is the major
determinant of the local mixing depth, tends to follow the con-
tour of the local terrain. Hence, mixing height depths, as
defined earlier, remain unchanged or tend to be slightly shallow-
er over the mountainous area.
On the other hand, when a stable surface air mass is
capped by an elevated inversion and is forced to rise over abrupt
mountainous terrain, considerable variations in the characteris-
tic mixing depth develop. The low lying, stable air is not
easily displaced upward and over the mountain ridge; consequent-
ly, the surface air mass tends to pile up along the windward
mountain slopes, thus forming a bulge in the atmospheric mixing
layer just upwind of the mountain ridge. Under these conditions,
as depicted in Figure 4.6-4, the mixing depth tends to be larger
along the windward slope than along the valley floor or the
leeward side of the mountain range.
Figure 4.6-5 presents the situation in which a sur
unstable layer is isolated from the upper atmosphere by a li
inversion. As flow moves over rugged terrain, dramatic cha
in the mixing layer can occur. Basically, the low lying,
stable air is forced to ascend into and through the inhibi
inversion layer as surface air flow is swept up the steep wes
the Coast Ranges. This forced convective acti
has the potential to completely wipe out the 1
layer (or considerably weaken the stable layers)
considerable mixing of the lower lying air mas
conditions, considerable cloudiness can develop
si opes of
somet i mes
inversion
promot i ng
Under such
at times, much precipitation. This is indicative of su
season conditions resulting in convective thundershower activ
As the flow passes over the mountain ridge and descends down
leeward slopes, the stable layer can once again develop.
face
fted
nges
un-
ting
tern
vity
oca!
thus
ses .
and ,
mmer
i ty .
the
The above discussion qualitatively depicts mean mixing
height characteristics when flow is forced over mountainous
terrain features such as the Coast Ranges. However, definitive
analyses are needed to support the qualitative review presented
for this area. Therefore, estimates and assessments of mixing
layer depths over these areas are presently best determined by
(1) the Holzworth document entitled: "Mixing Heights, Wind
Speeds, and Potential for Urban Air Pollution Throughout the
Contiguous United States" and (2) the CARB data summarized in
"Meteorological Parameters for Estimating the Potential for Air
Pollution in California." Seasonal and annual mixing depth
contour maps provided by the Holzworth publication are depicted
217
E-3
0
$
&
<■<!£
TOP
? INVERSION .$^Vr> J^^ ^^
FLAYER fe@^Svfe§^
BASE
NEUTRAL
vwwv^r
**S*§3&5&«W<*
^xTT^T^T^^r
Figure 4.6-3
Depth of the Mixing Layer in Mountainous Terrain with Neutral Flow
E-4
TOP
BASE
•^STRONG "'/-'-v. — V < V-"^
3 INVERSION «LV ^-S"
STABLE
£*>-
AVsWVWA
Figure 4.6-4
Depth of the Mixing Layer in Mountainous Terrain with Stable Flow
E-5
TOP *&s^-?3£gk&$2&Mj
.« INVERSION
?, ST AB LE LA YE R \St}.
BASE *ET*"
UNSTABLE
ZONE OF
FORCED ATM
CONVECTION
WARMER BUT
UNSTABLE TO NEUTRAL
Figure 4.6-5
Depth of the Mixing Layer in Mountainous Terrain with Unstable Flow
218
in Appendix C. These figures
comparing California mixing
areas of the United States.
also present an excellent means for
depth characteristics with other
4.6.2
Inversion Types and Frequencies
The type and frequency of temperature
an important role in the overall description
dispersion meteorology of the Ukiah District.
si.ons are either surface based or elevated with
on potential pollutant sources. Surface based
in a layer of stable air close to the ground
inversions plays
of the regional
Basically, inver-
differing impacts
inversions result
usually with very
light wind speeds. This type of situation tends to maximize the
impact of ground level non-buoyant sources such as vehicles (e.g.
off road vehicles [ORV]) and fugitive sources (e.g. storage
tanks, dirt roads, etc). Elevated inversions tend to limit the
volume of air available for the mixing of pollutants and tend to
maximize the impact of buoyant elevated sources, such as power
facilities, refineries, etc. The following paragraphs provide a
review of the type and frequency of inversions experienced in the
Ukiah District.
As indicated earlier, upper air data are only routinely
available for Oakland, California. These data have been sup-
plemented by special studies conducted largely by the CARB at
Ukiah in the Ukiah District.
Table 4.6-2 summarizes the available historical inver-
sion data for the Ukiah District. These data include soundings
taken at Areata, Eureka, Ukiah and Sacramento. With the excep-
tion of a brief period of record available from Areata, all the
data are representative of the early morning hours. The data
indicate the very high frequency of surface inversions, particu-
larly at Ukiah and Sacramento. The frequency of times when there
were no inversions present is quite rare with the exception of
Areata. At Areata, no inversions existed during a substantial
number of soundings. While the period of record is brief at
Areata, this does point to the fact that dispersion conditions
near the surface tend to be somewhat less restrictive along the
well exposed northern coast of the Ukiah District where the
influx of maritime air tends to be accompanied by brisk winds and
reasonable mixing heights. At valley locations, such as Ukiah
and Sacramento, conditions tend to be more restrictive, particu-
larly during the fall and summer periods. These data are further
summarized in Figures 4.6-6 and 4.6-7.
219
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4.7
TYPICAL AND WORST-CASE CONDITIONS
Previous sections have thoroughly examined and discussed
the factors affecting the atmospheric dispersion characteristics
of the Ukiah District. This permits the identification of typi-
cal and worst-case conditions for a variety of typical sources
found in the Ukiah District. This analysis will provide a basis
for determining an initial evaluation of the typical and worst-
case impact of various land use alternatives using simplistic
modeling techniques as described in Section 4.9.
4.7.1
Typical Dispersion Conditions
Typical dispersion conditions define the most commonly
occurring combination of the key dispersion parameters, i.e.,
wind speed, wind direction and atmospheric stability class. This
information is useful particularly in first cut or screening
level of effort air quality modeling analyses as described in
Section 4.9. In such cases, it is desirable to have a rough
estimate of the most commonly occurring dispersion conditions in
order to get an indication of the typical impact of an existing
or proposed source.
Table 4.7-1 provides a description of the most frequent-
ly occurring dispersion parameters for sites in the Ukiah Dis-
trict for which the necessary data are available. These include
Ukiah, Areata and Sacramento.
The data in Table 4.7-1 provide the most frequently
occurring wind direction, wind speed and stability category
information suitable for characterizing dispersion meteorological
conditions. As such, it is suitable for use in screening level
of effort or simplistic modeling calculations to provide a pre-
liminary estimate of existing or proposed pollutant source im-
pacts. The reader is cautioned, however, that dispersion analy-
ses require site specific meteorological data and a more thorough
review than that provided by the type of information contained in
the table .
4.7.2
Worst-Case Dispersion Conditions
Worst-case dispersion conditions are used by dispersion
meteorologists in a screening level of effort to determine the
probable maximum impact of an existing or proposed facility. The
results of such a review provide an indication as to whether more
detailed and sophisticated analyses are required. Once again, as
with typical conditions, the worst-case can be defined in terms
of the primary dispersion parameters, atmospheric stability
class, wind speed and wind direction. The reader is again cau-
tioned in the use of the following information as s i t e- spec i f i c
data and more detailed analyses are desireable to accurately gage
pollutant impact.
223
Table 4.7-1
Description of Typical Meteorological Conditions * '
Throughout the Ukiah District
Wind
Wind
Stability
Station
Direction
Speed (MPH)
Category (2)
Sacramento
SSW
7.5
3
Ukiah
SSE
3.6
3
Areata
E
6.8
2
1. As defined by the most frequently occurring value on an annual basis -
parameters are not interrelated, i.e., the indicated wind speed is for
the total data base and is not the average for the most frequently
occurring wind direction.
2. 1 - Unstable (Pasquill Classes A, B, C)
2 - Neutral (Pasquill Class D)
3 - Stable (Pasquill Classes E, F, G)
224
In an effort to identify the historical worst-case
conditions occurring in California, it was necessary to create a
table of five pollutant sources with typical exit characteris-
tics. Table 5.4-1 summarizes typical emission characteristics
for fugitive dust, automobiles, oil recovery operations, oil
refineries and large power plants. In addition, a traditional
worst-case scenario often used by dispersion meteorologists is
described. Although the primary pollutants generated from each
of these sources may vary, the short-term characteristics of
these gases and/or particulates in the atmosphere may be assumed
to be highly similar. The five sources listed in Table 5.4-1
represent ground level, non-buoyant; ground level, slightly
buoyant; low-level, buoyant; i nt ermed i ate- 1 ev el , buoyant; and
elevated, buoyant emissions, respectively. Table 4.7-2 lists the
worst-case dispersion conditions for each of these sources.
Table 4.7-3 provides the annual frequency of the se-
lected worst-case scenarios for stations throughout the Ukiah
District. The table indicates that the selected scenarios for
the cross section of sources occur with considerable variability
across the area. In addition, the frequency of the scenario
selected for one type of source may occur with a substantially
different frequency than that selected for another source. This
highlights the importance of attaching the probability of occur-
rence to the selected worst-case meteorological condition for the
source in question and the need to involve professional disper-
sion meteorologists in such programs.
Mixing height, an important parameter in the definition
of both typical and worst-case conditions has not been included
in the above analysis. This is often difficult to do as real
time mixing height data are not generally available concurrently
with surface wind speed, wind direction and atmospheric stability
class data to provide for meaningful analysis. However, typical
mixing heights can be obtained from the data presented in Section
4.6.1, while historical worst-case mixing heights are discussed
by Holzworth in his publication "Meteorological Episodes of
Slowest Dilution in Contiguous United States".
225
Table 4.7-2
Worst-Case Dispersion Conditions
For a Cross-Section of Typical Sources
-c 0)
•Source
Wind Speed
(MPH)
Stability Class ,,,>
(Pasquill Class)Uj
Fugitive Dust
1.1
D
Automobiles
1.1
D
Oil Recovery Operations
26.8
C
Oil Refinery
6.7
A
Power Plant
6.7
A
(3)
Traditional 'Worst-Case
2.3
F
1. Reference Table 5.4-1 for a description of the exit characteristics
for the sources listed below.
2. Section 4.5 provides a complete discussion of atmospheric stability
3. In theoretical or "back of the envelope" calculations, this case is
often used by meteorologists to describe worst-case conditions.
226
Table 4.7-3
Annual Frequency (%) of Worst-Case Meteorological Conditions * '
Throughout the Ukiah District
Worst-Cast Condition
(St. Class/Wind Speed(MPH)
Areata
Ukiah
Sacramento
F and 2.3
10.0
36.0
13.9
D and 1.1
13.0
9.4
2.9
C and 26.8
Neg.+
0.0
Neg.+
A and 6.7
0.2
0.8
0.6
1. As defined for the sources indicated in Table 4.7-2
and described in Table 5.4-1
+ Neg. = Negligible but non-zero
227
4.8
AIR BASIN ANALYSIS
The State of California encompasses an extremely large
land area which exhibits a wide variety of geographic and topo-
graphic features (see Section 2). As air masses migrate into
California, the prevailing winds and dispersion characteristics
are greatly influenced by terrain. The degree and nature of the
influence can be characterized for geographically and/or meteor-
ologically homogeneous areas. Such zones of similar atmospheric
dispersion characteristics can be identified as air basins.
Figure 4.8-1 provides the results of an air basin analysis for
California while Figure 4.8-2 presents a summary map of the air
basins located within the Ukiah District of California. The
figures represent an original analysis independent of political
boundaries and are, therefore, slightly different than the CARB
air basin map for the State. The latter figure is also provided
as Overlay F.
Air basins provide a means of isolating particular areas
of the state that generally exhibit similar atmospheric flow,
ventilation mechanisms and dispersion potential. As presented in
the figure, these areas include:
North Coastal Air Basin
North Coastal Mountain Air Basin
North East Hills Ai r Basi n
Mountain Area Air Basin
Sacramento Valley Air Basin
San Joaquin Valley Air Basin
San Francisco Bay Area Air Basin
Central Coast Air Basin
Central Coastal Mountains Air Basin
South Coastal Air Basin
South Coastal Mountains Air Basin
Great Basin Valley Air Basin
South East Desert Air Basin
The development and use of an air basin classification
scheme requires one to visualize the atmosphere as a moving fluid
washing over mountain ridges and spilling into valleys and
through canyon areas. As indicated above, physically and meteor-
ologically homogeneous areas can be then identified and used in
dispersion analyses. Regional terrain characteristics generally
establish the boundaries of such areas. Terrain features are
dominant in establishing air basins as mountain ranges and val-
leys obstruct or alter regional flow and, hence, dispersion
co-nditions. Figure 4.8-1 illustrates the importance of terrain
fe.atures in defining meaningful air basins.
While air basins are characteristically defined by major
regional terrain features, the climatological and -dispersion
meteorological conditions existing in the area in question also
provide considerable information relative to the identification
of homogeneous air basins. An area can be homogeneous from a
228
"~| NORTH COASTAL
«|J NORTH COASTAL MOUNTAINS
NORTH EAST HILLS
SACRAMENTO VALLEY
SAN FRANSCISCO BAY AREA
Vj SAN JOAQUIN VALLEY
||5£j5j CENTRAL COAST
^ CENTRAL COASTAL MOUNTAINS
MOUNTAIN AREA
GREAT BASIN VALLEY
SOUTH EAST DESERT
| SOUTH COASTAL MOUNTAINS
SOUTH COASTAL
Figure 4.8-1
California Air Basins
229
terrain standpoint but may vary s i gni f i cant 1 1 y in terms of the
actual dispersion meteorology. For example, in California, a
case could be made for including the Moj ave Desert and Owens
Valley into one air basin as defined by the terrain characteris-
tics of this general region. However, it is known that the
dispersion meteorology is considerably different in the lee of
the Sierra Nevada in the Owens Valley as opposed to that experi-
enced in the Mojave Desert. As a result, the Great Basin Valley
has been delineated as a separate entity from the South East
Dessert air basin. Substantially different dispersion meteoro-
logical characteristics, such as important differences in pre-
vailing winds, wind speed, atmospheric stability, and mixing
heights dictated this decision in the absence of important ter-
rain considerations.
An air basin analysis provides considerable insight into
the potential impact of air pollutant emissions within certain
regional areas. Particular air basins may ventilate air pollut-
ants very slowly while others do so quite quickly. A detailed
discussion of the dispersion characteristics for each air basin
in the Ukiah District follows.
The Ukiah District includes portions of 4 of the 13
California air basins as depicted in Figure 4.8-2. They include:
• North Coastal
• North Coastal Mountains
• Sacramento Va 1 1 ey
• San Francisco Bay Area
The North Coastal Air Basin comprises the bulk of the
Ukiah District in Mendocino, Humboldt, and Del Norte Counties.
The air basin is generally comprised by good ventilation poten-
tial with strong onshore winds. Except for the immediate coast-
line, the area is one of fairly rugged terrain and ventilation is
further enhanced by surface roughness induced mixing effects.
Air quality in this region tends to be good, reflecting a strong
maritime influence and good ventilation potential. The ventila-
tion potential is particularly good during the rainy season when
the frequent passage of migratory storm systems results in strong
winds, active weather and excellent dispersion. Poorest disper-
sion generally occurs during late summer and early fall when wind
speeds become lighter and marine inversions are fairly shallow
an.d restrictive. However, air quality is still generally good in
this region in the absence of important air pollutant sources.
The North Coastal Mountains Air Basin comprises the Lake
County and Northern Napa County portions of the Ukiah District as
well as a small portion of eastern Mendocino County. The area is
characterized by fairly rugged terrain with several inland
230
RAFAEL f U
Figure 4.8-2
Air Basins in the Ukiah District
231
valleys. The maritime influence in the Pacific Ocean tends to be
decreased at this location and the ventilation potential is
slightly poorer. Ukiah, for example, experiences fairly light
wind speeds during many occasions and in summer and fall the
mixing heights tend to be fairly restrictive. Under such condi-
tions, the potential for pollutant buildup does exist. The
ventilation potential is excellent at higher elevations within
this air basin, however, the potential is very poor at sheltered
valley sites. This area is an active geothermal region and
considerable studies have been conducted relative to the pollu-
tion potential of Lake County.
Colusa, Yolo and Solano Counties are located within the
Sacramento Air Basin. Ventilation potential in this region tends
to improve as one moves northward. The area is subject to the
maritime influence of Pacific Air moving into the Carquinez
Straits and diverging both north and south into the Sacramento
and San Joaquin Valleys, respectively. The ventilation potential
can be restricted, particularly during the fall and winter months
when winds are light and mixing heights are shallow. Under such
conditions, fog and low clouds can develop and persist for days
with the concomitant potential for a significant buildup of
pollutants. During the summer season, wind speeds tend to be
strong and the maritime influence of Pacific air moving into the
region tends to inhibit significant pollutant buildups.
Finally, the San Francisco Bay Area has been isolated as
a separate air basin. Marine flow from the west and west-north-
west is channeled directly inland over the San Francisco area.
As marine flow enters the area, it is channelled along the two
major axes of the San Paolo and San Francisco Bays. The San
Paolo Bay loops eastward through the Carquinez Straits into the
San Joaquin Valley while the San Francisco Bay points southeast-
ward into the Santa Clara Valley. It is also noted that marine
air tends to turn northwestward and northward into the Santa Rosa
area and further to the north, Ukiah. Ventilation potential can
become restricted in these inland valleys north of the San Fran-
cisco Bay region.
4.9
FIRE WEATHER
The primary purpose for the utilization of open burning
is to quickly eliminate choking underbrush, for example, in the
management of forested lands, or to dispose of waste vegetative
growth in the management of agricultural areas. These goals must
be accomplished while causing a minimum impact upon ambient air
qu-ality in the surrounding region. For this reason, it is desir-
able to achieve a quick, hot burn which will result in a minimum
burn time, while maximizing the atmosphere's dispersive capabil-
ities by getting the resulting smoke well above the surface
1 ayer .
232
Meteorology plays a very important role in the identifi-
cation of proper periods during which to burn with a minimum
impact on surrounding air quality. Burn versus no-burn days are
forecasted daily by the CARB for each of the designated air
basins in California. Forecasts for the following day are usu-
ally available by 1500 PST. If the issuance of a forecast is
delayed, they are to be available by no later than 0745 PST on
the day in question. The CARB uses some very basic criteria in
making decisions relative to open burning in each of California's
air basins. The forecasting criteria are designed to isolate
those days on which the burning of large surface areas will have
a minimum impact on local air quality, based upon the atmos-
phere's ability to disperse pollutants. Factors which impact
this are the stability of the atmosphere, the presence of either
surface or elevated inversions and the mean wind speed and wind
direction. Previous sections have provided a review of the
dispersion meteorology of the Ukiah District and reference is
made to that discussion for more details relative to these para-
meters .
The dispersion of smoke generated from open burning is
restricted by such features as stable atmospheric conditions, an
elevated inversion which restricts the volume of air available
for mixing, as well as low wind speeds which result in little
movement of the pollutants once they are emitted. These mete-
orological considerations work hand in hand with the nature of
the local terrain. Areas which are in a valley or a bowl and are
surrounded by important terrain features tend to trap emitted
pollutants near the source particularly when restrictive meteor-
ological conditions combine with such terrain effects. Accord-
1 n 9 1 y > the CARB forecasting criteria include a review of the
anticipated strength of the morning surface inversion, the rela-
tive stability of the atmosphere from the surface to roughly
3,000 feet, the wind speed at the expected plume height, as well
as the probable wind direction. Burning is not permitted on days
when wind speeds are light, the atmosphere is stable, strong
surface or elevated inversions exist, or if wind directions will
tend to blow smoke toward populated areas.
Section 6.5.2 will provide a review of the regulatory
constraints involved in open outdoor burning including the acqui-
sition of permits. Once a permit is obtained, the basic decision
whether or not to burn is based upon acquiring the burn/no-burn
forecast from the CARB in Sacramento. In addition to this, local
rules of thumb should be used to provide proper management of the
burn in terms of meteorological conditions. The following pro-
vides an example of typical considerations:
• The wind direction at the probable plume height
should be such that the plume will move away from
Smoke Sensitive Areas (SSA). The California Divi-
sion of Forestry (CDF) has designated SSA's in
California which should not be impacted by any burn
233
contemplated by BLM managers. Figure 4.9-1 pro-
vides a review of the location of such areas in the
state. These regions include most of the populous
areas of the state, as well as areas in rugged
terrain subject to considerable recreational use.
Low wind speeds should be
where SSA's may be impacted.
avoided, particularly
Wind speeds should generally be greater
miles per hour to maximize dispersion.
than 15
Surface inversions should be avoided due to the
potential for trapping the smoke near the surface.
However, if the plume is carried above the inver-
sion, the downward dispersion of contaminants will
be inhibited by the surface based inversion.
If the burn will be less than 12 hours, it is
beneficial to start in the morning as this will
tend to maximize the buoyant effects associated
with the burn.
If the burn is to last more than 12 hours, it may
be beneficial to start at night as this may mini-
mize adverse smouldering effects, experienced
following the burn.
Burning in precipitation is advantageous from an
air quality viewpoint as much of the contaminants
will tend to be washed out of the plume.
Burning should not be conducted when visibility is
less than 11 miles at the site or at a nearby SSA.
Burning should never be conducted when fire danger
exists and the manager should be cognizant of
forest fire weather forecasts provided by the NWS.
The manager should be able to respond to deteri-
orating conditions so that the burn can be down-
graded should dispersion conditions become poor.
Unlimited burning is never recommended unless the
wind direction is away from a SSA, or a SSA is
located more than 100 miles away, or if the burn is
to be conducted during precipitation. Even in
these instances, a quota should be established for
the amount of dry fuel to be burned during the day.
Burning should not be conducted when- the wind
direction will result in the movement toward a SSA
if the area is within 30 miles.
234
"7"
SUSANVILLE
DISTRICT
UKIAH
DISTRICT
CALIFORNIA AIR BASINS
SCALE IN MILES
100
FOLSOM
DISTRICT
BAKERSFIELD
DISTRICT
I
FOREST SERVICE DESIGNATED
SMOKE SENSITIVE AREAS
L^
SMOKE SENSITIVE AREAS
RIVERSIDE
DISTRICT
Figure 4.9-1
235
Figures 4.9-2 and 4.9-3 provide a review of typical
atmospheric conditions experienced over California during the
afternoon and nighttime hours. Figure 4.9-2 displays the terrain
of California, including the Coast Range, the Sacramento Valley
and the Sierra Nevada. As indicated in the figure, the prevail-
ing wind in this area is from west to east. The atmosphere,
close to land areas tends to be unstable during the afternoon
hours, while over the ocean and above the unstable air, a \/ery
stable regime exists as part of the marine layer induced by the
nearby ocean. This generally extends up to nearly a thousand
feet during the afternoon. Above that point, the atmosphere is
generally slightly stable. Three potential burns are illustrated
on the figure; one in the Coast Range, one near the Coast Range,
and one in the Sierra Nevada. In addition, the figure depicts a
SSA in the populous Sacramento Valley region.
Coast
to the east
an unstabl e
that of the
not have an
The fire
Range woul d
illustrated in the higher elevations of the
have a very limited impact in the SSA located
The plume is initially buoyant and is emitted into
atmosphere and will tend to reach an elevation above
stable layer. As such, in most instances, it will
important impact on the SSA as downward dispersion
will be inhibited. The burn illustrated in the lee of the Coast
Range at a relatively low elevation would have to be managed very
carefully as it is in relatively close proximity to the SSA.
Here, the plume is emitted into an unstable atmosphere, but is
limited from continued dispersion aloft by the presence of a very
stable elevated inversion. As such, the plume does have the
potential to impact the SSA and would have to be regulated very
closely. The final burn indicated in the figure is well up into
the Sierra at a location where it should have an acceptable
impact on local air quality. The plume is moving away from the
SSA and is benefiting from excellent dispersion effects due to
the unstable surface layer as well as the effects imparted by
orographic lifting over the higher terrain.
Typical meteorological conditions in California at night
are displayed in Figure 4.9-3. In this instance, very stable air
tends to accumulate over the SSA, and burning would not be recom-
mended in the zone. Burning at mountaintop locations, however,
would still be acceptable as they are being emitted into a
slightly stable atmosphere and the very stable layer below would
prohibit the downward dispersion of the plume into the SSA.
These figures provide only idealized descriptions of typical
meteorological effects on potential burn situations. It is
emphasized that the decision should be based upon burn/no-burn
forecasts available from the CARB, even in areas which are out-
side the jurisdiction of regulatory agencies due to elevation as
described in Section 6.5.2.
236
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4.10
GENERAL DISPERSION MODELING
Dispersion modeling is a mathematical representation or
simulation of transport processes that occur in the atmosphere.
There are numerous dispersion modeling techniques available, all
of which aim to calculate ground level concentrations of pol-
lutants that result from industrial, agricultural, transportation
and urban emissions. It is important to realize that there
exi-sts no single modeling technique capable of properly depicting
all conceivable dispersion situations that occur in the atmos-
phere. Likewise, meteorological conditions impacting dispersion
are complex and depend on the interaction of numerous physical
processes. Therefore, any successful modeling effort must be
directed by individuals with broad knowledge and experience in
air pollution meteorology, as well as expertise in data proces-
sing techniques. The judgement of well trained professional
analysts is essential to properly evaluate the ground level
impact of pollutant emissions. Without detailed validation/-
calibration efforts, air quality modeling results are generally
felt to be good only within an order of magnitude under many
circumstances, such as applications in areas of rugged terrain.
Air quality models have been widely used to identify
potential violations of National Ambient Air Quality Standards
(NAAQS). Modeling studies of the atmosphere are useful in deter-
mining emission limits for industrial development in specified
areas. Hence, dispersion models are vital to the timely and cost
effective development of air pollution .ontrol strategies for
most regions. Ideally, mathematical modeling of the dispersion
potential of the atmosphere would allow optimum planning for
proposed land use development in terms of minimizing the air
pollution impact. Dispersion models provide a technique which
can be used to help ensure attainment and maintenance of air
quality standards and to prevent significant air quality deter-
ioration due to future development.
This section is designed to present a basic understand-
ing of dispersion modeling approaches to air qualtiy problems.
The subsections to follow will alllow the reader to understand
the concepts of mathematical air quality modeling. Numerous
models are described as well as techniques for selecting the
optimum approach. English units, which have been employed in
previous sections of this document, will not be used here.
Calculations must be performed in metric units, as dictated by
the equations and figures commonly used in dispersion modeling.
English conversions, however, have been placed on figures as a
convenient reference for the reader.
4. 10. 1 Classes of Model s
Basically,
model s available,
acteri zed as :
there are four general types of air quality
These types of dispersion models are char-
239
• Gauss i an
• Numeri ca 1
• Statistical
• Physi cal
or Empirical
Within each of these classes, there exists a large
number of individual computational algorithms, each with its own
specific application. For example, numerous air quality models
have been developed based upon the Gaussian or log-normal solu-
tion to the fluid transport equation. Each particular model or
algorithm is designed to handle a specific air quality and atmos-
pheric scenario while computing pollution impacts through the use
of the Gaussian diffussion equation. The models may, for ex-
ample, consider different atmospheric parameters, terrain fea-
tures, and various degrees of data resolution. The well-known
EPA dispersion models such as the CI imatol ogi cal Dispersion Model
(CDM), the Air Quality Display Model (AQDM) , the Valley Model,
and the Texas CI imatol ogi cal Model (TCM) are commonly referred to
as individual models but in fact are all variations of the basic
Gaussian model. In many cases, the only real difference between
models is the degree of detail considered in the input and output
of data .
Gaussian models are considered to be the state of the
art technique for estimating the impact of non-reactive pollut-
ants. These types of models assume instantaneous transport of
effluents downwind of the emission source. However, numerical
models are more appropriate than Gaussian models for source
applications which involve reactive pollutants. Most numerical
models employ numerous interactive steps allowing for downwind
adjustments to time dependent chemical and thermal processes that
take place in the plume. Statistical or empirical techniques are
frequently employed in situations where an incomplete scientific
understanding of the physical and chemical processes of the plume
behavior makes the use of the Gaussian and numerical modeling
approaches impractical. Physical modeling, the fourth generic
type, involves the use of a wind tunnel or other fluid modeling
facilities necessary to investigate dispersion in very confined,
specialized environments isolated to only a few square kilo-
meters. Physical modeling is a complex process which requires a
high level of technical expertise.
4.10.2 Model Suitability and Application
The level of analysis for which a particular dispersion
model is well suited depends on several factors. These include:
• The detail and accuracy of the data base (i.e.,
emission inventory, baseline air quality and mete-
orologicaldata)
• The local topographic and meteorological complexi-
t i es
• The technical competence of the individuals direct-
ing the modeling effort
240
• Available financial and computational resources
Air quality models require a data base which includes
emission source characteristics, meteorological parameters and
baseline air quality levels (and at times, local topographic data
and temporal statistics). Models that require detailed and
precise input data should not be applied when such data are
una vai 1 abl e .
Most dispersion models are intended for use only in
areas of relatively simple
ses for major topographic
scenarios may start with
analyses using the Gaussian
define the level of impact
topography. Specific modeling analy-
features and complex meteorological
a simplistic preliminary screening
or other straightforward approach to
If these analyses point to a po-
tentially important impact then more sophisticated modeling
approaches must be implemented.
various levels of
general techniques
t i ve estimates of
source category,
understanding of
Applications of the various classes of air quality
models previously mentioned require a two step approach with
sophistication. The first level consists of
that provide relatively simple and conserva-
air quality impact of a specific source or
This initial screening level, provides an
air pollution impact due to a particular
source(s) in the area in question. The major objective at this
stage is to identify potential violations of air quality stan-
dards. This is done by using simple analytical techniques to
isolate areas of projected maximum ground level concentrations
for comparison with the most limiting standards, and is the level
of effort the District Offices should strive to accomplish.
The second level of effort involves the use of analy-
tical techniques which provide a more detailed treatment of
physical and chemical processes once a potential problem has been
identified. This step requires a more detailed and precise data
base which will result in a more accurate estimate of source
impact. At this point, an exhaustive data base specific to the
study area is incorporated into the modeling analysis. For
example, temporal variations in the baseline meteorology, air
quality and emissions data can be input to the model. Emission
inventory data can also be more accurately assessed in terms of
such aspects as temporal variability.
The screening level approach to air quality modeling is
hig-hly recommended in all initial applications of dispersion
models. If a problem is identified, then more sophisticated
analyses are indicated. In any case, a multi-step approach to
modeling is vital in accurately establishing regional air quality
impact. ;
A specific plan of attack is required for each disper-
sion problem that is encountered. It is not the purpose of this
section to recommend specific models for specific air quality
241
impact situations, but rather to provide a foundation or frame-
work in which to approach the basic air quality modeling problem,
which may be used as a screening level to determine if further
anal ysi s is needed .
4.10.3 The Gaussian Model
Gaussian based models are considered to be the state of
the art technique for estimating concentrations of non-reactive
pollutants such as sulfur dioxide and particulate matter for most
point source emissions. Numerous experiments have been conducted
to study the shape of plumes. The publication "Meteorology and
Atomic Energy" lists over twenty experiments, many of which have
been conducted by the Atomic Energy Commission (now ERDA-Energy
Research and Development Administration). In general, most
investigators have been satisfied that a Gaussian distribution is
a good mathematical approximation of plume behavior over time
periods on the order of five minutes to one hour. Figure 4.10-1
illustrates the Gaussian plume distribution in the horizontal and
the vert i cal .
The Gaussian model provides reasonable estimates in flat
or gently rolling terrain. However, Gaussian based models are
extremely inaccurate for air quality impact assessments in areas
comprised of extremely rugged and varying terrain, such as hilly
or mountainous regions. For such situations, statistical or
physical modeling methods are best employed, since the dispersion
potential of the atmosphere can then be characterized by empiri-
cal data obtained by local monitoring programs.
Properly used, a Gaussian model is unequalled as a
practical diffusion modeling tool in terms of simplicity, flexi-
bility and the successful correlation between predicted and
measured values. For these reasons, the Gaussian model is used
in this section to illustrate several simple modeling problems.
All variables which will be used to solve the Gaussian equation
wi 1 1 now be def i ned :
C(x,y,z)
a o
is the concentration at a point (x,y,z).
is the mean
are the standard deviations in the y and z
directions
i s the emi ssi on rate
is the mean wind speed and
is the height of the plume centerline when it
becomes essentially level.
242
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The normal or Gaussian frequency curve is given by:
C (x) =
(2tt) a
exp
(x - x)'
9 2
2o
4.10-1
Where C is the concentration, x,is the mean, and o is the
standard deviation. ( 2tt ) 1^ 2 makes the area under the curve, from
x = _ oo to = + °°, equal to 1 (See Figure 4.10-2).
C(x)
-3o-
2o-
-1(7
R
ler
2a
2%
161
50%
Bui
98*
Figure 4. 10- 2
Gaussian or Log-Normal Distribution
When a distribution is bi normal in the two dimensions x and
y, the probability density function is:
1
exp
C (x,y) =
(x - x)2
2tt a a
x y
(y - y)2
y
4.10-2
If there is a continuous emission, Q, of gas or aerosols
from a point, H, above the ground, a 3 dimensional coordinate
system must be defined so that the origin is on the ground be-
neath the point of emission, x is in the direction of the mean
wind, u, y is crosswind and z is vertical.
Likewise, it is assumed that the diffusion in the crosswind
and vertical dimensions will occur in a Gaussian manner, so that
the pollution will move downwind with the mean speed of the wind,
and that the diffusion in the downwind direction is negligible
compared with the transport.
The concentration, C, at any point (x,y,z) can be written
as
exp -
C (x,
y>
Q
z) u _
1
2tt o o
y z
1
r 2
y
j_
(z - H)2
2
2
0
L y
2
J
4.10-3
Here y is assumed to be 0, and z assumed to be H. In this
equation, C has units of mass per volume; u, velocity or length
per time; Q, mass per time; a and o length; and y,z, and H,
length. y
Because diffusion in the z direction is bounded by the
earth's surface, equation 4.10-3 cannot be strictly used. If it
can be assumed that the ground acts as a perfect reflector,
therefore, source at z = H is assumed to have a virtual "image"
source at z = -H and
C (x, y, z) u
Q
exp
1
2tt oy az
<z - f + ex
2a
P ~
(z + H)
2
2a
exp
2
-y
4.10-4
This is the generalized diffusion equation. We cannot
expect to obtain instantaneous concentrations from this equation,
but concentrations averaged over at least a few minutes time.
There are several reasons to expect this equation to be valid for
the atmosphere. It obeys the equation of continuity, i.e., the
conservation of mass. The mass Q/l second is found between any
two planes perpendicular to the x-axis at a distance u / 1 second
apart. Secondly, diffusion is a random process and the distri-
bution of material from such motion may be expected to be in some
statistical form; in this case, according to the Gaussian curve.
one theoretical reason why one would not expect
apply. Diffusion can only occur at a finite
concentration of released material should drop
distance from the x axis because it has not
point. The Gaussian distribution assumes the
material to be spread from - °o to + °o crosswind. This is not of
practical importance, however, as the Gaussian distribution drops
off extremely rapidly within a few a crosswind. One practical
limitation is that the Gaussian distribution does not allow for
any wind shear in the surface layer.
However , there is
this equat i on to
speed, i.e., the
to zero at some
di f fused to this
ti ons
Interest is
i.e., C ( x ,
generally focused upon ground level concentra-
Y, 0). Substituting z = 0 in (4.10-4) yields:
C(x, y, 0) u _
Q
4.10-5
ti c a
y z
exp
2a
,2 -i
2o
245
1 s
It will be
eliminated in
noted that the 2 in the denominator in (4.10-4)
(4.10-5) because of the 2
resulting from
numerator .
2 exp -
H
2o
occurring in the
If the source is at ground level (H = 0), there is further
simplification. Similarly, if one is interested only in center-
line concentrations (directly downwind) then y = 0, and equation
(4.10-5) may again be simplified.
This (4.10-5) is the basic
ground level concentration from a
usual units for the variables are:
(x, y, 0)
y
y, h,
equation for calculating
continuous point source.
/ 3
gms/m
m/sec
gms/sec
meters
the
The
As seen from Equation 4.10-5, the plume concentration
(C) at various downwind distances (x) from the emission source is
largely dependent upon horizontal and vertical dispersion coeffi-
cients (sigma y or sigma z). Figure 4.10-1 illustrates the
coordinate system for a typical plume and visually describes the
significance of the dispersion coefficients in the y and z
directions.
Stability
The values of both oy and oz will depend upon the turbu-
lent structure of the atmosphere. If measures of horizontal and
vertical motions of the air are made as with a bivane, the re-
sulting records may be used to estimate a and oz
quill, 1961). If wind fluctuation measurements are
( see Pas-
not avail-
able, estimates of °y and °z may be made by first estimating the
stability of the atmosphere from wind measurements at the stan-
dard height of 10 meters, and estimates of net radiation (Pas-
quill, 1951). Stability categories (in six classes) are given in
Table 4.10-1 in terms of insolation during daytime (radiation
received from the sun) and amount of cloud cover at night.
Strong insolation corresponds to a solar altitude (above the
horizon) greater than 60 with clear skies, and slight insolation
corresponds to a solar altitude from 15 to 35 with clear skies.
Table 170, Solar Altitude, and Azimuth in the Smithsonian Meteor-
ological Tables (List, 1951) is a considerable aid in determining
insolation. Cloudiness will generally decrease insolation and
should be considered along with a solar altitude in determining
insolation. Insolation that would be strong with clear skies may
be reduced to moderate with broken middle clouds and to slight
with broken low clouds. Night refers to the period from one hour
before sunset to one hour after sunrise. The neutral category,
(D), should be assumed for overcast conditions during day or
ni ght .
246
Table 4.10-1
Key to Stability Categories
Night
Surface Wind
Speed (at 10 m)
m/sec
Strong
Insolation
Moderate
Slight
Thinly Overcast
or
> 4/8 Low Cloud
< 3/8
Cloud
< 2
A
A-B
B
-
-
2-3
A-B
B
C
E
F
3-5
B
B-C
C
D
E
5-6
C
C-D
D
D
D
> 6
C
D
D
D
D
The neutral category, D, should be assumed for overcast conditions during
day or night.
247
Estimation of Vertical and Horizontal Dispersion
Having determined the stability class
the measures
zontal ,
from the
sou
of diffusion in the
may be estimated as
from Tabl e 4. 10-1 ,
vertical, az , and in the hori-
rce ,
and
a function of downwind distance
(x), using Figures 4.10-3 and 4.10-4. These
ov/ are valid for concentrations, (C), averaged
Val UeS Of Oz aim u»
over a few minutes time, and apply to open level country with no
allowance made for turbulence due to buildings or topography.
With yery light winds on a clear night, the vertical spread may
be less than the values for class F.
tempe
ti on ,
allow
conve
still
be as
(2x )
earth
to 0.
tance
trat i
pi ume
When conditions are such that the vertical structure of
rature indicates a definite limit to the vertical convec-
particularly under unstable conditions, the oz should be
ed to increase only to 0.47h, where h, is the limit of
ction. At the distance x, where oz = 0.47 h,, the plume is
assumed to have a Gaussian vertical distribution. It can
sumed that by the time the plume travels twice this distance
, the plume has become uniformly distributed between the
's surface and the limit of convection. A value of az equal
8h, may be used and the exponential term dropped at dis-
s equal to or greater than 2x, and will make the concen-
on value computed by the equation, equal to that from a
uniformly distributed in the vertical.
Estimation of Wind Speed
For mean wind speed, (u), the
meters elevation (surface wind) should be
1 km for surface sources or short stacks,
or elevated sources, a mean speed through
the plume (about 2 az ) should be used,
the surface and geostrophic speeds should
val ue measured at 10
used for x up to about
For greater distances
the vertical extent of
A speed midway between
be reasonable.
Calculation of Centerline Concentration From a Ground Level
Source
For most practical purposes it will be sufficient to
calculate the centerline concentration for the distances 100 m, 1
km, 10 km, and 100 km and plot these against downwind distance x,
on log/log graph paper for interpolation of concentration for
other distances. (For unstable or stable cases it is desirable
to include several other distances.) This may be done using the
equat i on :
3.18 X
10 -1 Q
4.10-6
u
248
I 10
DISTANCE DOWNWIND, km
Figure 4.10-3
Vertical Dispersion Coefficient as a Function
of Downwind Distance from the Source
249
10,000
1,000
I 10
DISTANCE DOWNWIND, km
Figure 4.10-4
Horizontal Dispersion Coefficient as a Function of
Downwind Distance from the Source
100
250
The zero subscript of C, concentration, indicates emis-
sion from a ground- 1 eve! source. If there is a limit to convec-
tion (h), concentrations should also be calculated for distances
Xi and x~ using oz = 0 . 47 h , and o z = 0.8 h, respectively. Line
segments connecting the calculated concentrations for the various
distances will give a plot of concentration with distance.
Calculation of Ground-Level Center! ine Concentration From an
E 1 e vated Source
from :
Concentrations from an elevated source may be calculated
,2
C =
7T U O O
y z
exp -
H'
2 O:
4.10-7
where H is the
pi us pi ume ri se
effective height i.e., the physical
of the elevated source.
stack height
Values of exp - Wc H °z c are found in Table 4.10-2. A
is the ratio of H/ o2 and B, the expression in the body of the
table, is the computed value of the exponential. The E repre-
sents x 10 to the power indicated by the following two digits.
For9exampl e , if A = 3.55, the value of the exponential is 0.183 X
10 .
It is possible under light wind situations at nights
that the plume from an elevated source will remain aloft with no
significant vertical diffusion, in which case the ground-level
concentrations would be zero. Vertical spread can then be
started at a downwind position corresponding to the wind speed
and the estimated time for breakdown of the stable situation.
Graphs for Estimation of Diffusion
Hilsmeier and Gifford (1952) have presented graphs of
relative concentration times wind speed (Cu/Q) below the plume
centerline, versus downwind distance for various stability
classes. Figure 4.10-5 give Cu/Q as a function of x for a
ground-level source whereas Figures 4.10-6 through 4.10-8 are for
the indicated elevated sources.
Calculation of Off Axis Concentrations
4.10-1,
by the factor:
Off-Axis concentrations may be calculated from equation
or by correcting ground- 1 evel centerline concentrations
exp - (y /2o ). This may be obtained from Table
4. 10-3 for val ues of y/ o
Plotting Ground-Level Concentration Isopleths
251
Table 4.10-2
Values of Exp -
2a.
0.00
0.01
o.ao
o.io
o.?o
0.30
c.»o
o.»o
0.60
O.'O
o.bo
0.90
.00
.10
1.20
I.JO
.*o
.so
.60
.70
.80
.90
.00
.10
.20
.50
.*o
.50
.60
.70
.80
.90
.00
.10
.20
.30
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.50
.60
.70
.80
■ 90
.00
.10
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.30
'.50
>.6C
.to
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C.lOOf
01
0
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0
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0
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.976£
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252
Table 4.10-2 (Continued)
B • exp - i (A)2
*
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253
♦0
5
2
10°
s
2
a
C u 2
Q SO'2
K)
K>
10
10
Lm\n
w1 \.\
l
ivxS
>0 N
sj>
!
j
^.j"
I>V
i
i
SJ rk. ^v
ft
1
IjV
1
VI |K "
.
jX I IX
s^
-
i!
^L
, ]\.n\i
^F
1 1
Xa n
£
x T
jSOii
l\
\J
S. 1
T^
TSJj_ii
»' 2
♦0'
5 *03 2 5 »'
* (iMttrt)
5 «0"
Figure 4.10-5
Values of ^r for a Ground Level Source
254
K>"
10
C u
Q
C
K)
-5
H •
10 m
Y^\
<m ■
y
" k . L
V ^
k ^
/ \ V i\ \
k \
1 \ A.I \ ^
1 V r
\ — \~*~
•y\ \1 v-
v \
IV \! \! \
1 1 'V V
V
\ 1
\
\
LA
\ \ \ \
\ p
1
\
10'
10-
2 5
m (m«tefi)
10'
10"
Figure 4.10-6
Values of -If- for H = 10 meters
1 meter = 39.37 inches
255
10
10
C u
Q
-4
K>
-5
10
-6
I
H -30 m
1 / \
i '
\ f\ ~\
A
L/-i—
I '
A !
V i
¥ \1
\
V
s
\a
\ x
J _l
/
, \l
VI \
1 i
A
10'
io-
2 5
/(meters)
10'
10:
Figure 4.10-7
Values of -^ for H = 30 meters
1 meter = 39.37 inches
256
10
-4
to
-5
C u
Q
♦0
K)
-7
— , ,_
*$V\
H-
100 m
\4-~ -\ ^m
_..
Ll
~\ — \x
—V
T \.
\
\ # \! #
r N.
B
f
■-\-S
cf-
/ \/
" tf"
—
f i I
vJ. -
-LLe/L
f
/
Dj
/
1
♦0'
I03
2 5
10'
O'
Figure 4.10-8
Values of ^ for H = 100 meters
1 meter = 39.37 inches
257
Table 4.10-3
2 2
Values of Exp (y /2a ) for y/o
y/ay
exp (y2/2oy2)
0
1.00
0.1
1.01
0.2
1.02
0.3
1.05
0.4
1.08
0.5
1.13
0.6
1.20
0.7
1.28
0.8
1.38
0.9
1.50
1.0
1.65
1.2
2.05
1.4
2.66
1.5
3.08
1.6
3.60
1.8
5.05
2.0
7.39
2.15
10
3.04
10?
3.72
103
4.29
104
4.80
105
258
It may be of interest in a given application to plot the
position of the centerline of the plume and to determine areas
covered by concentrations greater than a given magnitude. First
the axial position of the plume must be known. The mean wind
direction will determine the position. The surface wind may be
used up to 1 km. Between 1 km and 100 km, the average of the
surface direction and the geostrophic direction backed (counter-
clockwise change in direction) by 10 will give a close approxi-
mation. The wind direction should be a mean through the vertical
extent of the plume (about 2 a).
easi
c )
cent
off-
corr
3) a
4.10
the
thes
draw
assu
If t
over
the
wi dt
the
In order to draw lines of equal concentration, it pis
est to locate the centerline concentration, that is exp (y / 2
times the concentration desired, on a log/log plot of
erline concentrations against distance. The value of y (the
axis distance), can then be found by knowing the y/°v value
esponding to the appropriate exp (y /2 a ) (See TablTa 4.10-
nd the value of for this particular distance (from Figure
-4). The position corresponding to the downwind distance and
off-axis distance can then be plotted. After a number of
e points have been plotted, the concentration isopleth may be
n and the area determined by using a planimeter. This
mes that the plume has a Gaussian distribution across wind,
here is a systematic veering or backing of the wind direction
a range that is large compared to the width of the trace,
plume may be assumed to be uniform in distribution across the
h (4.3 o ) of the plume and the concentration will be 0.58 of
calculated centerline concentration.
Areas Within Concentration Isopleths
Figure 4.10-9 gives areas within ground-level concentra-
tion isopleths in terms of Cu/Q for a ground-level source for
various stability categories (Hilsmeier and Gifford, 1962).
Rapid Determination of Maximum Concentration
The maximum concentration of pollutants will occur along
the centerline of the plume where y is zero, as indicated in
equation 4.10-7 above. The distance downwind, at which the
maximum concentration occurs at ground level, is a function of
effective source height and stability. Figure 4.10-10 is a
nomogram from which the relative value of the maximum concentra-
tion can be determined given the stability and effective source
height. If the relative value of that concentration is multi-
plied by Q/u , the maximum concentration for a specific set of
conditions is obtained. The nomogram is designed for source
strength expressed in grams/sec and wind speed in meters/sec.
Accuracy of Computations
The method will, in general, give
estimates of concentrations, especially if
measurements are not available and estimates
only approximate
wind fluctuation
of dispersion are
259
I/Ill
i
m i
J
J t
J * £
r
f f
* i !
/
J /
r I *
/
/ ' '
1 i
/ 4
f / /
}
/ /
t J
1 I
/ /
f 1
/ /
/
/
' / /
/ /
f t
u.
UJ o
U CD
<
9>
O
CD
O
o
O
o
O
(2w) v3av
Figure 4.10-9
Area Within Ground Level Concentration Isopleths for
Values of Cu/Q and Atmospheric Stability
I
O
in
CM
ro
I
O
\r>
cm —-
i
o
If)
CM
I
O
to
CM
ID
O
260
Distance in meters from source to maximum
ground level concentration
o
1 — I
o
CD
CD
5-
O
OO
c
o
TO
C OO
CD CD
U 00
C CO
O (T
O r—
E
2 >>
X f—
fO T-
s: jo
ro
O c/l
O) T3
ZJ E
i— ro
(0
QJ
>
rO
CD
•i —
CD
CD CD
C£ U
5-
"O 3
C O
TO 0O
CD to
O 3
S- O
13 -r-
O S-
o
CD
o
e
ro
+->
Q
00
CU
U
c
1-^
CI
00
S-
CD
CD
261
obt ai n
stabl e
travel
within
tances
neut ra
ki 1 ome
above
10 km
genera
i n d e f i
the pi
al lowe
of sta
km cal
by an
c o n d i t
of 5 o
ed from Figures 4.10-3 and 4.10-4. In the unstable and
cases, errors of a of several fold may occur for longer
distances. There are cases where o may be expected to be
a factor of 2. These are: 1) alf stabilities for dis-
of travel of a few hundred meters in open country; 2)
1 to moderately unstable conditions for distances of a few
ters; and 3) unstable conditions in the first 1000 meters
ground with a marked inversion thereafter for distances of
a
yr
are l n
or more. Uncertainties in the estimates of
1 less than those of az except when the wind "field is
nite. In this case, the estimate of concentrations from
ume would be the same except that a wind range should be
d for the direction of the plume, up to 360 . For extremes
ble and unstable conditions at distances between 50 and 100
culated concentrations may differ from true concentrations
order of magnitude. For these distances, under neutral
ions, calculated concentrations should be within a
f true concentrations.
factor
EXERCISES WITH DIFFUSION PARAMETERS
1. What stability category would be most likely to occur when
the wind is 6 - 8 m/sec? (D)
2. If the sky is overcast - synonymous with cloudy - what would
the stability category most likely be? (D)
3. What would the stability category most likely be on a sunny
April afternoon when the wind is 3 m/sec? (A or B)
4. If the surface wind at night is 3 m/second there is 5/8
coverage of low clouds, what is the most likely stability
category? (D or E)
5. What are o and a at 150 m from a source under B stability?
(oy = 2 7.5 nt , az = 15.5m)
6. How much difference is there in az at 5 km under D and F
stability? (55m)
7. What is the value of a at 30 km under C stability? (2200m)
8. At 300 m how many times larger is cy under B stability than
under D stabi 1 i ty? (2.4)
9.- Under E stability how much greater is the horizontal disper-
sion factor than the vertical dispersion factor at 300m?
(7.7)
10. If the value of H/ a is 1.8, what is the value of exp -
- 1/2 (H/o2)2? (1.6)
11. The value of exp - l/2(H/o )2 is 2.2 x 10"3. What is H/ o ?
(3.49) z z
262
12. Under D stability and a wind speed of 5 m/sec, a plume is
emitted at 100 m above the ground. What is the value of C/Q
at 4 km? fi 7
(1.4 x 10"° sec/m"3)
13. What is^the^area enclosed by an isopleth whose Cu/Q-value is
4 x 10' m , when the stability category is B? (10 m)
I EXAMPLE DIFFUSION COMPUTATIONS
#1 A power plant burns 10 tons per hour of 3% sulfur coal,
releasing the effluent from a single stack. On a sunny summer
afternoon, the wind speed at 10 meters is 4 m/sec from the north-
east. The morning radiosonde run in the vicinity has indicated
that a frontal inversion aloft will limit the convection to 1500
meters. The 1200 meter wind is from 30° at 5 m/sec. The effec-
tive height of emission is 150 meters. What is the maximum
concentration and where does it occur?
Solution: On a sunny, summer afternoon the insolation
should be strong. From Table 4.10-1, strong isolation and 4
m/sec wind yields class B stability. The amount of sulfur burned
i s :
Sulfur =
10 tons
hour
2000 lbs
ton
0.03 sulfur = 600 lbs/hr
Sulfur has a molecular weight
molecular weight of 32;
burned, there results two
Q =
2 SO
2
of 32 and combines with 0~
therefore, for e\/ery pound of
pounds of SO
600 lbs. S
hr.
2*
453.6 gms/1 b.
3600 sec/hr
with a
sul fur
= 151 gms. SO /sec.
The maximum concentration may be found by using Figure
4.10-10. Given stability class B and effective source height of
one may enter the nomogram and read the Cu/Q value of 8 x
150 m
10 from the
usi ng
abscissa,
the wind
strength, Q, of 151 gms
(max)
= 8 x 10
Solving for the maximum concentration, C
speed, u, of 4 m/sec and the source
SOp/sec yields.
151 qms/sec = 3 x
4 m/sec
10
-4
gm/rrf
The distance from the power plant at which the maximum
concentration occurs under these meteorological conditions can be
read from the ordinate in Figure 4.10-10. This distance is
1000m.
263
#2 Using the conditions in the above problem, draw a graph
of centerline sulfur dioxide concentrations beneath the plume
with distance from 100 meters to 100 km.
vection to
700 meters
2 x, = 11.0
usea to find
Sol ut i on : Since the frontal inversion limits the con-
= 1500 meters, the distance where o = 0.47 h, =
5.5 km. At distances equal to orz greater tnan
j = 0.8 hl = 1200 meters. Equation 4.10-7 is
concentration as a function of distance.
."1
1 s X-,
km ,
C =
151
tt u a
exp
In this case H = 150 meters. Solutions for this equa-
tion are given in Table 4.10-4. The values of concentrations in
Table 4.10-4 are plotted against distance in Figure 4.10-11.
#3 Draw a graph of concentration versus cross-wind distance
at a downwind distance of 800 meters for the conditions of prob-
1 ems 1 and 2 .
Solution: From probJem 2, -,the centerline concentration
at 800 meters is 2.9 X 10" gms/m . To determine the concen-
trations at distances y from the x axis, the centerl i ne Oconcen-
oy =
X aXIS, UIIC bCIUCI I I ME ry
tration must be multiplied by the factor exp -l/2(y/aM)
120 meters at
gi ven in Table
x = 800
4.10-5.
meters. Values for this computation are
The preceeding exercises illustrate one of the simplest
approaches to air quality modeling. Numerous levels of sophis-
tication can be incorporated into the basic Gaussian modeling
approach to determine pollution concentrations at downwind recep-
tor locations. As mentioned before, the next level incorporates
mathematical simulations of plume rise. Plume rise is mainly a
function of momentum and thermal buoyancy. Terms related to one
or both of these factors are included in nearly all plume rise
formulas. For cold stacks (JETS), those with emissions of less
than 10 to 20 F above ambient, momentum is probably the most
important factor. On the other hand, for hot stacks, when gases
are warmer than 200 F, buoyancy is the most important aspect of
the plume rise formula. Numerous plume rise formulas have been
proposed by a multitude of qualified investigators. No one
formula provides the best estimate for all types of stacks and
atmospheric conditions. The most widely accepted plume rise
formulas were derived by Holland (1953) and Briggs (1969). The
basics of their plume rise simulation formulae are applied by
most Environmental Protection Agency (EPA) accepted air quality
model s .
264
Table 4.10-4
Solutions for Problem #2
Col.
Col.
Col.
Col.
Col.
Col.
Col.
a
b
c
d
e
f
g
X
(km)
u
(m/sec)
y
m
a
z
m
z
- - <€>
C
gms /m
0. 3
4
52
30
5.0
-6
3 X 10
2. 3 x io"8
0. 5
4
77
53
2.83
_9
1.7 X 10 "
5.0 X io"
0.8
4
120
93
1.61
0.27
2.9 X 10
1
4
150
125
1.20
0.48
3. 1 X IO"4
2.8
4.5
375
700
0.21
0.98
4.0 X 10_:
5.6
4. 5
700
1200
0. 125
0.98
1.25 X io"5
10
4.5
1200
1200
0. 125
0.98
7.3 X IO"6
100
4.5
8400
1200
0. 125
0.98
1.04 X 10'6
Col. c from Figure 4.10-4
Col. d from Figure 4.10-3
Col. e 150 m over value in Col. d
Col. f Value in Table 4.10-2 corresponding to H/oz in Col. e
Col. g Solution to equation 4.10-7
Table 4.10-5
y
(m)
y/a
y
exp - { (y/a )
C(y)
gms /m
+ 1C0
0. 834
0.7
2.03 X IO*4
+ 200
1.67
0. 25
7.25 X io'5
+ 300
2. 5
4. 2 X 10
1.22 X jo
+ 400
3. 33
3. 7 X io""3
c
1. 07 X ]0"
This is graphed in Figure 4.10-12
265
1 m = 3.281 feet
1 km = 0.6214 miles
1 m/s = 3.281 feet/second
1 gm/m3 = 6.243x10-7 lbs/feet3
10
10"
■3
Concentration
so2
gm» /m
10
io-
.5
10
-7
10'
-+
,
rz=a
-
-
-
,
-
_
c=
■
V-
—
.,
^
4-
:
- T— *d.~
1 ,
V
^^
— p-
\
-
._
-
.
1 1 .
1
-
-h
I
' 1 "'
.
-H
- ".
T^
1
\-
•
i
--
—
i
0 1
10
Di»t»nce (Km )
100
Figure 4.10-11
3
Concentration of S0o (gms/m ) as a Function of Distance
(km). (Problem 2)
1 gm/ 3 = 6.243 x 10"7 lbs/ft3
3 m
1 km = 0.6214 mi
2 x 10"1
sc2
Concentration
gm/m
io-
10
.5
-400 -300 -200 -100 0 100 200 J00 400
y Di»t»nce ( Mete r • )
Figure 4.9-12
Concentration of S02 (gms/m3) Across Wind at a Distance of 800 Meters
(Problem 3)
266
1 gm/ 3 = 6.243 x 10"7 lbs/ft3
3 m
1 m = 1.094 yds
Briggs in his recent publication, PI ume Ri se (1969), has
presented both a critical review of the subject and a series of
equations applicable to a wide range of atmospheric and emission
conditions. These equations are being employed by an increasing
number of meteorologists and are used almost exclusively within
EPA. An important result of this study is that the rise of
buoyant plumes from f ossi 1 -?-f uel plants with a heat emission of 20
me-gawatts (MW) - 4.7 x 10 cal/sec - or more can be calculated
from the following equations under neutral and unstable condi-
t i ons .
where :
AH
AH
1.6 F
1 .6 F
1/3
1
2/3
1/3 -1
(10
hs)
2/3
4. 10-8
4. 10-9
H = plume rise
F = buoyancy flux
u = average wind at stack level
x = horizontal distance downwind
_ = physical stack height
of the stack
Equation 4.10-8 should be applied out to a distance of
10 h from the stack and equation 4.10-9 can be used for greater
distances.
The buoyancy flux term, F, may be calculated from:
F =
g Q
- c p pT
- 3.7 x 10
4. 3
m /sec
cal/sec
4.10-10
where
g
Qh
c
p
T
gravitational acceleration
heat emission from the stack, cal/sec
specific heat of air at constant pressure
average density of ambient air
average temperature of ambient air
: Alternatively, if the stack gases have nearly the same
specific heat and molecular weight as air, the buoyancy flux may
be determi ned from :
F =
A T
4.10-11
Notation has been previously defined.
267
In stable stratification,
a di stan
stabi 1 i ty parameter :
_e,q ua tion 4.10-8 holds approxi-
mately to a distance x = 2.4 us " ' . S may be defined as a
s = S.
T
d e
3 Z
4.10-12
where
3 9
9 z
; lapse rate of potential temperature
eyond this point the plume levels off at about
c \ 1/3
A H = 2.4
4.10-13
u s
However, if the wind is so light that the plume rises
vertically, the final rise can be calculated from:
AH = 5.0 F1/4 s"3/8
4.10-14
For other buoyant sources, emitting less than 20 MW of
heat, a conservative estimate will be given by equation 4.10-8 up
to a di stance of :
x = 3x'
4.10-15
where :
= 0.52
sec
ft
6/5 1
6/5
p2/5 h 3/5=
4.10-16
which is the distance at which atmospheric turbulence begins to
dominate entrainment.
Sophisticated modeling more complex than the simple
Gaussian are often required. These sophisticated algorithms
applied to the basic Gaussian approach include the computation of
downwind ground level concentrations as a function of stability
class and wind speed. Such an approach would incorporate wind
speeds as a function of stability class. Further sophistication
in the Gaussian modeling approach would incorporate relative
frequency distributions of wind speeds, wind direction and sta-
bility class. This type of model would be useful in isolating
long-term air pollution concentrations in the study area.
There is a
with regard to the
of each generation
limitless number of levels of sophistication
Gaussian model. The accuracy and refinement
of the model depends upon the quality and
268
resolution of the data base used. As the problem becomes more
complex, more sophisticated numerical models must be employed
particularly in instances where terrain or conversion effects
become important. Such modeling is beyond the scope of this
document, however the EPA may be contacted for more information
on dispersion models such as the CI imatol og i cal Dispersion Model
(CDM), the Air Quality Display Model (AQDM) , the Valley Model,
and the Texas CI imatol og i cal Model (TCM).
269
4.11 ASSISTANCE IN DISPERSION METEOROLOGICAL PROBLEMS
References
t Abstracts
Meteorological and Geoast rophysi cal Abstracts
American Meteorological Society
45 Beacon Street
Boston 8, Mass.
Peri od i cal s
Bulletin of the American Meteorological Society
American Meteorological Society (See above)
Journal of Applied Meteorology
American Meteorological Society
Journal of the Atmospheric Sciences (formerly
Journal of Meteorology)
American Meteorological Society
Monthly Weather Review
U.S. Dept. of Commerce
Weather Bureau, Washington, D.C.
Quarterly Journal of the Royal Meteorological
Soci ety
Royal Meteorological Society
49 Cromwel 1 Road
London , S. W. 7
• Books
American Meteorological Society, On Atmospher i c
Pollution,
Meteorological Monographs, 1, 4, Nov. 1951.
Geiger, R. (Transplanted by Scripta Technica Inc.)
The Climate Near the Ground.
Rev. ed., Harvard University Press
Cambridge, Mass. 1965.
Professional Meteorological Consultants
Professional meteorologists advertise their services in
the Professional Directory section of the Bulletin of the Ameri-
can Meteorological Society. In the May 1979 Bulletin, 83 such
firms and individuals were listed. The American Meteorological
Society has in the last several years instituted a program of
270
certifying consulting meteorologists,
services listings in the Bulletin, 40
Meteorologists.
Of the 83 professional
list Certified Consulting
Local U.S. National Weather Service Office
A wealth of meteorological information and experience is
available at the local city or airport Weather Service Office
pertaining to local climatology, pecularities in local micro-
meteorological conditions including topographic effects, and
exposure and operating characteristics of meteorological instru-
ments. The Air Stagnation Advisories are received here by tele-
type from the National Meteorological Center. Often the public
telephones the Weather Service with air pollution complaints
which the meteorologists may have traced back to a specific
source by examining local wind circulations. Through personal
contact with the meteorol og i st- i n-charge (MIC), specific, local-
ized forecasts may be arranged to support a short-term air pol-
lution investigation or sampling program.
Contract Work
Many universities do contract work for private organi-
zations and for government agencies on meteorological problems.
271
4.12
GLOSSARY OF TERMS
Ad i abat i c
Ad'i abat ic
Di agram
Advect i on
I nversi on
Aerodynamic
Air Basi n
Air Flow Pattern
Air Parcel
Al gori thm
Backi ng
A thermodynamic change of state of a system in
which there is no transfer of heat or mass
across the boundaries of the system. In an
adiabatic process, compression always results
in warming, expansion in cooling.
A thermodynamic diagram with temperature as
abscissa and pressure to the power 0.286 as
ordinate, increasing downward.
A type of inversion which occurs over an area
due to the horizontal transport of a stable
layer (e.g., marine inversion noted along
coastal California are the result of the
advection of cool, stable air from the nearby
Pacific.
Pertaining to forces acting upon any moving
solid or liquid body other than a stationary
object relative to a gas (especially air).
An area created by topographic boundaries
which serves to contain air pollutants emitted
into the area by pollution sources and to
restrict air exchange with other air basins.
The typical movement of air currents as
graphed on wind roses.
An imaginary body of air to which may be
assigned any or all of the basic dynamic and
thermodynamic properties of atmospheric air.
A procedure for solving a problem (as in
mathematics) that frequently involves repeti-
tion of an operat i on .
According to general internationally accepted
usage, a change in wind direction in a coun-
tercl oc kwi se sense .
B i m o d a 1
Black Body
Buoyancy Fl ux
A distribution having two maxima.
A body which absorbs all incident electro-
magnetic radiation; i.e., one which neither
reflects nor transmits any incident radiation.
An empirical term used in plume rise calcula-
tions to define the heat content of an indus-
trial source.
272
Burn/No-Burn
Calm
Centerl ine
Concentrat i on
Channel i ng
Cold Stacks
(Jets)
Condensation
Level s
Used to determine when weather conditions
Forecasts favor the rapid dispersion of pollu-
tants created by the burning of agricultural
wastes and other industrial operations.
A period when the
United States, the
it has a speed of
( or one knot) .
air is motionless. In the
wind is reported as calm if
less than one mile per hour
The concentration of gaseous pollutants or
aerosols at the center of the plume.
The effect of terrain, particularly valleys,
in modifying the prevailing winds along the
path of lowest terrain heights.
Cold, non-buoyant sources with
peratures less than 10 to 20°F
temperatures .
emission tern-
above ambient
The 1 evel
1 i f ted dry
rated .
at which a parcel of moist air
adiabatically would become satu-
Coning
Constant Level
Ball oons
Convective
Thundershowers
Diffusion
Digitized Data
Dispersion
Model i ng
Di spersion
Potent i al
When the vertical temperature gradient is
between dry adiabatic and isothermal, slight
instability occurs with both horizontal and
vertical mixing. An industrial plume tends to
become cone shaped, hence the name.
A ball oon des i gned
pressure level .
Showers caused when
to rise rapidly.
to float at a constant
layers of air are forced
In meteorology, the exchange of fluid parcels
between regions in space, in the apparently
random motions of a scale too small to be
treated by the equations of motion.
Data which is recorded in a computer accep-
table format (as opposed to analog or strip
chart dat a) .
The mathematical representation or simulation
of transport precesses that occur in the
atmosphere .
The ability of a system such as the atmos-
phere, to dilute the concentration of a sub
stance or pollutant by molecular and turbulent
motion; e.g., smoke in the air.
273
Di urnal
Downwash
Dra i nage Fl ow
Dry Adiabatic
Rate
Effective Stack
El evated
Inversion
Empi r i cal
Daily, especially pertaining to actions which
are completed within twenty-four hours and
which recur every twenty-four hours.
The condition resulting when strong winds push
a plume rapidly to the surface, resulting in
high ground-level pollution concentrations.
The phenomenon is usually observed in the lee
of b u i 1 d i ngs .
The movement of cold air off high ground,
caused by gravity and typical of mountainous
reg ions .
The rate of decrease of temperature with Lapse
height when dry air is lifted ad i abat i cal 1 y
(due to expansion as it is lifted to lower
pressure) .
The physical stack height plus plume rise,
i.e., the point above ground at which the
gaseous effluent becomes esentially level.
An inversion layer above the immediate sur-
face. Such an inversion inhibits dispersion
of bouyant pollutants, such as those given off
by power facilities and refineries.
An approach based upon observation and experi-
mentation.
Env i ronmental
Lapse Rate
Exit
Characteristics
Fann i ng
Fire Management
Fire Weather
Fluid Dynamics
The actual rate of decrease of temperature
with elevation at at given time and place.
Parameters pertaining to a gas exiting from a
stack including gas temperature, exit veloci-
ty, emission rate, stack height, and stack
d i ameter .
When the atmosphere is stabily stratified, an
industrial plume will spread horizontally but
little if any vertically.
The practice of controlling range undergrowth,
such as chapparal, through controlled burning.
The state of the weather with respect to its
effect upon the kindling and spreading of
forest f i res .
The level of physics that treats the- action of
force on fluids and gases in motion or at
rest .
274
Freezing Level
Front
Frontal
Inversion
Fugitive Dust
Fug i t i ve Source
Fumigation
Gaussi an
Diffusion
Equat i on
Hori zontal
Di spersi on
Coefficient
Induced Flow
Insolation
Inversion
Inversion Layer
Isopl eth
I sothermal
The lowest altitude in the atmosphere over a
given location at which the air temperature is
32°F.
The transition zone between two air masses of
different densities.
A temperature inversion encountered in the
atmosphere, upon vertical ascent through a
sloping front.
Solid air borne particles emitted from any
source other than a stack.
A source emitting pollutants other than from a
stack.
The rapid mixing of a fanning plume down to
the ground, such as during inversion breakup.
An equation used to evaluate the concentration
of gases or aerosols assuming a Gaussian or
normal di str i but i on .
The horizontal standard deviation of plume
pollutant concentration. The parameter varies
as a function of downwind distance and atmos-
pheric stability.
A flow of air caused by uneven heating of
terrain and its associated air parcels.
Solar radation received at the earth's sur-
face .
A departure from the usual decrease or in-
crease with altitude of the value of an atmos-
pheric property (almost always of tempera-
ture). In a temperature inversion, tempera-
ture increases with altitude. A temperature
inversion is stable, allowing little turbulent
exchange to occur.
That layer of air which departs from the usual
decrease in temperature with increasing
al t i tude .
A line of equal or constant value of a given
quantity, with respect to either space or
time.
Of equal or constant temperature, with respect
to either space or time.
275
Jet (Low-Level )
K -Theory
Land Breeze
Lapse Rate
Line Source
Loft i ng
Loopi ng
Mixing Height/
Depth
Mixing Layer
Momentum Exchange
Mountain Flow
Neutral
Atmospher i c
S t a b i 1 i t y
Nocturnal Ai r
Fl ow
A high-speed wind that attains its velocity
through channeling due to terrain configura-
tion such as a narrow mountain pass or canyon.
K-theory or gradient transport theory assumes
that turbulent diffusion is proportional to
the local mean concentration gradient.
A coastal breeze blowing from land to sea,
caused by the temperature difference when the
sea surface is warmer than the adjacent land.
The decrease of an atmospheric variable (al-
most always temperature) with height.
A source of pollutants occurring at a reason-
ably continuous rate along a fixed line (e.g.,
h i ghway ) .
Lofting of an industrial plume occurs when
there is a superadiabatice layer above a
surface inversion. It is a condition which
encourages diffusion upward but not downward
because of the presence of a stable layer
bel ow.
The looping of an industrial plume occurs with
a superad i abat i c lapse rate.
Height (Depth) of the layer of air where well-
mixed conditions exist, usually the height of
the first significant inversion above the
surface .
That thin layer of the troposphere available
for the dispersion of pollutants released near
the surface .
The turbulent transfer of momentum; the pro-
duct of mass and velocity.
The regular flow of air around portions of
raised terrain. Air will stream toward and up
mountain slopes during the day and downward
and away during the night.
Neutral stratification of the atmosphere,
i.e., the lapse rate is equal to the dry-
adiabatic lapse rate, therefore, a parcel of
air displaced vertically will experience no
buoyant acceleration.
A flow pattern characteristic of clear nights
and rapid radiational cooling, which tends to
stabilize the atmosphere promoting air flow
from higher terrain towards low lying areas.
276
Nucleation
Numeri cal
Model i ng
Orographic
Pasqui 1 1 ' s
Stability
Categories
The condensation out of molecules on airborne
part i cl es .
The development of a means of computing the
future state of the atmosphere from the basic
theoretical equations which govern that state.
Of, pertaining to, or caused by mountains.
Stability classes as defined by Dr. F. Pas-
quill of the British Meteorological Service,
including extremely unstable, unstable,
slightly unstable, neutral, slightly stable,
and st abl e .
Persistence
Time period over which a certain parameter is
mai ntai ned .
Phys i cal
Model i ng
Physical modeling is based uopon the actual
simulation of events in the real atmosphere or
in a seal e model .
Physical Stack
Height
PI ume
PI ume Rise
Positive Net
Radiation
Prevail i ng
Wind(s)
Prof i 1 e
Pseudo-Adiabatic
Lapse Rate
Radi at i onal
Cool i n g
Actual height of a stack, i.e., a pollutant
source .
A large, conspicuous cloud of smoke, dust, or
water vapor arising from a stack.
The velocity and heat of an industrial source
will cause it to rise to a certain height.
The difference between this height and the
physical stack height is called plume rise.
Amount of incoming solar radiation in excess
of outgoing terrestrial radiation.
The wind direction(s) most frequently observed
during a given period.
A graph of the value of a scalar quantity
(such as temperature) versus a horizontal,
vertical, or time scale.
The rate of decrease of temperature with
height of an air parcel lifted at saturation
through the atmosphere. Less than the dry
adiabatic lapse rate.
Cooling of the earth's surface and surrounding
air accomplished (mainly at night) whenever
the earth's surface experiences a net loss of
heat .
Rad i at i onal
I nversi on
An inversion at the surface due to radiation
cool i ng.
277
Radiosonde
Re-entrainment
Regime
»
Screening Level
Sky Cover
SI ope Winds
Smoke Sensitive
Area
Sol ar Al ti tude
Sol ar Insolation
Sorpt i on
Sounding
Stability
Stabl e
STAR (STability
ARray)
A balloon-borne instrument used for measuring
and transmitting weather data, such as pres-
sure, temperature and humidity.
The mxing of environmental air into an organ-
ized air current of which it formally was a
member .
The character of the seasonal distribution of
a weather phenomenon at any place; e.g., the
summer sea breeze regime.
A simplistic approach designed to determine
the need for additional, more detailed ana-
lyses .
The amount of sky covered or concealed by
clouds or other obscuring phenomena.
Winds caused by uneven surface heating and
cooling in areas of rugged terrain.
An area which, due to high population density,
recreational value or scenic beauty, is con
sidered particularly sensitive to smoke plumes
from forest management burning.
The elevation angle of the sun above the
hori zon .
Solar radiation received at the earth's sur-
face .
The deposition of molecules due to collision
with an obj ect .
Any penetration of the natural environment for
scientific observation. In meteorology, com-
monly refers to the environmental lapse rate.
A measure of the extent to which vertical and
horizontal mixing will take place. Commonly
measured as unstable, neutral or stable.
The lapse rate is less than the dry adiabatic
lapse rate and vertical motion is suppressed.
A description of a type of meteorlogical
program developed by the National Climatic
Center in Asheville, North Carolina. The
program provides joint frequency d i s-t r i but i on s
of wind speed, wind direction, and atmospheric
stabi 1 i ty class.
278
Stability Wind
Roses
Stack
Statistical
Model i ng
Sub-Ad iabatic
Subsidence
I nver si on
Super-Ad iabatic
Surface Based
I nversi on
Surface Boundary
Layer
Surface Data
Surface Roughness
Synoptic Scale
Winds
Temperature
Prof i 1 e
Temperature
Soundi ng
Thermal Buoyancy
Diagrams designed to show the distribution of
wind direction experienced at a given location
over a desired time period for a given atmos-
pheric stability class.
Any chimney, flue, conduit, or duct arranged
to conduct emissions to the outside air.
Statistical modeling is based upon the sto-
chastic nature of turbulence and describes
diffusion as an ensemble average of many
particles emitted from a source.
A lapse rate which is less than the dry adia-
batic lapse rate (5.5°F per 1,000 feet).
A temperature inversion produced by the
warming of a layer of descending air. The
effect is the creation of a limited mixing
volume below the stable layer.
A lapse rate which is greater than the dry
ad iabatic lapse rate.
An inversion layer of stable air close to the
ground. Such an inversion inhibits dispersion
of fugitive dust and other non-buoyant sources
of pol 1 utants .
The thin layer of air immediately adjacent to
the eart h ' s surface .
Observations of the weather from a point at
the surface of the earth, as opposed to upper-
air or winds-aloft observations.
Irregulatities of the earth's surface (pro-
vided by trees, buildings, etc.) which in-
creases air turbidity, and consequently,
pollutant dispersion.
Strong winds created by weather patterns of
high and low pressure systems in the lower
troposphere .
A graph of temperature versus a horizontal,
vertical, or time scale.
Upper-air observations of temperature as taken
by a radiosonde.
The impetus provided by heat for an emission
to rise or remain suspended in the atmosphere.
279
Thermal Low
Trans port
Trappi ng
Tra j ectory
Anal yses
Tropopause
Troposphere
Typi cal
Conditions
Unstabl e
Val 1 ey Wi nds
Veering
Vent i 1 ate
Vert i cal
Ci re ul at i on
An area of low atmospheric pressure due to
high temperatures caused by intensive heating
at the earth's surface.
The rate by which a substance or quantity,
such as heat, suspended particles, etc., is
carried past a fixed point.
When an inversion occurs aloft such as a
frontal or subsidence inversion, a plume
released beneath the inversion will be trapped
beneath it .
The depiction of regional wind direction
patterns at the surface of the earth, as
generated from the most frequent wind direc-
tion occurring at each of several stations in
an area for- selected averaging periods.
The boundary between the troposphere
stratosphere .
and the
The lowest 10 to 20 km ( 6-12 miles) of the
atmosphere. It is characterized by decreasing
temperature with height, appreciable vertical
wind motion, appreciable water vapor content,
and weather.
The most commonly occurring combination of the
key dispersion factors - wind speed, wind
direction, and atmospheric stability class.
Knowledge of the most commonly occurring
dispersion condidtions provides some indica-
tion of the effect of an existing or proposed
pol 1 ut i on source .
The environmental lapse rate is
the dry adiabatic lapse rate
turbulence is enhanced.
greater than
and vertical
A wind which ascends a mountain valley during
the day.
According to general international usage, a
change in wind direction in a clockwise sense.
To cause to circulate as in the dispersion of
air pollutants.
The movement or mixing of air along a vertical
axis.
280
Vertical Dispel
Coefficient
Vertical Temp-
erature Profile
Vertical Wind
Prof i le
Virtual Source
Wind Tunnel
Winds Aloft
Worst-case
Conditions
The vertical standard deviation of plume sion
pollutant concentration. The parameter varies
as a function of downwind distance and atmos-
pheric stability.
A graph of temperature versus altitude.
A graph of the variation of mean wind speed
with height in the surface boundary layer.
The theoretical location of a point source
with respect to an actual area source which
would result in plume dispersion at the actual
point of emission indicative of the area
source .
A small scale model of the atmosphere which
permits experimentation in the laboratory.
Wind speeds and directions at various levels
in the atmosphere above the surface.
That combination of wind speed, wind direc-
tion, and atmospheric stability class that
would result in the greatest possible pollu-
tant impact of an existing or proposed source.
281
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1958", National Technical Information Service, U.S. Depart-
ment of Commerce, Springfield, Virginia, 22161.
U.S. Environmental Protection Agency, "Draft - Workbook for the
Comparison of Air Quality Models", Monitoring and Data Analy-
sis Division Office of Air Quality Planning and Standards,
Research Triangle Park, North Carolina, November, 1977.
U.S. Environmental Protection Agency, "Guidelines Series", 0AQPS
#1.2-080 October 1977, Office of Air Quality Planning and
Standards, Research Triangle Park, North Carolina.
U.S. Environmental Protection Agency, "Some Topics Relating to
the Modeling of Dispersion in the Boundary Layer", EPA-650/4-
75-015, Office of Research and Development, Washington,
D.C, April, 1975.
Yansky, G.R., E. H. Markee, Jr., and A. P. Richter, CI imatography
of the National Reactor Testing Station , Environmental
Science Services Ad ministration (January 1966).
283
5.0 BASELINE AIR QUALITY EMISSION LEVELS
5.1 FORMATION OF AIR POLLUTANTS
5.1.1 I ntroduct i on
Polluted atmospheres generally are associated with man's
industrial and domestic activities. However, many of the major
gaseous pollutants are also emitted by nature. Taken on a world-
wide basis, the total mass of trace gases emitted by nature
exceeds those emitted by man by several orders of magnitude.
Nonetheless, man's activities do adversely affect the quality of
the atmosphere, particularly in dense urban areas and near large
emission sources. For many of the pollutants, serious long-term
worldwide effects are feared. The effects may be immediate and
obvious, such as poor visibility, eye irritation, and objection-
able odors; or the effects may be noticeable only through longer
periods of observation, such as in corrosion. More subtle ef-
fects require sophisticated statistical studies to determine such
things as human health effects and changes in the earth's energy
bal ance .
Table 5.1-1 compares typical concentrations of pollu-
tants (Cadle, 1970) with those found in uncontami nated areas. It
can be seen that the ratio of concentration of polluted air to
clean air ranges from fractional to 1000-fold. Table 5.1-2 by
Robinson and Robbins (1972) summarizes the worldwide sources,
atmospheric concentrations, residence times, and removal reac-
tions for eight principal gaseous air pollutants. Except for
sulfur dioxide, emissions from natural sources exceed those from
pollution sources. Figure 5.1-1 and 5.1-2 show the relationship
between outdoor and indoor pollution levels for sulfur dioxide
and carbon monoxide. Measurements such as these indicate serious
penetration into homes near strong pollution sources (Benson, et .
al., 1972).
5. 1.2
The Gaseous Compounds of Carbon
The gaseous compounds of carbon found in natural and
polluted atmospheres comprise a broad spectrum of the compounds
of organic chemistry. Because carbon can form bonds with ele-
ments such as hydrogen, oxygen, nitrogen, and sulfur and at the
same time combine with itself to form a series of straight and
branched chain, cyclic, and combined cyclic-chain systems, an
almost infinite number of compounds are possible. Many gaseous
carbon compounds such as methane (marsh gas), carbon dioxide,
carbon monoxide, the terpenes (Table 5.1-3 [Rasmussen, 1972]),
and other volatile plant materials are emitted in nature through
biological processes, volcanic action, forest fires, natural gas
seepage, etc. In areas inhabited by man, the emissions of com-
merce, industry and transportation are largely concentrated in
urban areas and generate high local concentrations of volatile
solvents and fossil fuel combustion products.
284
Table 5.1-1
Comparison of Trace Gas Concentrations (ppm)
Ratio
CUan air
Polluted air
■polluted-to-clean
CO,
320
400
1.3
CO
0.1
40-70
400-700
CH4
1.5
2.5
1.3
N,0
0.2j
(?)
—
NO,(NO.)
0.001
0.2
200
0,
0.02
0.5
25
SO,
0.0002
0.2
1000
NH,
0 01
0.02
2
285
Table 5.1-2
Summary of Sources, Concentrations, and Major Reactions of Atmospheric Trace Gases
Calculated
Mi,or
\aturol
Ettimnted emiwoni {tons)
Atmoiphtrtr
background
atmoepheric
retidence
Be moral
reaction*
Contaminant
$OU"tl
$ourre»
Pollution Satural
concentration*
time
and ninks
Remark*
o,
fombu'tion
Volcanoes
146 X 10« No estimate
0 2 ppb
4 days
Oxidation to
Photochemira 1
<>' coal and
ml
sulfate by
otone or, a
absorption,
solid and li
aerosols
fter
by
quid
oxidation »ith
NOi and 1IC
may he the
process needed
to give rapid
Hts
CO
NO NOt
Ml,
NV)
Hydrocarbons
COi
Chemical
liriirewM.
Sew age
treat nient
Auto - (ha ■
an I other
combustion
( "Ti'.'jstion
None
( ombostion
ei haust,
rhernical
protsaaes
Comhuation
Volcanoe"
biological
action in
• » amp
area«
forest fire*.
oceans
ter|.pne
rear' ions
Rartenal
action in
BOll (')
Waste Biological
treatment decay
Biological
action in
■oil
llmlogical
processes
Biological
dersy
release
Irnm
oceans
3 X I0»
301 X 10"
53 X 10«
100 X I0»
33 X 10>
NO:
430 X 10*
NO-:
6-i8 X 10«
0 2 ppb
0 1 ppm
NO: 0 2-2 ppb
NOi: 0 5-4 ppb
4 X 10« 1 100 X 10i 6 pph to 20 ppb
None
500 X !"•
88 y 10« CM.
I ft X 10'
Terpenes.
2<MI X 10«
1 4 X 10'«
10"
0 25 ppm
CM.: 1 5 ppm
non Clli < 1 ppb
320 ppm
2 days Oxidation to SOi
<3 years
5 days
7 da>
4 years
4 years
(CH.)
2-4 years
Probably soil
organisms
Oxidation to
nitrate after
sorption by
•olid and lupjid
aerosols,
hydrocarbon
photochemical
reactions
Reaction w ith
SOi to form
(Nll.i-Sn.
oxidation to
nitrate
Photodi«sociation
in stratosphere,
biological
action in soil
Photochemical
react ion w it h
NO NO;. Of,
large sink
necessarv for
CM.
Biological
adsorption and
photosynt he*is.
absorption in
oceans
transformntion
of SO; — SO,
Only one set of
background
concentrations
available
Ocean contributions
to natural source
probably low
Very little work
done on natural
processes
Formation of
ammonium
salt* is major
NMi sink
No information
on proposed
absorption of
N,() h\
vegetation
"Rearm t"
hydrocarbon
emissions from
pollution —
27 X 10" tons
Atmospheric
concentrations
increasing by
0.7 ppm year
286
10
Ouidoo' c»rt>on monpaide cor>centr»lion |A) ppm
20 30 40
50
60
** 80
c
c
I 60
40 -
20 -
2 poinls
A 400% @ 0 2 pphm
1600% © 0 2 pphm
_l_
-j_
_i_
_l_
10 20 30 40
Ouldooi m'tu' diomde coocf rural. on <• pphm
50
60
Figure 5.1-1
Indoor concentrations of sulfur dioxide
and carbon monoxide as a function of
outdoor concentrations.
287
60
1 I !
Car being put in garage
1 1 1
C»r being taken from garage
-L-
1200 1700 2200 300 800 1300 1800 2300 400 900 '400
Mar S ' Mar 6 ' Ma' 7
Time hours
-I-
Figure 5.1-2
Carbon monoxide concentrations in house with gas range
and furnace and with attached garage. Solid line,
kitchen; dashed line, family room; dotdashed line, outside
288
Table 5.1-3
Worldwide Terpene Emission Estimates
Investigator
Method
Estimate in tons
WeDt'
Rasmussen and Went*
Ripperton, White, and
Jeffries'
Sum of sagebrush emission and
terpenes as percentage of
plant tissues
1. Bagging foliage
1 liter/lOcm'
2. Knclosure forbs 0.6o m'/m*
3 Direct »n titu ambient con".
Reaction rate ()|/pinene
175 X 10'
23 4 X 10"
13 5 X 10"
432 X 10'
2 to 10 X previous
estimates
• F. W. Went, Proc. A at. Aead. Sci. 46, 212 (19G0).
' R A. Rasmussen and F. W. Went, l'roe. Sal Acad. Set. 63, 215 (190.'.).
' L- A. Ripperton, O. White, and II. K. Jeffries, "Cias Phase Drone- Pinene Reactions,"
PP 54-56. Div. of Water, Air, and Waste Chemistry, 147th Nat. Meeting Amor.
Chem. Soc, Chicago, Illinois, 1967.
Not corrected for vertical foliage area over ground area.
Table 5.1-4
Estimates of Hydrocarbon Emissions, 1940-1970 (10 tons/year)
(United States)
Source category
1940
1950
1980
1968
1989
1970
Fuel combustion in
1.4
13
1.0
10
0.9
0.6
stationary sources
Transportation
7.5
118
18.0
20 2
19.8
19 5
Solid waste disposal
0 7
0 9
1.3
2 0
2.0
2.0
Industrial process losses
3.3
5.2
4.3
4.4
4.7
5.5
Agricultural burning
19
2.1
2 5
2.8
2.8
2.8
Miscellaneous
4.5
4.2
4 4
4.9
5.0
4.4
Total
19.1
25.6
31.6
35.2
35.2
34 7
Total controllable"
14.7
21.4
27.2
30.3
30.2
30.3
• Miscellaneous sources not included.
289
5.1.2.1 The Hydrocarbons
Table 5.1-4 shows the emissions of hydrocarbons in the
United States since 1940 (Cavender et al , 1973). Transportation
is by far the principal emitting source, and these data indicate
that its emissions seem to have peaked starting in 1968. Table
5.1-5 gives the average concentration for about 30 hydrocarbon
compounds identified and measured in Los Angeles, California air
(LAAPCD, 1970-72). More than 60 hydrocarbons have been identi-
fied, but the total number possible is yery large and is limited
only by the sensitivity and selectivity of the analytical method
used (USEPA, 1970). The compounds are classified into four major
functional types: alkanes (paraffins), al kenes (olefins), acety-
lenes, and aromatics. The concentrations are expressed in both
parts per million (ppm) and parts per million as carbon (ppm C).
The latter is calculated by multiplying the former by the number
of carbon atoms in the respective compound. Parts per million as
carbon is considered to be more representative of the hydrocarbon
burden of the ai r .
In themselves, the hydrocarbons in air have relatively
low toxicity. They are of concern because of their photochemical
activity in the presence of sunlight and nitrogen oxides (Tues-
day, 1971; Gordon et al , 1968). They react to form photochemical
oxidants of which ozone is predominant (Table 5.1-6). Oxidants,
including peroxyacyl nitrate (PAN), are responsible for much of
the plant damage and eye irritation associated with smog. Meth-
ane has ^ery low photochemical activity. As a consequence,
hydrocarbon concentrations are often measured separately as
methane on the one hand and non-methane hydrocarbons on the other
(Figure 5.1-3). Methane will vary from 40% to 80% of the total
hydrocarbons in an urban atmosphere (Figure 5.1-4 (Altshuller et
al , 1973).
Strictly speaking, hydrocarbons are the compounds of
hydrogen and carbon. At least two of the techniques used for
measuring "total" hydrocarbons in air include many other classes
of organic compounds. The nondi spers i ve infrared method (NDIR),
for example, measures compounds containing carbon- hydrogen bonds.
This includes most organic compounds. The flame ionization
method measures anything that reacts to form ions in a hydrogen
flame. Pure hydrocarbons give higher specific responses, but
without prior separation; the longer chain alcohols, aldehydes,
esters, acids, etc., also give responses.
5.1.2.2 The Oxygenated Hydrocarbons
The oxygenated hydrocarbons, like the hydrocarbons,
include an almost infinite number of compounds. They are classi-
fied as alcohols, phenols, ethers, aldehydes, ketones, esters,
peroxides, and organic acids (Roberts and Caserio, 1967).
Some minor amounts of oxygenated hydrocarbons are emit-
ted as solvent vapors from the chemical, paint and plastics
290
Table 5.1-5
Average Hydrocarbon Composition from
218 Ambient Air Samples Taken in Los
Angeles, California
Concentration
Compound
ppm
ppm (at carbon)
Methane
3 22
3.22
Ethane
0.09S
0.20
Propane
0.049
0.15
Isobutane
0 013
0.05
n-Butane
0 064
0.26
Isopentane
0 043
0.21
n-Pentanc
0.035
0.18
2,2-Dimethylbutane
0.0012
0 01
2,3-Dimethylbutane
0.014
0 08
Cyclopentane
0.004
0 02
3-Methylpentane
O.OOS
0.05
n-Hexane
0.012
0 07
Total alkanes (excluding methane)
0.3412
1 28
Ethylene
0 060
0 12
Propene
0.018
0.05
1-Butane + isobutylcne
0 007
0 03
(rons-2-Butene
0.0014
0.01
cw-2-Butene
0 0012
Negligible
1-Pentene
0.002
0 01
2-Methyl-l-butcnc
0.002
0 01
<rans-2-Pentenc
0.003
0.02
cts-2-Pentenc
0.0013
0.01
2-Methyl-2-butene
0 004
0.02
Propadiene
0 0001
Negligible
1,3-Butadicnc
0.002
0.01
Total alkenes
0 1020
0.29
Acetylene
0.039
O.OS
Methylacetylene
0.0014
Negligible
Total acetylenes
0.0404
0 OS
Benzene
0.032
0 19
Toluene
0.053
0 37
Total aromatirs
0.085
05C
Total
3.788G
5 43
291
Table 5.1-6
Ozone Levels Generated in Photooxidation of Various
Hydrocarbons with Oxides of Nitrogen
Hydrocarbon
Ozone level, ppm
Time, min
Isobutenc
1.00
28
2-Mcthyl-l,3-butadienc
OHO
45
fran*-2-Butene
0 73
35
3-Heptenc
0 72
60
2-Ethyl-l-buteno
0 72
80
1,3-Pentadiene
0 70
45
Propylene
0.68
75
1,3-Butadiene
0.65
45
2,3-Dimethyl-l,3-butadiene
0.65
45
2,3-Dimethyl-2-butene
0 64
70
1-Pentene
0.62
45
1-Butene
0.5K
45
eta-2-Butenr
0 55
35
2,4,4-Tnmethyl-2-pentene
0 55
50
1,5-Hexadienc
0.52
85
2-Methylpentanc
0.50
170
1 ,5-Cy clooctadiene
0 48
65
Cyclohexene
0 45
35
2-Methylheptane
0 45
180
2-Methyl-2-butene
0 45
38
2,2,4-Tnmethylpentanr
0.2G
80
3- Methyl pen lane
0 22
100
1,2-Butadiene
0 20
60
Cyclohexane
0.20
80
Pentane
0 18
100
Methane
0 0
—
• Hydrocarbon concentration (initial; 3 ppm , oxide of nitrogen (NO
or NOj, initial; 1 ppm.
292
1.5
10
0.5
0
1.5
1 0
05
0
20
1 5
1 0
05
0
10
05
1 1 1 I I I I l l
Chicago, Illinois .^•«»»
X
(May through August »nd October)
J I I I I I ' ' L_
St
T
Louis.
-I
Missour
T
\
1 1
— i r
1 1
^
T
i
~
•^
■
i
'
(May
-I
th
rough July
. September
. and October 1
_L
~
1—
Denver,
r 1 1
Colorado
1
— r-
'
T 1 1
— r
/ \
/
^
>s
"V.
^^•.
i
(January through March
iiii
May
September
i
. and October 1
J 1 L
_i_
- 1
Washington
1 1
(January
1 1
through April
-t r — i r
and August through Octobe')
iiii
-1
1—
-^
12
h
12
6
■ p m
1?
Local time
Figure 5.1-3
Nonmethane hydrocarbons as measured by
a flame ionization analyzer, averaged
by hour of day over several months for
various cities.
293
4 5 6
Total hyOrocjrtxxv PP">
10
Figure 5.1-4
Nonmethane hydrocarbon fraction to total hydrocarbon for selected
locations. O: Los Angeles, California, 1967; D: Azusa, California,
1967; A: Los Angeles, California, 1968; V: Los Angeles, Calif-
ornia, 1968---Sundays; + Brooklyn, New York, 1069; ■ Bayonne,
New Jersey, 1968
294
industries. The greater quantities of primary emissions are more
usually associated with the automobile. Table 5.1-7 (Seizinger
and Dimitriades, 1972) lists some typical oxygenates found in
automobile exhaust. The aldehydes are the preponderant oxygen-
ates in emissions but are emitted in minor amounts when compared
to hydrocarbon, carbon dioxide, carbon monoxide and nitrogen
oxide emissions. Many oxygenated compounds are formed as second-
ary products from photochemical reactions (Tuesday, 1971).
5.1.2.3 The Oxides of Carbon
Carbon Dioxide
Carbon dioxide is not generally considered an air2pollu-
tant. It is non-toxic, and immense quantities of it ( 10 tons)
are cycled through the biosphere annually (Robinson and Robbing,
1972). It is an essential ingredient of plant and animal life
cycles. Through photosynthesis, it is converted to plant tis-
sues; oxygen is produced as a by-product. Without photosynthe-
sis, the world's supply of oxygen would reduce drastically to
that formed by lightning and photolytic processes acting on water
(Mason, 1966; Riehl , 1972).
The concentration of carbon dioxide in air is variable
and depends upon whatever sources or sinks are present and such
factors as the growing season when plants tend to deplete the
amounts present. Callendar (1958) studied carbon dioxide meas-
urements from 1870 to 1955 (Figure 5.1-5). A nineteenth century
base value of 290 ppm was established and is generally accepted.
Present day values have been set at 320 ppm with an annual growth
rate of about 0.7 ppm (Robinson and Robbins, 1972).
Worldwide combustion of fossil fuel is a
of the relatively rapid increase in carbon dioxide
and Robbins (1972) have reviewed
of carbon dioxide. Table 5.1-8
projected to the year 2000. A
3 00% in emissions over those of
and Robbins (1972) assume that
dioxide emitted remains in the atmosphere. This
an increase to about 370 ppm.
phere. Robinson
sinks and effects
dioxide emissions
crease of nearly
dieted. Robinson
primary cause
in the atmos-
the sources ,
shows carbon
rel at i ve i n-
1965 is pre-
hal f the carbon
woul d resul t i n
295
Table 5.1-7
Oxygenates in Exhaust from Simple Hydrocarbon Fuels
Ozygrnatr
Concentration range, ppm"
Acelaldehyde
0.8-4 9
Propionaldehydc (+ acetone)'
2.3-14.0
Acrolein
0.2-5 3
Crotonaldehyde (+ toluene)'
0.1-7.0
TiRlaldehydc
<0 1-0.7
Bcnzaldchyde
<0 1-13.0
Tolualdehydc
<0. 1-2.6
Ethylbenzaldehydc
<0. 1-0.2
o-Hydroxybenzaldehydc (+ Cio aromatic)*
<0. 1-3.5
Acetone (+ propionaldehydc)'
2.3-14.0
Methyl ethyl ketone
<0.1-1 0
Methyl vinyl ketone (+ benzene)'
0 1-42 6
Methyl propyl (or iaopropyl) ketone
<0 1-0 8
3-Mcthy]-3-buten-2-one
<0 1-0 8
4-Methyl-3-penten-2-one
<0 1-1.5
Acetophenonc
<0. 1-0.4
Methanol
0 1-0 6
Ethanol
<0 1-0.6
Ci alcohol (+ Ci aromatic)'
<0 1-1.1
2-Buten-l-ol ( + C»H,(J)
<0 1-3 6
Benzyl alcohol
<0 1-0 6
Phenol -+- cresolfsj
<0. 1-6.7
2,2,4,4-Tetramethyltctrahydrofuran
<0.1-C 4
Benzofuran
<0 1-2 8
Methyl phenyl ether
<0 1
Methyl formate
<0 1-0 7
Nitromethane
<0. 8-5.0
C.H.O
<0 1
c»h«o
<0. 1-0.2
C,1I,0<>
<U 1-0 3
• Values represent concentration levels in exhaust from all test fuels
1 Data represent unresolved mixture of propionaldehydc ■+■ acetone Chroma-
tographic peak shape suppests acetone to be the predominant component.
' Toluene is the predominant component.
* The Cio aromatic hydrorarlton is the predominant component.
' Benzene is the predominant component.
' The aromatic hydrocarbon is the predominant component
296
340
320 -
I 310 -
d
u
300 (-
290
280
1870
-
1
1
1
T
T
— 1 1 1
1
/
/
/
'/ '
-
0
0 >
So
-
o ^r
-
-
0
O
O S
-
_o
0
19lh Century b»»
y»luf ■ 290 ppm
0
0
__L .
0
'
1 1 J
i
1
1890
1910 1930
Ye.r
1950
1970
Figure 5.1-5
Average C09 concentration in North Atlantic region 1870-1956
297
Table 5.1-8
Projected C02 Emissions: 1965-2000
Emissions, 10' tons
t'y((ir
1965
1970
1980
1990
£000
Coal
7.33
7.40
7 . 55
7.70
7 . 8.-.
Petroleum
4 03
5 . 28
H . 57
13.90
22 50
Natural gas
1 19
1 62
2 79
4.80
8.27
Incineration
0 4C
0.51
0 61
0.73
0 88
Wood fuel
0 68
0 68
0 68
0 68
0.68
Forest fires
0 39
0 39
0.39
0 39
0 39
Total
14 OS
15 88
20 59
28 20
40 57
Relative chanpe
100%
113 %
146%
200%
288 7c
298
Ulirrviolet Vmole
Infrared
60
Iff5
Iff3
1ffJ
T 1 1 1 1
.tlacfcbody radiation at 1000* K Qjly/rrunl
,t «im«rrrur l* km* radiation (3 A ry/min)
Dtraci baam eatar radiation
*i — it»'» aurfaoa (O ry/m>n)
Abaorption
of
0 1 0?
05 10 20 5 10 20
Wa»»l«r<orh . microm
SO 100
Figure 5.1-6
Spectra of Solar and Earth Radiation
299
greenhouse, effect. The temperature increase theoretically
resulting from an increase of concentration to 370 ppm would be
0.5 C (Manabe and Wetherald, 1967). In reality
energy balance is much more complicated. Water
absorbs strongly in the infrared, the amount of
reflect sunlight, and global atmospheric circulation
play important roles (Robinson and Robbins, 1972; Sellers, 1965).
An increase in the reflectivity of the earth's atmosphere caused
by an increase in suspended particulate matter (McCormick and
Ludwig, 1967) or an increase in cloud cover could offset the
warming tendency of carbon dioxide.
the earth ' s
vapor, which
clouds which
patterns al
Carbon Monoxide
Carbon monoxide is a colorless, odorless, and tasteless
gas which is slightly lighter than air. It is considered a
asphyxiant because it combines strongly with the hemo-
the blood and reduces the blood's ability to carry
cell tissues. Untold numbers of deaths have been
carbon monoxide in coal mines, fires and non-ventilated
healthy working person can work eight hours a day, 40
dangerous
gl obi n of
oxygen to
caused by
pi aces . A
hours a week, without noticeable adverse effects at carbon monox
ide concentrations of 25 ppm (the threshold limit value).
Carbon monoxide is a product of incomplete combustion of
carbon and its compounds. It is emitted by fossil fuel combus-
tion sources in greater quantities than all other pollutant
sources combined. Table 5.1-9 summarizes the estimates of emis-
sions in the United States (Cavender et al , 1973). The automo-
bile is by far the largest single pollution emission source.
Figure 5.1-7 shows that maximum carbon monoxide concentrations
found at eight Continuous Air Monitoring Program (CAMP) stations
in the United States (Chang and Weinstock, 1973).
The background concentration of carbon monoxide is
estimated from data gathered in the Pacific (Robinson and
Robbins, 1972; 1970) to be approximately 0.1 ppm. Table 5.1-10
300
Table 5.1-9
Estimates of Carbon Monoxide Emissions
(United States) 1940-1970 (106 tons/year)
Source category 1940 1960 1960 1968 1969 1970
Fuel combustion in 62 5.6 2.6 2.0 1.8 0.8
stationary sources
Transportation 34 9 55.4 83 5 113 0 112 0 111.0
Solid waste disposal 1.8 2.6 5.1 8.0 7.9 7.2
Industrial process losses 14.4 18.9 17.7 8.5 12 0 11.4
Agricultural burning 9.1 10 4 12.4 13.9 13 8 13.8
Miscellaneous 19.0 10 0 6.4 5.0 6 3 3.0
Total
85.4
103 0
128 0
150.0
154.0
147.0
Total controllable"
66 4
92 9
121.0
145 0
148 0
144 0
* Miscellaneous sources not included.
301
Cart plus truckt millions
Figure 5.1-7
Maximum CO concentrations at Continuous Air Monitoring Program
(CAMP) stations. 1962-196S maxima vs cars plus trucks. Denver
(Den.), Colorado; Cincinnati (Cin.), Ohio; Washington (Wash.),
D.C.; St. Louis (S.L.), Missouri; San Francisco (S.F.), California;
Philadelphia (Phil.), Pennsylvania; Chicago (Chi.), Illinois;
Los Angeles (L.A.), California.
302
Table 5.1-10
Carbon Monoxide Concentrations in Representative United States Cities
Hourly Maxima in ppm. 1962-1967
Yearly
maxima
Theoret
ical geometric
Highest
Lowest
mean (17, 61)
Chicago, Illinois
59
28
13.2
Cincinnati, Ohio
34
20
4.8
Denver, Colorado
55
40
6.7
Los Angeles, California
47
35
9.7
Philadelphia, Pennsylvania
54
37
6 9
St. Louis, Missouri
29
25
5.5
Ran Francisco, California
3S
22
4 R
Washington, DC.
41
25
3 5
303
shows the range of maximum hourly average values for the years of
1962-1967 for eight major United States cities (USEPA, 1970;
Faith and Atkisson, 1972). The theoretical geometric mean hourly
concentrations for the entire period are also shown. CO concen-
trations are more than ten times the level of concentrations of
other major pollutants.
5.1.3 The Gaseous Compounds of Sulfur
5.1.3.1 The Sulfur Oxides
If7
Sulfur forms a number of
oxides (SO,
and sul fur
SO
2 ' 2 JL'
tri oxide (ST)-, )
so3,
but only sulfur dioxide (SO-) and sulfur tr i oxide *"( St) 3 ) are
any importance as gaseous air pollutants. The peroxide, So0 7 »
has been suggested as existing in the lower stratosphere where a
layer of sulfate particles has been found (Bigg et al , 1970;
Junge and Manson 1961).
emitted with S0o at about
Sulfur trioxide is generally cmiwucu mm ^w-
l%-5% of the S02 concentration (Cholak et al , 1958; Tice, 1962).
A few industries such as sulfuric acid manufacturing, electro-
plating and phosphate fertilizer manufacturing may emit higher
relative amounts (USEPA, 1972). Sulfur trioxide rapidly combines
with water in air to form sulfuric acid (^SO^) which has a low
dew point. An aerosol or mist is easily formed, and S03 or FUSO*
haze and poor visibility in air
for S03 or HUSO* in air is quite
to be interpreted with some care
is frequently associated with
(Figure 5.1-8). The analysis
difficult, and the data have
(USEPA, 1972).
Sulfur dioxide is a colorless gas with a pungent, irri-
tating odor. Most people can detect it by taste at 0.3 to 1 ppm
(780 to 2620 ug/ni ). It is highly soluble in water: 11.3 gm/100
ml as compared to 0.169 gm/100 ml for carbon dioxide, forming
weakly acidic sulfurous acid ( H « S 0 - ) . In clean air, it oxidizes
slowly to sulfur trioxide. It is oxidized more readily by atmos-
pheric oxygen in aqueous aerosols. Heavy metal ions in solution
catalyze the reaction which stops when aerosols become acidic.
Atmospheric ammonia neutralizes the acid to form ammonium sul-
fate, which is commonly found in atmospheric particles (Johnstone
and Coughanowr, 1958, 1960). In moist air and in the presence of
nitrogen oxides, hydrocarbons, and particulates, sulfur dioxide
reacts much more rapidly (Urone, 1972; Urone and Schroeder,
1969).
Today, sulfur dioxide remains one of the major atmos-
pheric pollutants. Its worldwide emissions have been estimated
at 146 megatons/year by Robinson and Robbins (Table 5.1-2) and
more recently as 100 (150 as sulfate) megatons per year by
Kellogg et al . (1972) who predict emissions of about 275 megatons
per year for the year of 2000. Estimated United States sulfur
dioxide emissions for 1970 were 33.9 megatons (Table 5.1-11).
Fuel combustion and stationary sources and industrial emissions
accounted for 70% and 18% of this figure, respectively (Cavender,
304
10' 10"
Sulfuric •cid mijt concentration, pg m'
Figure 5.1-3
Calculated visibility (visual range) in miles at various sulfuric acid
mist concentrations and different relative humidities.
305
Table 5.1-11
Estimates of Sulfur Oxide Emissions (United States)
1940-1970 (106 tons/year)
Source category
1940
1950
1960
1968
1969
1970
Fuel combustion in
16 8
18.3
17.5
24 7
25 0
26.5
stationary sources
Transportation
0 7
1.0
0.7
1.1
1.1
1.0
Solid waste disposal
Neg"
0 1
0 1
0.1
0.2
0.1
Industrial process losses
3 8
4.2
4.7
5 1
5 9
6.0
Agricultural burning
Neg
Neg
Neg
Neg
Neg
Neg
Miscellaneous
0 2
0.2
0.3
0.3
0.2
0 3
Total
21.5
23.8
23 3
31.3
32.4
33 9
Total controllable'
21 3
23 6
23 0
31 0
32.2
33.6
• Negligible (less than 0.05 X 10* ton6/yearJ.
* Miscellaneous sources not included.
Table 5.1-12
Sulfur Dioxide Concentrations in Representative
'united States Cities Hourly Maxima, ppm, 1962-1967
Yearly maxima
High si Lowest
Theoretical geometric
mean (17, 61)
Chicago, Illinois
1 69
0.86
0.111
Cincinnati, Ohio
0 57
0 41
0 018
l)cnvcr, Colorado
0 36
0 17
0 014
Los Angeles, California
0.29
0.13
0 014
Philadelphia, Pennsylvania
1 03
0.66
0 oco
St. Louis, Missouri
0.96
0 . 55
0.031
San Francisco, California
0.26
0 11
0.006
Washington, DC.
0 .62
0.35
0.042
306
et al , 1973). Intensive efforts are being made to control sulfur
dioxide emissions by either removing sulfur from coal and oil or
removing sulfur dioxide at the combustion source (USEPA, 1969).
Ambient air concentrations of sulfur dioxide are rou-
tinely measured in many cities and have been the subject of a
large number of studies. Table 5.1-12 give typical data obtained
from the United States Continuous Air Monitoring Program (CAMP).
Figure 5.1-9 shows the frequency distribution of sulfur dioxide
measurements made in selected United States cities. An approxi-
mate log-normal distribution is shown by the straight portions of
the lines. This confirms to some extent the model developed by
Larsen and others (Larsen, 1969; USEPA, 1969; Larsen, 1971).
5.1.3.2 Reduced Sulfur Compounds
Hydrogen Sulfide
Hydrogen sulfide (H«S) is a toxic, foul smelling gas
well known for its rotten egglike odor. -It can be detected at
concentrations as low as 0.5 ppb (7 yg/m ) (A.D. Little, Inc.,
1968). Its natural emission sources include anaerobic biological
decay processes on land, in marshes and in the oceans. Volcanoes
and natural hot water springs also emit hydrogen sulfide. A
total of approximately 100 megatons (268 when expressed as sul-
fate) is estimated to be emitted in nature (Table 5.1-2) (Kellogg
et al , 1972). However this estimate has been made with strong
reservations. The analysis of very low concentrations in air is
subject to error because some of the hydrogen sulfide is oxidized
to sulfur dioxide during the sampling process (Kellogg et al ,
1972).
Approximately three megatons of HpS are estimated to be
emitted each year by pollution sources fRobinson and Robbins,
1972) (Table 5.1-2). One of the larger single sources is the
kraft pulp industry which uses a sulfide process to extract
cellulose from wood (Blosser, 1972). Because of the strong odor
of sulfides, such facilities can be detected by their odor 40
miles or more downwind, unless emissions are carefully con-
trolled. Other hydrogen sulfide pollution sources include the
rayon industry, coke ovens and the oil refining industry. The
processing of "sour" crude oil results in the emission of hydro-
gen sulfide and other volatile organic sulfides. Hydrogen sul-
fide emissions from industrial processes are sometimes used as
fuel for boilers or are released in burning flares. In either
case, they are burned to sulfur dioxide and emitted to the air.
Today, many modern refineries recover their sour gasses and
process them to form sulfuric acid or elemental sulfur (Faith et
al , 1965).
Hydrogen sulfide concent rat i ons
higher than 0.1 ppm (140 yg/m ). Cholak
nati air over a period of five years~and
sulfide to exceed 0.01 ppm (14 yg/m ).
in urban air are rarely
(1952) analyzed Cincin-
rarely found hydrogen
A s urvey in Houston ,
307
0 01 006 0 1 0? 05 1 2 5 10 20 X 40 50 60
PERCENT OF TIME CONCENTRATION IS EXCEEDED
Figure 5.1-9
Frequency distribution of sulfur dioxide levels in selected United States
cities, 1962-1967. v, Chicago, Illinois; ▼, Philadelphia, Pennsylvania;
D, St. Louis, Missouri; ■. Cincinnati, Ohio; O, Los Angeles, California;
#. San Francisco, California.
308
Texas showed average values of 0.02 ppm in the most highly pollu-
ted sectian of the city. The highest level
(390 yg/nT) (Faith and Atkisson, 1972; SRI
found relatively high levels in Windsor,
concentration of approximately 0.1 ppm and
(835 u g/V).
measured was 0.28 ppm
, 1957). Katz (1955)
Ontario with a mean
a maximum of 0.6 ppm
Hydrogen sulfide blackens lead-based paints. A level of
0.1 ppm is said to produce blackening of such paints within 1
hour (Faith and Atkisson, 1972). In air, hydrogen sulfide is
oxidized to sulfur dioxide within hours, adding to the ambient
sulfur dioxide level (Kellog et al , 1972).
Mercaptans and Sulfides
Other sulfur compounds that are of interest in air
pollution, principally because of their strong odors, are methyl
mercaptan (ChUSH), dimethyl sulfide (CH^SChU), dimethyl disulfide
(ChUSSCH-,), and their higher molecular homologs (Blosser, 1972).
They have odors similar to those emitted by skunks and rotting
cabbage. Total emissions of these compounds are unknown. A
number of studies have been concerned with their evaluation
(Schmall, 1972) and their measurement in air (Figure 5.1-10
(Rasmussen , 1972 ) .
5. 1.4
The Gaseous Compounds of Nitrogen
N.
whi ch
Nitrogen forms the very stable diatomic gas, no
makes up over 78% of the atmosphere and, fortunately, helps
temper the oxidative power of atmospheric oxygen. It also forms
a large number of gaseous and nongaseous compounds, many of which
are essential to living matter.
They are produced by such natural processes as bacterial
fixation, biological growth and decay, lightning, and forest and
grassland fires. To a lesser extent, but in higher local urban
concentrations, nitrogen compounds are produced by man through a
wide number of agricultural, domestic, and industrial activities.
In the reduced state, nitrogen forms such compounds as ammonia,
amides, amines, amino acids and nitriles. In the oxidized state,
it forms seven oxides and a large number of nitro, nitroso,
nitrite and nitrate derivatives (Cotton and Wilkinson, 1966).
5.1.4.1 The Oxides of Nitrogen
The oxides of nitrogen include nitrous oxide (N^O),
nitric oxide (NO), nitrogen dioxide (N0?), nitrogen trioxide
(N0o), nitrogen sesquioxide (N2O3), nitrogen tetroxide (NoO^),
and nitrogen pentoxide (NoOc)* 'hey and two of their hydrates,
nitrous acid ( H N 0 ~ ) and nitric oxide (NO), and nitrogen dioxide
(NOg) are found in appreciable quantities. The latter two, NO
and N02> are often analyzed together in air and are referred to
as "nitrogen oxides" and given the symbol "NO ". Nitrous oxide
309
100
s:
GC
40 -
K
'Hydrogen fcjlfirje
, Dimethyl fcjUiO*
J
D it>p t>^ v i Oiujii.cv
-i l I l
' i l i_
01?34£6789!0
MINUTES
Figure 5. 1-10
Sulfur Gases in Ambient Air, In-Situ Analysis
310
(N«0) is not included in the "NO " measurement, but it is pos-
sible for the higher oxides to be included if they happen to be
present (APHA, 1972).
concentrations of
methane, and the
minor surgery and
produces a loss of
di sappear . It i s
some conditions it
Nitrous oxide (N„0) is a colorless, slightly sweet,
nontoxic gas present in the natural environment in relatively
large amounts (0.25 ppm) when compared to the
the other trace gases except carbon dioxide,
noble gases. It is used as an anesthetic in
dentistry. When mixed with air and inhaled it
feeling. Its effects are not severe and soon
commonly called "laughing gas" because under
can cause those who inhale it to laugh violently. The major
natural source of nitrous oxide is biological activity in the
soil and possibly in the oceans. A worldwide production rate of
10 tons per year and a residence time of four years has been
estimated (Robinson and Robbins, 1972; Craig and Gordon, 1963).
Nitrous oxide has been associated with photochemical reactions in
the upper atmosphere (Bates and Hays, 1967), but because of its
low reactivity in the lower atmosphere it is largely ignored in
air pollution studies. There are no known significant pollution
sources (Robinson and Robbins, 1972).
As a pollutant, nitric oxide is produced largely by fue
combustion in both stationary and mobile sources such as the
automobile. In the high temperatures of the combustion zone,
nitrogen reacts with oxygen to form nitric oxide:
N,
NO
(5.1-1)
The reaction
temperatures,
completely to
is endothermic and proceeds to the right at high
At low temperatures, the equilibrium lies almost
the left, but the rate of recombination is extreme-
ly slow. Consequently, the amount of NO emitted is a function of
the flame structure and temperature as well as the rate at which
the combustion mixture cools. If the cooling rate is rapid,
equilibrium is not maintained and the NO concentration, although
thermodynami cal ly unstable, remains high (Trayser and Creswick,
1970; Hall and Blacet, 1952). The proper catalyst can, of
course, expedite its decomposition to nitrogen and oxygen. In
exhaust gases, where higher concentrations and temperatures
311
prevail, some of the nitric oxide is oxidized to nitrogen diox-
ide. This generally varies from 0.5% to 10% of the nitric oxide
present (USEPA, 1971).
oxide
aut om
used
tures
hydro
oxide
m i x t u
the n
than
exces
tons
est im
State
accou
year
mum h
Figure 5.1-11 shows the relative amounts of nitrogen
s, hydrocarbons, and carbon monoxide in the exhaust of an
obile as a function of the ratio of the air-to-fuel mixture
for the engine. At low air-to-fuel ratios ("rich" mix-
), flame temperatures are low, combustion is incomplete,
carbon and carbon monoxide emissions are high, and nitrogen
s emissions are low. At higher air-to-fuel ratios ("lean"
res) the temperature of the combustion flame becomes hotter,
itrogen oxides increase until the air-fuel ratio is greater
the stoichiometric point and then decrease rapidly as the
s air cools the flame (Trayser and Creswick, 1970).
Worldwide pollution
per year of NO and N0?
sources emit
combined (NO
NO emission's expressed as
s. Fuel combustion in stationary
approximately 53 X 10
) . Tabl e 5.1-13 gives
NOo for the United
transportat i on
emitted per
Table 5.1-14 shows maximum and mini-
in several United States cities.
sources fiand
nt for more than 95% of the 22.7 X 10 tons
i n the Uni ted States .
our! y averages of NO
In a polluted atmosphere, nitric oxide is oxidized to
nitrogen dioxide primarily through photochemical secondary reac-
tions. Figure 5.1-12 shows the diurnal variations of NO, N02 and
0o in a typical photochemical pollution situation. Nitric oxide
reaches a maximum during the early morning traffic rush hours.
The rising sun initiates a series of photochemical reactions
which convert the nitric oxide to nitrogen dioxide. Within a few
hours the nitrogen dioxide reaches a maximum during which it
photochemi ca 1 1 y reacts to form ozone and other oxidants. Both
the nitrogen dioxide and the ozone eventually disappear through
the formation of nitrated organic compounds, peroxides, aerosols,
and other terminal products. The cycle is repeated the following
day. If the air mass is not swept away or is brought back by a
reversing wind, the residual gases add to the new day's pollu-
tants (Tuesday, 1971).
Nitrogen dioxide is a redd i sh- brown gas with a pungent,
irritating odor. At concentrations higher than those found in
the atmosphere, it forms a colorless dimer, nitrogen tetroxide
(N?0.). Natural emissions are due primarily to biological decay
involving nitrates being reduced to nitrites, followed by conver-
sion to nitrous acid (HNOo). decomposition to nitric oxide and
oxidation to ryitrogen dioxride. Natural emissions are estimated
to be 658 X 10 tons per year.
Nitrogen dioxide is one of the more invidious pollu-
tants. It is irritating and corrosive in itself, but more im-
portantly, it serves as an energy trap by absorbing sunlight to
form nitric oxide and atomic oxygen:
312
— I 1 I —
I
STOICHIOMETRIC
10
14 16 IB
AIR-FUEL RATIO
22
Figure 5.1-11
Effects of air-fuel ratio on exhaust composition
(approximate ranges, not to scale).
313
Table 5.1-13
Estimates of Nitrogen Oxide (NO ) Emissions
(United States), 1940-1970 (106 tons/year)
Source category
191,0
1950
I960
196S
1969
1970
Fuel combustion in
3 5
4
3
5 2
9 7
10 2
10 0
stationary sources
Transportation
3 2
.">
2
s o
10.6
112
11 7
Solid waste dispos.il
0 1
0
2
0 2
0 4
0 4
0 4
Industrial process Itwtsc*
Neg°
0
1
0 1
0 2
0 2
0.2
Agricultural burninc
0 2
0
• )
0 3
0 3
0 3
0.3
Miscellaneous
0 K
0
4
0 2
0 2
0 2
0 1
Total
7.9
1(1
4
14 0
21 3
22 5
22 7
Total controllable'
7 1
10
0
13 R
21 1
22 3
22 6
"Negligible (less than 0.0.1 X 10' ton.- year J
s Miscellaneous sourro not included
Table 5.1-14
Nitrogen Oxide (NO ) Concentrations in Representative
United States Cities Hourly Maxima, ppm, 1962-1968
Yearly
maxima
Geometric
Highest
Lowest
mean
Chicago, Illinois
1.06
0.69
0.75
Cincinnati, Ohio
1 42
0 4')
0 S3
Denver, Colorado"
0.72
0.56
0.62
Los Anfreles, California
1.35
0 98
1.24
Philadelphia, Pennsy
Ivania
1.79
0.97
1.53
St. Louis, Missouri'
0 92
0 44
O.o7
Washington, D.C.
1 30
0.68
0 83
• 1 965-1 96 ^
♦ 1964-1968
314
•
Hour of d»v
it..
Figure 5
Typical diurnal variation of NO, N02, and O3 concentrations in
Los Angeles, California. Solid line, ozone; long dashed line,
nitrogen dioxide; dotted line, nitric oxide.
40000 KOOO
KOOO KOOO
*lSOl.V(D ABSOO'HON S*(CT««» Of NO. »NDN,0.
^^h^^^_
JbOO «0X
Figure 5.1-13
Absorption coefficients (1/pl log1Q |Q/|) of N02 and N204
vs wavelength and wave number, measured at 25^C.
315
N02 +
hv
NO
0
(5.1-2)
The
and
t i on
bl ue
Figu
trum
cate
- mi
ppm
more
the
more
hove
and
atomic oxygen is very reactive, forming ozone with oxygen,
initiating a number of secondary photochemical chain reac-
s. Nitrogen dioxide absorbs light strongly in the yellow to
end of the visible spectrum and the near ultraviolet.
re 5.1-13 (Hall and Blacet, 1952) shows the absorption spec-
of nitrogen dioxide, and Figure 5.1-14 (USEPA, 1971) indi-
s the amount of light absorbed in terms of parts per million
A mile thick layer of air containing 0.1
ultraviolet light reaching the ground by
through a horizontal layer of 10 miles,
reduces the blue and ultraviolet light
.1-14). The yellow-brown haze often seen
in a large part due to nitrogen dioxide
the aerosols it helps generate (Carlson and Ahlquist, 1969).
le concentrations,
of N0? reduces the
than 25%. Viewed
same concentration
than 90% (Figure 5
ring over a city is
have
t i on
Gay
monl
diff
var i
1 yze
vapo
spec
trat
from
meas
pher
repo
Nitrogen trioxide ( N 0 3 ) and nitrogen pentoxide ( N ? ^ 5 )
been postulated as intermediates in the photochemical oxida-
of hydrocarbons and sulfur dioxide (Urone, 1972; Louw, 1973;
and Bufalini, 1971; Schuck et al , 1966). They are not com-
y observed; their concentrations are expected to be small and
icult to measure in air in the presence of NO, N0~ and their
ous photochemical reaction products. The pentoxide hydro-
s readily with water vapor in the air to
r (HN(K) which has been detected in the
troscopic means (Cadle and Allen, 1970).
e (PAN), an eye- i rr i tat i ng photochemical
hydrocarbons and nitrogen oxides, has been
ured in air (Hall and Blacet, 1952; Hanst,
ic concentrations as high as 0.1 ppm (500 yg/md) have been
rted (JSEPA, 1971).
form nitric acid
stratosphere by
Peroxyacetyl ni-
reaction product
identified and
19731). Atmos-
5. 1.5
Ozone and Ox i dant s
Ozone, O3, is a bluish gas about 1.6 times as heavy as
air and highly reactive. It is formed at high altitudes by
photochemical reactions involving molecular and atomic oxygen
(Cotton and Wilkinson, 1966). Its concentration in the atmos-
phere depends upon the altitude; being greatest in the stratos-
phere. At 20 km, its concentration is 0.20 ppm. Its concentra-
tion in rural areas, away from pollution sources, is approxi-
mately 0.02 ppm (USEPA, 1970). Very minor amounts of ozone are
formed during lightning and thunderstorms. Ozone strongly ab-
sorbs ultraviolet light in the wavelength region of 2000-3500 A
and very weakly at about 6000 A. Its absorption of the energetic
portion of the ultraviolet light prevents serious damage to
living tissues (USEPA, 1970).
Ozone and other oxidants
and hydrogen peroxide (Bufalini et
luted atmospheres as a result of a
chemical reactions (Tuesday, 1971;
levels have been found not only in
such as PAN (Stephens, 1961)
al , 1972) are formed in pol-
rather wide variety of photo-
Leighton, 1961). High ozone
urban areas, where it follows
316
80
_
1 1 1___
60
0 1 ppm ■ mile
f _
50
-
40
-
30
-
20
-
10
_
8
-
6
Ippm-miie /
-
5
-
4
1
3 ppm- mile /
1 1 / 1
/ 10 ppm - mile
/ I 1
-
3600 4000 4500 5000 5500 6000 6500 7000
VIOLET BLUE GREEN YELLOW ORANGE RED
WAVELENGTH. A
Figure 5.1-14
Transmittance of Visible Light at Different N02
Concentrations and Viewing Distances
317
a trend of build-up during the day
night, but also in rural areas. It is
precursors are being transported long
be a nautral source within rural areas
and break-down during the
believed that ozone or its
distances or there may may
The overall effect of ozone is a stinging of the eyes
and mucous membranes. This reaction was first noticed in Pasa-
dena, California, a suburb of Los Angeles. Shortly thereafter,
polluted atmospheres were labeled as "Los Angeles" type because
of their general oxidative character. "London" (England) type
smogs (i.e., smoke plus fog) were reductive in nature because of
their higher concentrations of sulfur dioxide and soot from the
burning of coal. Figure 5.1-12 shows the diurnal variation of
nitrogen oxides and ozone in a typical Los Angeles type of photo-
chemical pollution. However, since London has cleared its air
with a vigorous smoke abatement program, it is experiencing Los
Angeles type of pollution as shown by Figure 5.1-15 (Derwent and
Stewart, 1973).
To prevent possible serious health effects, an ambient
air quality standard maximum 1-hour concentration of 240 9/m3
(C.12 ppm) has been adopted. Alert levels were set at 200 g/m
(0.1 ppm). Figure 5.1-16 shows the number of times that the
alert level was exceeded in Los Angeles, California for 1967 thru
1971 (Sagersky, 1973). A study of oxidant levels in the San
Francisco, California Bay Area show a trend to smaller annual
oxidant levels (Cramer, 1973). However greater efforts are
needed to reduce these values. Two studies have shown that
indoor air follows outdoor air concentrations rather closely
(Mueller, et al, 1973; Thompson et al, 1973).
A number of areas have been measuring total oxidant and
ozone concentrations above the alert levels (USEPA). There is
reason to believe that the "oxidative" conditions in these in-
stances are not the same as those found in larger cities. Rip-
perton, et al. (1971), for example, have found evidence for
tropospheric photochemical production of ozone.
Chesick (1972) and others (IDA, 1973) have been con-
cerned over the effect that high-flying jet planes would have on
the upper atmosphere. Water vapor and nitrogen oxides emitted
from the jet exhausts conceivably could react with ozone and
reduce its insulating quality for strong ultra-violet rays.
5.1.6
Pa rt i cul ate Matter
The particulate matter commonly found dispersed in the
atmosphere is composed of many substances: flour ides, beryllium,
lead, and asbestos (all toxic), aerosols, dust and other matter
such as wood waste generated by forest fires. Combustion also
produces particles. Particles larger than 10 m result from many
mechanical processes such as wind erosion, grinding and spraying.
Trees produce terpenes which can result in organic particles and
oceans produce salt particles as well. Only three general class-
es of physical properties can reasonably be said to apply to all
particulate matter. These properties all involve the interface
318
00 04 08 12 16 20 00 CM 08 12 16 20 00 04 08 12 16 20 00
July 12. 1972 July 13, 1972 July 14 1972
Time of day
Figure 5.1-15
Diurnal variations of air pollutants measured in London, England from
July 12 to July 14, 1972. ■, Ozone, ppb; #. nitric oxide, ppb;
□ , nitrogen dioxide, ppb; O, hydrocarbons, ppm.
319
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
MONTH
Figure 5.1-16
The number of days each month in Los Angeles
County, California during which the ozone
concentration has risen to 0.1 ppm or above.
Solid line: 1967; short dashed line: 1968;
long dashed line: 1969, dashed-dotted line:
1970; dotted line: 1971.
320
between particles and their surroundings, and include (1) surface
properties, (2) motion, and (3) optical properties.
Surface properties include sorption, nucleation and
adhesion, among others. Sorption is the deposition of molecules
due to collision with an object. If the molecules are in a
supersaturated atmosphere, the deposited molecules can attract
other molecules causing them to condense out around the original
deposit. This is nucleation.
Optical properties cover the behavior of particles
toward light. This affects visiblity, particularly when par-
ticles larger than 1 urn are involved. These particles intercept
or scatter light in proportion to their cross- sect i onal area.
Smaller particles also scatter light, but according to far more
complicated scattering laws.
The concentration of~suspended particulate matter
ranges from less than 60ug/m to 1700 ug/m in various Ame
cities often shows a notable annual variation. Levels are 1
in summer and highest in autumn and winter. Losses of
radiation occur due to these concentrations, and can run as
as one-third in the summer and two-thirds in the winter,
is also a correlation between particle concentrations and
fall, and particulates and visibility. The EPA is pres
considering a standard for fine particulates which are felt
the most important in terms of (1) the respirable fraction
the catalytic conversion to secondary contaminants and (3)
bi 1 i ty impai rment .
whi ch
ri can
owest
sol ar
high
There
rai n-
ently
to be
, (2)
vi si -
Although raw auto exhaust contains some particulate
matter (smoke particles), this is not sufficient to degrade
visibility significantly when diluted several thousandfold with
air. However, aerosols can be formed by irradiation of dilute
auto exhaust or of hydrocarbon/NO mixtures. Aerosol formation
is much enhanced by the addition of sulfur dioxide to the mix-
ture. This suggests that sulfuric acid plays a role since H^SO.
is not only \/ery nonvolatile but it also will absorb water.
5.1.7
Atmospheric Chemistry of Air Pollution
The solution of many air pollution problems involves
knowledge of the chemistry of the atmosphere, when it may be
termed "clean" and when it is "dirty." Also, the nature of air
321
pollutants as they react as a whole must be determined. In
general, the two classes of polluted smogs are called either the
London type - a reducing smog where contaminants form nuclei for
condensation of water vapor into fogs--or the Los Angeles type -
an oxidizing smog where contaminants are photolysed to irritants.
• Solar Radiation
boj
The sun approaches a perfect black body
closely in the region of 6000°K (12,}00°F).
radiator most
Its maximum
energy per wavelength occurs at04500A, while its maximum
photon emission occurs at 6 0 00 A. Photons produce many
chemical and energy changes in matter at the molecular
level upon absorption, by upsetting vibrational, rota-
tional and electronic balance. Vibrational and rota-
tional changes occur mainly in the infrared region while
electronic shifts need the higher energy of the ultra-
violet range.
Photochemical Reactions
There are four
which occur in
sorption, ( 3 )
react i ons . We
absorb photons
bl e range ) .
Absorbers
main steps in a photochemical reaction
time sequence: (1) Radiation, (2) Ab-
Primary Reactions, and (4) Secondary
are mainly interested in substances which
in the 3000-7000A spectral region (visi-
Non- absorbers
j
j
N(
SOp
Hn6? - HNO.
rch6 -*
RCO
RCOO
Parti cul ates
N2
CO
CO-
N(r
SO-, -
RCR
RCOH
RCOOH
H2S04
(R denotes a rad i cal )
Oxygen
The most important photochemical reactions involve the
very reactive single oxygen atom.
0
0
J
J
0
0
OLEFINS — ►Several Fragments
NO
SO
NO
SO
0
322
These atoms are produced by two main reactions
N02 + hv
0, + hv
NO + 0
Major fragments of photO'
chemical reaction in the
atmosphere where h •
Plank's constant and v
the frequency of
t i on .
the radi a
1
Oxygen atoms are produced at the rate of 150 pphm hr'
but because of their reactivity, their stationary con-
centration in air is usually only 1-2 ppht (parts per
hundred thousand) .
Ozone
Ozone is yery important as a reactant in photochemical
type smog. It is produced through the photolysis of
nitrogen dioxide and the reactive oxygen atom.
NO,
0
hv
0o
NO
0-,
0
Ozone is a strong oxidizer and its main atmospheric
reactions are:
90%
Equal Rate
Sulfur Dioxide
0
NO
NO
■NO
2
NO.
0
01 ef i ns -►Free radicals,
other organic fragments
Sulfur dioxide is the major sulfur containing compound
formed during fuel combustion. Hydrogen sulfide is easily oxi-
dized to sulfur dioxide in air, especially in the presence of
sunlight. In sunlight, sulfur dioxide reacts with either atomic
or molecular oxygen to form an aerosol, particularly if water
vapor is present. This aerosol is dilute sulfuric acid when
uncontaminated with particulates, which are found in reducing
type smogs. Sulfur dioxide also reacts with organics to form
various sulfonic acids which are also irritants. Relative humid-
ity plays a very important role in the photochemical reactions of
sulfur dioxide by determining part i cul ate-aerosol formations.
Organic Compound Reactions
The range of classes of organic compounds emitted from
various processes and industries is very wide. Most of the
higher molecular weight products settle rapidly, but short carbon
323
chain molecules tend to be more reactive as ionic character
outweighs the usual covalent nature of organic materials and they
are very important as irritant precursors. Absorption of photons
often leads to dissociation into free radicals - short fragments
with extra electrons which are extremely reactive. Olefins,
aldehydes, ketones, peroxides, are classes which easily absorb
photons and form free radicals, and are among the usual products
of combustion, especially from oil base fuels.
Nitrogen Oxide Reactions
Oxides of nitrogen are formed in practically all combus-
tion processes in air, but the diurnal peaks and valleys of
concentration are a matter of concern in air pollution studies
due to the high buildup in the morning hours within urban areas
as vehicular traffic reaches a peak. The sequence of reactions
NO
NO
hv
0
2
0
NO
°3
NO
0
2
0
is the fastest, most important, and results in the highest con-
centrations of actual and potential irritant concentrations in
air pollution - atmospheric chemistry. Second in importance,
photochemically, is olefin photolysis and ozone - organic mole-
cule interaction. Other nitrogen oxide reactions of less im-
portance are :
N02 +
NO +
N2°5 + H20-*-2HN03
Non-photochemical Reactions
A secondary reaction following photochemical reaction
which is very important is :
On + Olefins -^-free radical fragments
Olefins are the most important beginning class of organic com-
pounds for production of irritants and phytotox i cants .
Reaction with water vapor:
NOx + H2°"*"HN02 " HN03
S03 + H20-»-H2S04
324
Other inorganic and organic classes of compounds are
also emitted to the atmosphere such as flourides which quickly
react with various surfaces, ammonia which forms acids, hydrogen
sulfide which reacts with organics and forms sulfates, carbon
monoxide which slowly oxidizes to carbon dioxide and organic
amines which oxidize to acids. The above reactions are generally
not of importance except in small localized areas.
Particulate Material Reactions
Particulate matter consists of an entirely different
size category than we have examined thus far. As such, it pro-
vides reactive surfaces and can act as a third body and catalyst.
Interaction with a particulate surface can cause either an energy
level change or complete chemical change.
Examples of the former are:
*■ M-*^0^22 + M Change in absorption
0X12
CH3 +
M
CHn + M Termination of free radical
Examples of the latter are
Zn 0(M) + H20 vapor-^
where :
-H202 +
X = is the wavelength and
M = represents an energy- accept i ng third body
Catalyzed by photons
S02 + H20 drop — »
■H2S03
drop
H2S04» H20 drop + Ca C03-»-CaS04 + C02 + H20 Change
i n part icul ate
Kinetics in Atmospheric Chemistry
Without becoming involved in the rigors of kinetic
theory, a few elementary definitions should be stated. The basis
for determining the importance of any photochemical reaction,
stationary concentration, rate of reaction, etc., is the Stark-
Einstein Law which states that one photon must be absorbed to
ini ti ate photol ysi s.
equat i on :
From
this
I
theory is derived the important
Where k is the specific absorption rate,
of absorption, j is a conversion factor,
tion of the absorbing substance. k
I is the rate
and c is the concentra-
represents the average
fraction of absorbing molecules which receive photons per unit
325
is given by :
time. Primary quantum yield is very important as it tells us
what percent of molecules that absorb photons will acutally react
to the absorbed energy via a specific process. Absorption of a
may result either in energy level change, shown by flores-
or chemical change, shown by dissociation or direct reac-
The rate of formation of excited molecules A
d (A1).
1 a a
c, the concentration of the absorber.
For secondary photochemical reactions rate
important. For a bimolecular reaction A + B — ►C
decrease in concentration of A will be:
photon
cence ,
t i on .
(A)
dt
= I = k (A) =
kac
where
constant
+ D,
1 s
the
d (A) _
dt
kj (A) (B)
where K, is the rate constant of the reaction. In general, the
larger the rate constant, the more probable and more important
part the reaction plays in the atmosphere.
Thus, a knowledge of what general reactions take p
in the atmosphere under different meterol og i cal conditions,
help answer questions concerning the relative importance
contaminating substances. From a meteorological point of v
relative humidity and percent possible sunshine are the
important parameters to consider. This is because nitr
dioxide- ol efi n photolysis and the reactions which follow
sunshine dependent and the sulfur di ox i de- part i c u 1 ate react
are largely humidity dependent. Further consideration invo
precipitation which functions as a removal method, and low
speed which causes the atmosphere to function as a stable r
tion vessel. Extremes of temperature either help catalyze ph
chemical reactions, as in los Angeles, or enhance fog forma
1 ace
can
of
i ew ,
most
ogen
are
ions
1 ves
wi nd
eac-
oto-
t i on
of part icul ate
S0? reactions, as in London.
The state of knowledge of atmospheric chemical reactions
and interactions leaves a good bit to be desired as the subject
is ^ery complex. Experiments in all the areas discussed are
increasing our knowledge and the total picture is slowly
emergi ng .
326
5.2
AIR POLLUTION EFFECTS ON AIR QUALITY RELATED VALUES
A pollutant can be roughly defined as a harmful chemical
or waste material which is discharged into the atmosphere or
water. Pollutants add stress to the biosphere, thereby affecting
the quantity, quality or diversification of populations. State
and local governments have regulated air pollutants for many
years, but the first federal legislation was not seen until 1955,
with the establishment of an air pollution research program.
Public awareness of air pollutant hazards has increased tremen-
dously since that time, and culminated in the enactment of the
1977 Clean Air Act Amendments. As stated in the Act, the purpose
of this legislation is "to protect and enhance the quality of the
Nation's air resources so as to promote the public health and
welfare" (CAAA, 1977). Falling under the umbrella of public
health and welfare is not only man, but all air quality related
values, including soils, vegetation, wildlife, watersheds, arch-
aeology, and visibility. In general, all aquatic and terrestrial
flora and fauna and their habitats must be evaluated to determine
threshhold levels, or the point at which a pollutant can no
longer be tolerated by a population. Section 5.1 detailed the
formation of air pollutants. This section will describe the
effect of these pollutants on the environment.
As depicted in Section 2, the majority of BLM lands are
situated within the 500-3000 foot elevation range; however, areas
as low as sea level and as high as 6000 feet are also found
within the Ukiah District. The major vegetation types concen-
trated in these areas include redwood, Douglas fir, fir, pine,
woodland, plains grass, chaparral, saltbush and marsh. While
pollutant effects have been felt severely by California's agri-
cultural crops, these will not be discussed to the extent of the
aforementioned vegetation types, as they are not of primary
importance to the BLM. Effects on fisheries and native animals
will also be discussed to the extent that they have been re-
searched. It is also valuable to note that effects of air pol-
lutants have been seen in arc heol og i c a 1 sites, such as ancient
Grecian ruins, and in geology throughout Europe and the Eastern
United States. Although these later effects have not been seen
or researched in California, they may become a serious future
concern .
Part i cul ates
Within the BLM lands in the Ukiah district, man-made
emission densities for particulates range from 0-12,000 tons per
year, with the highest emissions density being found in Humboldt
County. Particulates may be defined as dispersed matter in the
liquid or solid phase. A few of the wide variety of chemical
constituents of particulate matter are listed in Table 5.2-1.
Individual particles range from 0.005 to 500 ym in diameter.
While emission control devices can remove up to 99% of stack
particulate emissions, their efficiency becomes considerably
327
lower for particles in the size range of 0-5 urn. These parti-
cles, therefore, are more readily emitted and can be transported
over great distances. Also, this size range is easily passed
into the lungs of man and animals, making these smaller particles
the most deleterious.
The effect that particulate matter will evoke depends
largely on its chemical composition. In general, most trace
elements deposited on soil will remain in the surface layers,
except in very acidic or sandy soils. While this accumulation
serves to protect groundwaters from contamination in the short
term, in time, natural processes such as surface runoff, erosion,
and windblown dust may serve to contaminate aquatic biota. One
of the most important factors in determining potential soil
effects is the concentration of naturally occurring endogenous
trace elements. Impacts of added particulates will be more
severe in areas where endogenous concentrations are currently
close to the tolerance limit for any population member. On the
other hand, benefit in a deficient area may be gained by the
addition of essential trace elements, such as copper, boron,
molybdenum, zinc and manganese, (Dvorak, 1978).
Effects on vegetation will ^ary considerably. Visible
effects range from chlorosis, necrosis and discoloration to
stunting and deformation. These may be linked to changes in
enzymatic reactions or metabolic processes, such as photosynthe-
sis and respiration and will depend not only on the chemical
composition of the particulate matter, but also on the exposure
concentration, and plant species. In a natural vegetation area,
such as the forests of the Ukiah District, where the majority of
the vegetation is recycled rather than consumed, concentration
build-up will exceed that found in agricultural areas.
As trace elements collect in the edible plants the
entire food chain will be impacted. Herbivorous wildlife are
affected through ingestion and also by the loss of sensitive
plant species within their habitat. These factors may contribute
to reduced numbers of wildlife species or possibly the elimina-
tion of certain species from the affected environment. Inges-
tion, along with inhalation, are the two modes of entry of trace
elements into animals. Several effects of these elements are
detailed in Table 5.2-1.
Sulfur Dioxide
All areas monitoring SO? levels within the Ukiah Dis-
trict have S02 concentrations below one-tenth pphm as shown in
Figure 5.3-7 and are classified either as better than national
standards or unclassified. However, this cl ass i f i cai ton does not
preclude effects from being seen within this area. Sources of
SO? and sulfur compounds include high sulfur fuel combustion
(SO?), anaerobic decompostion of plants material (H?S), and the
industrial production of sulfuric acid. Coal-fired power plants
alone account for 40% of total U.S. sulfur-compound emissions.
328
Table 5.2-1
General Manifestations of Trace Elements in Animals
Target organs or characteristics
Element
of toxicity
Comments
Arsenic
Has been associated with increased
Non-accumulative in animals but has
incidence of lung cancer.
affinity for hair, nails, and skin.
Bar- ..
Has strong stimulating effect on all
Poorly absorbed with generally little
muscles in acute poisoning.
retention in tissue.
Beryll ium
Characteristic granuloniatous changes of
Via inhalation, beryllium is corre-
lung tissue is brought about by long-
lated with an interference in the
term exposure.
passage of oxygen.
CdC-
Is linked with the incidence of hyper-
Accumulative in all animals and toxic
tension in experimental animals.
to all systems and functions in humans
and animals.
Cobal t
Causes changes in lungs typical of
With increasing age, the body burden
pneumoconiosis. Also causes induction
of cobal t diminishes .
of polycythemia in many species.
Copper
Associated with induction of haemolytic
In excess, results in some accumulation
disease, especially in certain species.
in the tissue, especially in the liver.
Chrc " j
hexavalent corpounds extremely toxic to
In particular, the respiratory tract
body tissue. Insolutle forms retained
and fat tissue accumulate this metal.
in lung tissue.
Fluoride
Contributes to dental fluorosis in
2 n i ma 1 s .
Deposits in bone tissue.
Lead
".-;.'.. absorbed lead is mostly retained
Has strong affinity to accumulate in
in trie body as lead triphosphate, espe-
bone tissue.
cia"" liver, kidneys, pancreas,
and aoi "
Manganese
Acute intoxication involves changes in
Most amounts taken into the body are
the respiratory system, whereas chronic
retained, especially in liver and
poisoning affects the central nervous
lymph nodes.
system.
Mercury
Organic forms have effects on brain
Can bioaccumulate in tissues of
tissue. The inorganic form is more
animal s.
linked to damage to liver and kidneys.
1
Associated with degenerative changes
in 1 iver eel 1 s.
Can accumulate in tissues.
Nicl
Associated with cancer of lungs.
Very poorly absorbed from gut.
Selenium
Associated with alkali disease in
Is converted in the body into a
cattle.
volatile compound which is eliminated
through breatn and sweat.
Vanadiu
Is found to inhibit the synthesis of
Vanadium salts are poorly absorbed
cholesterol and other lipids. Other
from the gastrointestinal tract.
compl ications leading to cardiovas-
cular diseases are also prevalent.
Zi nc
Intoxication produces either lung or
Absorbed or injected zinc is incor-
intestinal tract manifestations.
porated at varying rates into dif-
ferent tissue, indicating varying
— — _ — _____
rates of zinc turnover.
Source: Dvorak, 1978
329
Highest levels of exposure from such plants may be expected in
the Western U.S., where scrubbers are not used (Dvorak, 1977).
Since many BLM land areas contain major coal reserves, this may
be an area of great concern in the future.
The effects of gaseous air pollutants such as S0~ on
plants and animals are typically classified according to the
exposure. Acute effects are those related to exposures of short
duration (up to one month) and comparatively high concentrations.
Chronic effects are evoked when organisms are exposed to low-
level concentrations for periods of one month to several years.
Long-term effects are the result of exposures lasting for decades
or longer. These are characterized by abnormal changes in the
ecosystem or subtle physiological changes in the organism. Acute
injury to vegetation from SOo exposured is characterized by
collapsed marginal or intercostal leaf areas, which later become
dried and bleached to an ivory color in many species, or brownish
red or brown in other species. Chronic injury is seen as leaf
yellowing from the margins to intercostal areas. Both acute and
chronic injuries can result in death of the plant. Long-term
injury may also occur without visible symptoms, but may be im-
plied by subtle changes in the ecosystem (Dvorak, 1976).
Sensitivity to SO,-, will vary according to the plant
species and microclimate in which it exists. Several vegetation
types native to BLM lands in the Ukiah District have been listed
in Table 5.2-2, according to the sensitivity level as determined
by the reference. Plants may also be affected in the following
ways: increased respiration, decreased protein content and
metabolism, decreased sugar, vitamin and starch content, de-
creased glucosidase activity and altered terpene activity.
Studies
and S0o with N0o effects
on
concerning S0? u..u ^w~ », iuh mw~
desert-type vegetation of the Southwestern U.S. have been con-
ducted by Hill, et.al. (1974). The area studied included Utah
and New Mexico at elevations of 4500 to 6500 feet. Using con-
centrations of 0.5 to 11 ppm S0o + 0*1 to 5 ppm N 0 « for 2-hour
fumigation periods, the study ranked sensitivity according to
Table 5.2-3. Studies have been ranked together as no synergistic
effects were found. Common injuries appeared as leaf necrosis
and interveinal patches of necrotic tissue on broad leaves.
Color of injured tissue varied from tan, gray brown and yellow to
rusty brown depending on the species. With desert plants, often
the entire leaf was injured. Results of the study suggested that
middle-aged and older leaves were more sensitive than younger,
expanding leaves and years with unusually high rainfall could
cause more severe injury to desert type vegetation (Hill, 1974).
Caldwell, et al (1976) also studied S02 effects on
southwestern U.S. desert vegetation. Fumigation studies were
conducted in the Catalina Mountains near Tucson at 7700 ft.
Results were similar to those by Hill, et . al . (1974); however,
Caldwell noted that SO- will injure vegetation to a maximum
distance of 30 to 40 miles. Past that point, the plume will be
330
Table 5.2-2
SCL Injury to California Native Vegetation
Common Name
Sensitivity
Reference
Pine, Jack & Red
Sensitive
Davi
s & Wilhour
(1976)
Douglas Fir
Intermediate
Dav
s & Wilhour
(1976)
Fir, Basalm & Grand
Intermediate
Dav
s & Wilhour
(1976)
Pine, Lodgepole
Intermediate
Dav
s & Wil hour
(1976)
Pine, Ponderosa
Intermediate
Dav
s & Wilhour
(1976)
Pine, Western White
Intermediate
Dav1
s & Wilhour
(1976)
Fir, Silver
Resistant
Dav
s & Wilhour
(1976)
Fir, White
Resistant
Davis & Wilhour
(1976)
Pine, Limber
Resistant
USDA (1973)
Pine, Mugs
Resistant
Davis & Wilhour
(1976)
Pine, Pinton
Resistant
Davis & Wilhour
(1976)
Fir, Subalpine
Sensitive
Davis & Wilhour
(1976)
Pine, Short Leaf
Intermediate
Treshow (1970)
Sagebrush, Big
Intermediate
Davis & Wilhour
(1976)
Source: Dvorak, 1978
331
Table 5.2-3
Percent of the Total Leaf Area Injured by Different Concentrations
of SO2 in Two-Hour Field Fumigation Studies
Average percent injury
Number of replications
Species
SO;
.5
ppm
1
ppm
2
ppm
4
ppm
6
ppm
10
ppm
0
0
0
0
22
0
10
60
0
0
0
16
38
0
0
10
15
0
0
0
20
78
0
0
0
1
1
0
0.2
3
0
22
0
0
33
80
0
0
21
0
4
9
2
0
0
1
5
2
0
30
0
0
50
50
0
0
0
0
0
0
0
0
0
0
13
96
0.6
0
0
5
0
0.4
10
25
0
2
5
7
0
1
40
0
0
0
5
»
0
6
0
0
14
0.2
0
3
0
15
80
0
0.4
8
0
16
40
0
0
0
0
0
0
43
2
0
19
95
.5124 6 10
ppm ppm ppm ppm ppm ppm
Abies concolor
(White fir)
Abies lasiocarpa
(Alpine fir)
Acer glabrum
(Rocky Mountain maple)
Achillea millefolium
(Yarrow)
Agoseris glauca
(Mountain dandelion)
Agropyron caninum
(Wheatgrass)
Agropyron desertorum
(Crested wheatgrass)
Ambrosia sp.
(Ragweed)
Amelanchier utahensis
(Utah serviceberry)
Antennana sp.
(Pussytoes)
Arabis pulchra
(Rockcress)
Artemisia ludoviciana
(Louisiana sage)
Artemisia tridentata
(Big sagebrush)
Aster chilensis
(aster)
Astragalus utahensis
(Locoweed)
Atriplex canescens
(Fourwing saltbush)
Atriplex confertifolia
(Shadscale)
Betula occidentals
(River birch)
Bouteloua barbata
(Six-weeks grama grass)
Bouteloua gracilis
(Elue grama grass)
Bromus ciliatus
(Fringed brome)
Bromus inermis
(Smooth brome)
Bromus tectorum
(Cheatgrass)
Cercocarpus ledifolius
(Curl-leaf mountain mahogany)
Cercocarpus montanus
(Mountain mahogany)
Chenopcaium fremontn
(Goosefoot)
Chrysothamnus nauseosus
(Big rubber rabbitbrush)
Chrysothamnus stenophyllus
(Little-leaf rabbitbrush)
Chrysothamnus viscidiflorus
(Sticky-flower rabbitbrush)
Cirsium undulatum
(Thistle)
Clematis ligusticifolia
(Western virgin's bower)
Cleome sp.
(Beeplant)
Cowama mexicana
(Cliffrose)
Cryptantha humilis
(Catseye)
Cynoglossum officinalis
(Houndstongue)
Descurainia californica
(Tansy mustard)
Ephedra viriais (Mormon tea)
Equisetum sp. (Horsetail)
EriC/gCnum tacemosum
(Buckwheat)
Euphoroia serp/lhfoha
(Spurge)
Eurotia lanata (Wmterfat)
Geranium ricnardsonn
(Vvhite geranium)
Gilia sggregata (Scarlet f Hia)
12
6
7
15
0
86
14
1
1 1
3 2
1 1
3 2
2 3
2
5
3
1
1
4
1
1
1
15
1
2
2
2
10
2
2
9
1
2
1
1
3
1
5
1
1
1
1
2
7
1
4
1
1
3
Table 5.2-3 (cont.)
Average percent m|ury Number of replications
SO:
.5 1 2 4 6 10 .5 1 2 4 6 10
Species ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm
ppm
0
100
0
0
40
75
0
0
0
0
0
0
28
0
0
25
2
1
1
1
2
5
1
9
1
1
2
1
4
1
1
1
2
2
7
9
3
1
1
14
17
1
Gutierrezia sarothrae 0 0 21 78 4 2 13
(Snakeweed)
Hackelia floribunda 0 0 11
(Stickseed)
Haplopappus nuttalln
(Goldenweed)
Hedysarum boreale
(Sweet vetch)
Hjlaria jamesii 0
(Galleta)
Hymenoxys richardsonii
(Hymenoxys)
Juniperus osteosperma
(Utah juniper)
Juniperus scopulorum 0 0 0 25 1
(Rocky Mountain juniper)
Lepidium sp. 0 1
(Peppergrass)
Machaerantbera canescens 25
(Spiny-leafed aster)
Mahonia repens 0 0 0 1
(Oregon grape)
Malacothnx sonchoiaes 0
(Desert dandelion)
Munroa squamosa 0 0 0 0 3 2
(False buffalograss)
Oenothera sp. 6 12 5 3 3 1
(Evening primrose)
Opuntia sp. 0
(Prickly pear cactus)
Oryzopsis hymenoides 0.2 2 2 17 29 90 4 9 8
(Indian ricegrass)
Oryzopsis micrantha 4
(Ricegrass)
Pachystima myrsinites 0 1
(Mountain lover)
Penstemon sp. 15 70 1
(Penstemon)
Phacelia corrugata 0 2
(Scorpion weed)
Picea pungens 0 0 0 12 3
(Blue spruce)
Pmusedulis 0 0.06 2 4 9
(Pinyon pine)
Pinus ponderosa 0 0 1 2 3
(Ponderosa pine)
Poa pratensis 0 0 7 15 3
(Kentucky blue grass)
Populus angustifolia 002 11 20 36252
(Narrowleaf cottonwood)
Populus tremuloides 0 0 012 7 0 123 11 8
(Quaking aspen)
Pseudotsuga taxifolia 0 0.8 5 4
(Douglas fir)
Quercus gambelii 0 8 1
(Gambel oak)
Rhus trilobata 0.3 0 1
(Squawbush)
Rosa woodsii 0 1 15 90 60 6 3 5 2
(Wild rose)
Salsola kali 7 3 3 2
(Pussian thistle)
Senecio streptanthifolius 0 8 3 1
(Groundsel)
Silene menziesii (Catchfly) 0 1
Sitanion hystrix 0 1
(Squirreltail)
Sphaeralcea sp. 0 0.03 17 40 2 4 3
(Cutleaf globe mallow)
Sphaeralcea parvifolia 20 22 43 38 30 2 7 3 7 2
(Globe mallow)
Sporobolus cryptandrus 000 0 0 3287
(Sand dropseed)
Stipa occidentalis 0 73 4
(Needlegrass)
Symphoncarpos oreophilus 0.3 6 18 32 4 4 6 3
(Snowberry)
Tragopoeon dub'us 0 4 8 2 2 3
(GoatSLearc')
Tnsetum spicatum (Tnsetum) 90
Viola sp. (Viola) 25 2
Yucca sp (Yucca) 0
Zygadenus paniculatus 0 0 13 1 1 2
(Deatn camas)
333
too dilute to cause any effects. The most resistant species
(Douglas Fir, Pinon Pine, and Arizona Ponderosa) all grow in
higher elevations and the three most sensitive species, (Good-
ding's Willow, Cocklebury, and Sunflower), all grow in low, wet
areas. Humidity plays a role in determining the threshhold value
for SOp injury. Higher humidities tend to lower the SO- levels
needed to create a response. Generally, injury was proportional
to new growth and smaller, less developed individuals were more
sensitive. Symptoms were visible within one and one-half days
after fumigation. High temperature and wind increased symptom
maturation (Caldwell, 1976).
Plants, in general,
SOp injury; however, animals
in habitat or food species,
occur. Sulfur is known to
protein synthesis. Enzymes
catalase are particularly sensitive,
increased airway resistance, decreased
are more sensitive than animals to
are impacted indirectly by changes
Direct effects in animals also
inactivate enzymes, thus altering
such as diastase, peroxidase and
In man, the effects may be
mucus flow rate, increased
susceptibility to respiratory infection and chronic respiratory
disease. Six to ten exposures of 0.2 ppm for 10 seconds each has
produced altered e 1 ect r o- e nee pha 1 o grams . Recent population
studies indicate that, at lower concentrations, inhaled sulfuric
acid and specific sulfates produce even greater irritability than
from S09 (Coffin and Knel son 1976).
Studies by Colucci (1976)
pulmonary function in laboratory
6.75 ppm for two to three hours,
with chronic concentrations of
Epidemiological studies indicate
ppm can adversely affect human
animals with higher ventilation
tissue per body size would be
Results of Colucci 's studies may
show deleterious effects to
animals with acute exposures of
Pulmonary dysfunction occurred
4.86 ppm for several months.
that chronic exposures of 0.04
populations. It follows that
rates or more exposed mucosal
more sensitive (Dvorak, 1976).
be reviewed in Table 5.2-4.
Another integral part of SO^ emissions concerns the
combination of S02 and nitric oxide as acid precipitation. The
acidification of many freshwater lakes and streams has become an
area of extreme concern in Northern Europe and Northeastern North
America. The acidity of precipitation has been on the rise in
this area since the early 190 0's because of increased emissions
of acid-forming sulfur and nitrogen compounds. This acidic
precipitation can lower the pH of soils and natural waters caus-
ing mineral leaching and damage to many aspects of the biosphere.
Studies by Hendrey, et . al . (1976) show that the acidi-
fication of freshwaters produces many changes in the aquatic
environment. In six Swedish lakes, where pH had decreased by 1.4
to 1.7 units during a forty-year period, bacterial activity had
apparently decreased, leaving dense amounts of fungal hyphai on
sediment surfaces. Decreased pH was believed to be the cause for
the shift in dominance of organisms from bacteria to fungi, with
the consequent decrease in oxygen consumption and interference
with nutrient recycling by microdecomposers (Hendry, 1976).
334
Table 5.2-4
Summary of Toxicological Experiments with Sulfur Dioxide ( SOp )'
Concentration
S~ecies
(10- _c
Duration
Effects
'•'on key
<0.034
78 weeks
None
• ey
<0.078
.7
None
Impaired bronchial clearance
Dog
0.13
21 hours/day for 620 days
None
-
0.13
78 weeks
None
Guinea |
<0.13
22 hours/day for 365 days
None
Dog
0.13
21 hours/day for 225 days
Increased pulmonary resistance
:;:
0
.026-0.079
12 hours/day for 4 months
None
Mouse
c
.18 -0.26
7 days
Increased sensitivity to pneumonia
infection
: : : :
0.26
3-10 days
Increased S-sulfonate clearance
Mouse
Up to 72 hers
Lesions in respiratory tract
'■ 3t
6 hours/day, 5 days/week
for 11 3 days
None
- c
6 hours/day, 5 days/week,
for 22 days
40r mortality
6 hours/day, 5 days/week,
for 12 days
--90 mortality
• == pig
6 hours/day. for 2C days
None
'
0.52
Increase in pulmonary flow
resistance
- DO i X
14 and 62 hours
Formation of S-sulfcnate
": .se
13
5 min/day, 5 days/week
for 300 days
Accelerated onset of neoplasia
-=~ster
14
3 hours/day for 75 days
Increased pulmonary infection
13-14
2 hours/2 tines/week for
4 to 5 months
Change in goblet cells of bronchi
and bronchioles
13-78
Change in goblet cell release
Rat
26
Up to 6 weeks
None
52
Up to 6 weeks
Bronchial damage
104
Up to 6 weeks
Death within 22 days
-
78
6 hours/day for 10 days
Increased acid phosphatase activity
-
78
2 hours
Gastric inhibition
.se
:7£
10 exposures of 10 min-
utes, with 3 or 7 min-
utes recovery between
exposures
Initial decrease in respiratory
rate, then progressive return to
preexposure rate; desensi tization
to successive exposures.
Mouse
Various
Sensitized mice to pneumonia
infection
Data extracted ir" sumnary of Colluci (1976) and presented in order of increasing concentra-
tion, except ^rere there is more than one entry for a single experiment.
Source: Dvorak, 1973
335
The interference with microdecom poser activities impacts
on invertabrates, as food availability and variety is decreased
(Hendrey, 1976). Devastating effects have been seen in fish
species. In Norway, huge amounts of adult salmon and trout have
been killed in connection with spring snow melt or heavy autumn
rains. Sweden has reported the extinction of the salmonid popu-
lation, and severe effects in the roach, perch, and pike communi-
ties. Metal smelters in Sudbury, Canada, which emit 2.64 million
tons of SOp annually, have been thought to be the cause of the
rapid disappearance of lake trout, lake herring, white suckers,
and other species in the La Coche mountain region during the
1960's. PH values as low as 4.5 were not uncommon in this re-
gion. In the Adirondack Mountains of New York State, intensive
studies revealed pH levels less than five to be present in 51% of
the higher elevation lakes, and 90% of these lakes were devoid of
fish life. Species such as brook trout, lake trout, white suck-
er, brown bullhead and several cyprinid species were completely
eliminated over a period of forty years. Cause of death at pH
be the result of a coagulation of
subsequent anoxia. At pH levels of
be a disturbance of the normal ion
appears that small fish are more
the same species. Smaller fish
per unit weight, which hastens
levels less than three may
mucous on gill surfaces and
four to five,
and acid-base
sensitive than
have a 1 arger
the cause may
bal ance . It
1 arger members of
gill surface area
ion fluxes. Age-specific mortality has not been clearly defined
although there are indications that age may play a role in some
species (Schofield, 1976).
precipitation on soils may be bene-
Because it increases the amounts of
benefit may outweigh any
of valuable soil miner-
other cations, has been
as soil structure, tex-
so widely, it is diffi-
that increased acid will
The effect of acid
ficial as well as harmful,
sulfur and nitrogen, the added nutrient
deleterious effects. However, leaching
als, such as Calcium and Manganese, and
linked to acid precipitation. Inasmuch
ture, and cation exchange capacity vary
cult to determine completely the effect
create without first classifying the soil type. Susceptibility,
as discussed by Maimer (1976), varies as follows. Natural soils
with high pH and base saturation are usually highly resistant,
along with soils rich in clay and organic colloids. On the other
hand, acid and sandy soils and soil types that are transitional
between brown earths and podsals will be more seriously affected
by increased acidity. It is relevant also to bear in mind that
acid precipitation may carry many other pollutants to the soil,
which may increase or counteract expected effects (Maimer, 1976).
As soils are affected, biological effects will be seen
on forest vegetation. Some species of lichens, which have the
capacity to fix molecular nitrogen from the air, are quite sensi-
tive to S0~ and lose their nitrogen-fixing ability when subjected
to acid precipitation. However, this may not be harmful to
forest trees as they are not obligate nitrate plants. The addi-
tion of acid rain is also expected to cause the release of alumi-
num and heavy metal ions from the soil, which are toxic to many
336
plants. It is also felt that nitrogen is accumulating in forest
soil, and this accumulated nitrogen is expected to be transformed
to nitrate and leached after clearfelling or forest fires. The
results of this net acidification during a short period of time
is not clearly known. However, it is expected that this condi-
tion will contribute to a decreased growth rate of trees (Tamm,
1976). Although effects of acid precipitation have not been
established in California, it is being monitored presently in the
Ukiah District in order to evaluate trends for future considera-
tion.
Nitrogen Oxides
n i t r
tota
atmo
fert
cal
t i on
bact
sour
Di st
with
and
(12,
Like SCU, coal-fired power plants are a major source of
ogen oxides. These plants are responsible for 11% of the
1 nitrogen oxide emissions in the U.S. Other sources of
spheric nitrogen include ammonia (NH.) from biodecay and
ilizers, nitrogen oxides (chiefly NO and N02) from biochemi-
reactions within the soil, and also h ig h- t emperat ure combus-
processes. Taken on a global scale, most NO is produced by
eria, about 50 x 10 tons per year as compared to man-made
ces which account for 5 x 10 tons per year. In the Ukiah
rict, typical emissions densities for oxides of nitrogen are
in the range of 5,000 to 12,000 tons per year (TPY). Sonoma
Solano Counties exhibits the highest level of NO emissions
000-18,000 TPY).
Soils and plant life have not shown any detrimental
effects of increased atmospheric nitrates at their present level
(Noggle, et . al . , 1978). In fact, atmospheric nitrate is bene-
ficial because it restores the small quantities of nitrates lost
in a mature ecosystem.
Animals and man, however, can be adversely affected by
nitrous oxides as they are quite destructive to lung tissue. NO^
is relatively insoluble in water and therefore is not scrubbed by
tracheal and bronchial linings. This results in greater penetra-
tion into the lungs, interference with bacterial activity of
macrophages, increased susceptibility to infection, bronchial
inflammation, and loss of cilia. Long-term, low-level doses may
result in an emphysema- type injury, decreased pulmonary compli-
ance, and increased lung weight (Kavet and Brown).
Predicted worst-case NO emissions from a 2100 MWe
generating station within about a one-half mile radius exceed 5.3
ppm for a short time period. Table 5.2-5 gives an indication of
the adverse effects possible even at this level. Epidemiological
studies indicate that humans may be adversely affected by chronic
exposures to 0.53 of NO
2*
The effectiveness of extrapolating
these data to wildlife in the region is uncertain (Dvorak, 1978).
It is known that N0o in combination
severe effects at levels where S0~ or N0~
a visible response. Since coal combustion
counts for approximately 40% of total
with S0o can produce
alone would not produce
i n power pi ants ac-
sulfur compound emissions
337
Table 5.2-5
Summary of Toxicological Experiments with Nitrogen Oxides (NO V
A
Species
Concentration
(105 ug/m3)
Duration
Effects
Acute exposures
Guinea pig
0.01-0
20
4 to 24 hours/day for
up to 14 days
Elevated protein in urine
Guinea pig
0.04
Up to 21 days
Increased average area per alveolar
wall cell
Mouse
0.02-0
30
Up to 17 hours
Impaired bacterial defense
Monkey
0.2 -1.
0
2 hours
Decreased tidal volume, progressive
histopathclcgical damage
Rat
0.30-0.
34
48 hours
Increase in Type II pneumocytes
Rabbit
0.16-1.
2
3 hours
Impaired bacterial defense at all
levels of exposure
Hamster
0.60-0.
70
7 to 10 days
Chronic exposures
Bronchiol itic lesions
Mouse
0.01
Up to 12 months
Reduction of functional lung tissue
Monkey
0.02
493 days
Slight to moderate emphysema
Monkey
0.04
14 months
Hypertrophy of bronchiolar epithe-
1 iur, in bronchiole
Rat
0.02
14 months
Marginal changes in epithelium
Guinea pig
0.02
6 months
Higher mortal ity
Rat
-.0.06
9 months
Decrease in lung compliance
Rat
0.04
Li fetime
"Emphysema-like" injury suggested
Rat
0.04
0.34
Up to 360 days
Up to 7 days
Increase in number of cells prepar-
ing to divide
Rat
0.12
6 weeks
Interstitial edema, vascular
congestion
Rat
0.20
90 days
Decreased body size
Rat
0.30
90 days
Decreased body size
Mouse
--0.80
Up to 8 weeks
Epithelial damage near terminal
bronchioles
Hamster
0.9-1 .1
10 weeks
Respiratory rate increased, hyper-
plasia and hypertrophy in termi-
nal and respiratory bronchioles
'Data extracted from summary of Ziskind and Hausknecht (1976) and presented in order of
increasing concentration, except where there is more than one entry for a single experiment.
Source: Dvorak, 1978
338
and about 11% of total nitrogen oxide emissions in the continen-
tal U.S., it is important to look to these immediate areas for
pollutant responses.
Carbon Monoxide
Within the Ukiah District, BLM lands in Yola, Napa,
Marin and southern parts Solano and Sonoma Counties are in non-
attainment areas. Other BLM lands are situated in areas that are
unclassified or better than national standards as shown in Figure
5.3-4.
The toxic properties of carbon monoxide have been known
to man for quite some time. Unfortunately, studies involving
environmental aspects such as soils, wildlife, vegetation and
archaelogy have not been published to the same extent as many
other air pollutants. For this reason, carbon monoxide effects
on man and mammals alone will be discussed.
Ninety-five percent of carbon monoxide emissions may be
attributed to automobile exhaust and, because they are released
near the ground, these emissions do not undergo substantial
diffusion. This fact coupled with CO's lack of involvment in
further atmospheric reactions to form secondary pollutants,
accounts for the very high levels in urban areas. The situation
is complicated further in that CO measurements in urban areas may
be critically underestimated. Studies were conducted by Cortese
and Spengler (1976) in the Boston area to determine the ability
to represent carbon monoxide exposure by fixed monitoring sta-
tions. In this experiment, 66 non-smoking individuals carried
portable CO samplers at breathing levels for the period October
1974 through February 1975. Results showed that four of the 66
volunteers, who commuted to work daily, were exposed to 37 ppm CO
because of faulty automobile exhaust systems. This level is in
excess of the National Ambient Air Quality Standard for one-hour
35 ppm. Considering the other volunteers, concentration of 5 to
20 ppm occurred 85% of the time, 5% were greater than 23 ppm and
1% were over 31 ppm. Comparison of these levels to fixed loca-
tion monitors in the area, show that the mean one-hour personal
exposure concentration (25.3 ppm) was 1.6 times greater than the
fixed monitoring concentration (15.6 ppm) for all area stations.
This difference may be due to the fact that CO concentrations at
breathing level may diminish by 5 to 15% by the time they reach
the usual monitoring height of 15 feet (Cortese, et
This study would indicate that CO concentrations, as
may actually be significantly higher in urban areas or
travel ed roadways .
al, 1976).
moni tored ,
on heav i 1 y
Effects on small mammals may be derived through studies
by Mordelet-Dambrine (1978) and Finelli, et. al. (1976).
Mordelet-Dambrini ventilated guinea pigs and rats with 2.84% CO.
After two minutes, tracheal pressure variations were seen and
blood pressure and heart rate decreased within one to two min-
utes, respectively. Rats appeared to be more sensitive than
339
guinea pigs to CO inhalation. It was postulated that their
higher heart rate could trigger the higher sensitivity level
(Mordelet-Dambrini , 1978).
Finelli, et. al . (1976) studied the effects of clean
air, exhaust emissions with a catalytic converter, and carbon
monoxide emissions on 20 male rats for ^a period of four weeks.
CO levels of 57.5, 172.5 and 517.7 mg/m were used. During the
exposure period, 18 animals were killed, and there was a. dramatic
loss in heart, spleen and body weight. A trend of lower serum
cholesterol levels was significant in the rats exposed to the
highest CO levels. These effects were not seen in the group
exposed to the exhaust equipped with the catalytic converter as
CO amounts had been greatly reduced (Finelli, 1976).
Parallel studies have shown that adult rats exposed to
automobile exhaust without catalytic converters may also exhibit
elevated hematocrit and hemoglobin, cardiac hypertrophy, loss in
body weight and increased levels of serum lactate dehydrogenase.
Low levels have also caused increased serum and aortic cholester-
ol in rabbits. This may be a factor in the development of arter-
iosclerosis in humans (Finelli, 1976). Also in humans, it is
known to affect the heart, brain and muscle tissue most seriously
because CO has a high affinity for hemoglobin and thus limits the
amount of oxygen available to all body tissues, these three being
extremely sensitive to oxygen deficiencies. CO has also been
associated with reduced ability to perform vigilance tasks and
reduced exercise tolerance (Cortese, 1976).
Any of these symptoms may also be seen in species native
to the Ukiah District. Possibly, symptoms may be more severe in
animals with higher heart rates and more lung tissue relative to
body weight. However, care should be taken in extrapolation of
data .
Hydrocarbons
Hydrocarbon emissions are below 25,000 tons per year in
all areas of the Ukiah District with the exception of Sonoma
County where emissions reach 26,000 tons per year. As in the
case for carbon monoxide, studies involving hydrocarbons as an
air pollutant are not as numerous as those concerning many other
ai r pol 1 ut ants .
There are three basic sources of hydrocarbons: animal,
mineral and vegetable, such as municipally operated sewage treat-
ment systems, industrial
and decaying vegetation,
leum hydrocarbons escape
marine facilities and
(Boyd, 1976).
discharges from oil-dependent industries
Over 90% of major discharges of petro-
from pipelines, tank ships, tank barges,
onshore production storage facilities
340
At the 1977 American Petroleum Oil Spill Conference, it
was reported that in California, concentrations of petroleum
hydrocarbons were found in almost all benthic and sandy interti-
dal sediment samples collected in the Southern California border-
land (Reed, 1977). As hydrocarbons collect in soils and water,
an effect will be seen on algae and photopl ankt on . Retardation
of algae growth and inhibition of photosynthesis has been linked
to the presence of petroleum hydrocarbons. A reported growth
stimulation in photopl ankt on may be due to the slight carcino-
genic stimulatory activity of low HC levels (Vandermuelen, 1976).
Effects of hydrocarbons on fish have been well docu-
mented by Adams (1975). Studies indicate that recreational
vehicles, such as snowmobiles and motor boats, add dangerously
high amounts of hydrocarbons to lakes. Death of fish may occur
at levels of a few ppm and feeding, homing and reproduction are
disrupted at levels of 10 to 100 ppb. These exhaust hydrocarbons
concentrate in fatty tissue such as lateral line muscle and
visceral fat. These compounds remain in the tissues and are
passed to higher animals through the food chain (Adams, 1975).
Further discussion of hydrocarbon effects on fish will be inclu-
ded in a subsequent section, as this experiment also involved
1 ead val ues .
Ozone
Hydrocarbons and nitric oxides in the presence of sun-
light are known to produce ozone. Automobile exhaust, therefore,
may be considered as a primary source of the precursors which
give rise to oxidant. High ozone levels have been found not only
in the urban environment but also in rural areas, on mountain
tops, and at night. The reason for this ozone build-up is not
fully known; however, it is believed that ozone or its precursors
are being transported long distances or there may be a natural
source of hydrocarbons and nitric oxides within forests and
swamps, such as terpenes and methane. Within the Ukiah District,
areas in the southeastern section of the District have been in
violation of the federal one-hour standard for oxidant levels as
seen in Figure 5.3-11; however, these violations are on the order
of less than one percent of all observations per year.
Ozone is known to reduce photosynthesis in plants,
thereby reducing the nutrient value of the plant. Studies of air
pollution damage to the forests of the Sierra Nevada Mountains by
Williams et al (1974), indicated widespread oxidant-caused injury
to conifers. Especially susceptible were the ponderosa and
Jeffery pine as measured by the extent and intensity of chloratic
mottle on current year needles. Since ozone is dose- ace umul at i ve
for a variety of sensitive plants, a concentration of 0.06 ppm
over a five-month growing season would produce chlorotic mottle
on current year needles of the ponderosa pine. It should be
noted that this quoted level is within the federal standard of
0.12 ppm (Williams, 1977).
341
Results of the 1974 Sierra Nevada field survey showed
ozone injury to be most abundant in the mixed conifer forest
types located from 6000-8000 ft. in elevation. However, injuries
at mid-elevation, (4000-6000 feet), where many BLM lands are
located, tended to be more severe. These studies indicate that
ozone injury is dependent on elevation. At mid elevations, where
inversion levels are often found, injuries will be most severe.
At higher levels, where ozone is quite abundant, injuries are
more prevalent (Williams, 1977). Injuries to other species are
detailed in Table 5.2-6.
The California Department of Agriculture yearly assesses
damage to vegetation as caused by air pollution. In their 1970
summary, Millecan (1971) details the history of ozone damage to
California forests. In the early 1950's in the San Bernardino
National Forest, several pines began to turn chloratic and drop
needles. Ponderosa and Jeffery pine were particularly involved.
In 1963, it was first suggested that ozone might be the cause.
Later, in 1969, aerial surveys by the Forest Service and Uni-
versity of California at Riverside revealed the extent of ozone
damage. More than 161,000 acres of the ponderosa and Jeffery
pines in the San Bernardino National Forest, an estimated two-
thirds of the trees, were damaged by ozone. Of these, 3% were
dead, another 15% were severely affected, and 82% were moderately
or lightly affected (Millecan, 1971). Damage estimates have also
been assessed by the Statewide Air Pollution Research Center of
the University of California. Figure 5.2-1 reveals the extent of
oxidant injury as seen in 1974. Elevations over 8000 feet were
not considered in this study.
The Forest Service has been assessing ozone injury since
1974. A recent survey by Pronos et al (1978) revealed the extent
of ozone injury in the Sierra and Sequoia National Forests as
depicted in Figure 5.2-2. The worst injuries found were consid-
ered to be moderate and these were generally found at elevations
of 4000 to 7000 feet on the Front Range mountains west of the San
Joaquin Valley and along major river drainages. However, a quick
comparison of this data to photochemical levels found in the San
Bernardino National Forest show that the ozone levels of the
southern Sierra do not even approach the levels found in Southern
California forests as shown in Table 5.2-7 (Pronos, 1978).
Presently, no evidence of ozone injury has been seen or docu-
mented in the forests of the Ukiah District, but it is valuable
for the BLM Manager to be aware of the potential.
Impacts of ozone on man, animals and other air quality
related values have not been studied to the same extent as with
vegetation. However, ozone has been found to attack the cell
membrane, breaking double bonds and removing hydrogen atoms. In
humans, this process acts as a bronchoconst ri ctor , whereby less
air reaches the lungs. There is increased coughing and breath-
lessness, and lung elasticity is decreased. Also, there is
damage to alveolar macrophages in the presence of high concentra-
tions of ozone, increasing the susceptibility to infection and
342
Table 5.2-6
Site Characteristics and Extent of Ozone Injury
1
Elevation
Si
>eues w it!i
Local in
(meters)
lopog
rapra
Site
s
\. niptonis
Land use
Delilah 1 0
15 64
Ridge
Flat,
Ponderosu (PPj
National Forest
Dry
(N F)
Mt. Sam;i>on
1623
Ridge
Steep
Dry
PP
BL-.
ck Oak (BO j
NF, Private
McKensic Rid-e
1600
Ridge
Flat,
Dry
PP,
BO
NT
Converse Basin
157T
Basin
Mesic
PP.
Sugar Pine
NF
(SP)
Giant Sequoia
(GS)
Hume Luke
1577
Basin
Mesic
PP.
P
SP. Jeflery
ine(JP)
NF
Boy den Ca\r
970
Qjnvon
Bottom
Dr\,
Steep
PP
NT,
Nat ional Park
(NF)
Pi.-.-, k.jre
2199
Ridge
Steep,
PP.
JP.SP
Ro. :ky.
W'h
ite Fir (WT |
NP
Moist
Buck R^ck
25'^
Ridge
Steep.
Rockv
JP
Lo
igepole Pine'
NT
Weaver Lj.-.;
2oc9
Fiat
Dn
JP.
P
Lod'gepole
mt?
NF
■
1638
We : -
i>e
Moist
PP,
BO.W'F, SP,
L'niv. of Calif.
F jre^t
GS
- 1
'
West Sio
pe
Dry
PP.
BO. W F
NT , Private
. • .- S
lO^u
Fia:
Dry
PP.
BO
NF, County, Pri-
vate
Sierra I "«;enn
970
Flat
Dry
PP
Private. County ,
State
- ■
1517
Variable
Moist
PP.
BO
NF
: :m Point
1517
Rid,;t
Dry
PP,
BO
NT
Sk. eway Grove,
1517
Fiat
Moist,
JP
NT
Muir Crc\e
Rocky
Lod;;epe.e RS
2038
Flat
Moist,
Ro. k\
JP.
LP
NP
Crystal Cave
141-f
Flat
Mesic
PP.
BO, WT
NT
G.j:." Fc '- S!
191 i
Flat
Mesic
J P.
BO
NP
Co!on\ Mi!! RS
.
Ridee
Dry
PP.
WT, BO
NP
Moro Rov k
1SS0
South S
ope
Mesic
PP
NT
Cr !ow
1914
Meadow
Mesic
JP
NT
1 Milk Ranch Peak
1897
South J
ope
Drv
PP,
WF.SP,
NT
1
BO
j Mineral K
2254
Canvon
Bottom
Mesic
JP
NT
Source: Williams, 1977
343
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C
o
•r-
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L
-l->
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344
Figure 5.2-2
Location of Ozone Injury in the Sierra and Sequoia National Forests, 1977
Source: Pronos, 1978
345
Table 5.2-7
Comparison of Ozone Concentrations in the
San Bernardino National Forest (Sky Forest, 5640 feet)
With Concentrations in the Southern Sierra Nevada (Whitaker's Forest, 5400 feet)
June - September 1977
LOCATION
JUNE
JULY
AUGUST
SEPTMEBER
MAX.
HRLY.
AVER,
(pphm)
MEAN
of MAX.
HOURS
(pphm)
MAX.
HRLY.
AVER,
(pphm)
MEAN
of MAX.
HOURS
(pphm)
MAX.
HRLY.
AVER,
(pphm)
MEAN
of MAX.
HOURS
(pphm)
MAX.
HRLY.
AVER,
(pphm)
MEAN
of MAX.
HOURS
(pphm)
Sky Forest
32
20
30
22
33
19
24
14
Whitaker's
Forest
14
10
15
11
14
11
13
9
(Concentrations are expressed as maximum hourly averages and means of maximum hourly
averages, and are shown as parts per hundred million.)
346
cases of pulmonary edema. With wildlife, we can expect these
effects to be seen to an even greater degree, as injury in most
cases is more severe in animals with more respiratory tissue per
body wei ght .
Lead
3
The thirty-day standard for lead is 1.5 yg/m . Near the
city of San Rafael in Marin County, violations of this standard
may be expected 6 times per year. Environmental sources of lead
include the petroleum, paint and ceramic industries, and coal
combust i on .
Lead has become a serious environmental pollutant to the
agricultural industry and is a major concern in the vicinity of
major roads, as lead collects and accumulates in the soil. To
date, plants show no toxic effects, and lead absorbtion by plants
is insignificant. Concern, however, stems from the rise in lead
content of plants and in animal feed, for these accumulations
will affect the entire food chain (Keller, 1977)
As lead accumulates in the soil, long-term changes in
productivity, decomposition, nutrient cycling, and insect and
mycrobial activities may be seen. In the case of the Hubbard
Brook Experimental Forest in Central New Hampshire, lead is
accumulating at the rate of 0.67 pounds per half acre per year.
measured include precipitation, winter snow and
The soil and especially forest floor humus was
major sink for lead, while lead uptake in vege-
low. The entire system, however, is functioning
from the atmosphere and hydrologic systems and
soil system. With this current input rate, the
doubling time for lead concentration in forest humus would be
only 50 years and since lead deposits from the atmosphere have a
mean residence time of 5000 years, long-term concentration should
be carefully evaluated (Siccama, et. al., 1978).
Sources of lead
stream water,
found to be the
tat i on was quite
to remove lead
pi ace it in the
Effects of lead accumulations on fish have been studied
by several investigators. Hodsons, et al (1978) has shown that
lead uptake in rainbow trout is a function of the pH of the
water. Blood lead concentrations increased by a factor of 2.1 as
pH decreased by 1.0 unit. Consequently, lead sensitivity in-
creased with low pH levels. The author suggested that low pH
increases the permeability of the gills. Sublethal concentration
of lead for a period of three to six months may cause spinal
deformities. Lead is also known to cause behavioral changes in
fish at 70 ppb and death at 0.3 ppm. Therefore, pH should be
monitored in streams known to have high lead values (Hodson,
1978) .
Badsha and Sainsbury (1977) have studied first year
whitings in the Severn Estuary and feel that bi oaccumul at i ons are
functions of the food chain rather than respiration and gills.
Therefore, bottom feeders would be expected to accumulate rela-
tively higher lead amounts than other types of predators. Once
347
ingested, lead is not rejected and slowly increases (Badsha, et .
al., 1977). Effects on fresh water fish may be quite similar
according to experiments by Rehwoldt, et . al . (1978) in the fresh
water stretch of the Hudson River system. In this study several
species of fish were caught and lead levels were compared to
those of preserved samples. Results are given in Table 5.2-8 and
indicate that lead levels are time independent in a relatively
clean system such as the Mid-Hudson (Rehwoldt, 1978).
Studies by Adams (1975) involve the effects of lead and
hydrocarbons on brook trout. Increasing amounts of these two
pollutants are released to the aquatic environment by snowmobiles
and outboard motors each year and are attracting much attention.
Towle's Pond in Freeport, Maine, served as the site for several
experiments. Water samples in November 1971 showed 4.1 ppb lead
and no detectable hydrocarbons as a baseline concentration.
Through the winter seasons of 1971 and 1972, 56.8 liters of
gasoline were burned in snowmobiles operating on the pond.
During ice-out, lead levels increased to 88 ppb in 1972 and 135
ppb in 1973. These lead levels decreased rapidly within 72 hours
of ice-out and returned to near normal within six days. Lead
levels in exposed fish were 15.7 and 8.8 times those of control
fish in 1972 and 1973, respectively. Four fish died during the
first six hours of the 1973 experiment. Cause of death has been
attributed to low oxygen levels in the pond during that period.
Hydrocarbon levels ranged from 1 to 10 ppm and an oil slick was
visible on the pond for one week after ice-out each year. Levels
in exposed fish ranged from 0.1 to 1 ppm. Laboratory study
revealed highest lead levels occur in the digestive tract (3.3
times that in control groups) and lowest in the gills, which may
further indicate that bottom predators may be seriously affected
by increasing lead levels. Elevated lead levels were also found
in muscle skin and gills (Adams, 1975).
soil ,
lead
vege-
coul d
5.2-9
The pathological effects of lead in small mammals are
detailed in reports by Roberts, et . al . (1978). Two abandoned
metaliferous mines in Wales were chosen as the sites for
vegetation and mammal tissue measurements to determine
accumulations. The area was typified by sparse natural
tation, with a limited range of species, as few populations
survive the heavy metal concentrations in the soil. Table
indicates the lead amounts found in the soil, vegetation and
invertebrate populations. Small mammals were caught in the area
and examined for lead content. Vegetarian feeders were found to
have the highest level concentrations and insectivorous mammals
the least. In these mammals, bone and kidney tissues had the
highest lead concentration, and the liver, brain, and muscle
tissues had the least. This supports the generally accepted idea
that the skeleton is the main long-term storage site for lead
(Roberts, 1978).
Mice were fed lead acetate at levels of 0.1% and 4.0% in
experiments by Eyden , et . al . (1978), to determine toxicity. The
animals suffered weight reductions, increased sperm abnormal ti es ,
348
Table 5.2-8
Average Values (m/g) for Lead in Dry Weight
Common Name
Source
Pb
Alewife
MC 10 (1976)
VC 2 (1953)
0.30
0.61
Atlantic Sturgeon
MC (1976)
NYS 5 (1924)
0.82
0.71
Fundulus
MC 21 (1976)
VC 4 (1953)
NYS 3 (1936)
AMNH (2) (1973)
0.51
0.62
0.41
1.10
Small Mouth Bass
MC 11 (1976)
NYS 3 (1936)
1.06
0.99
Spottail Shiner
MC 17 (1936)
VC 5 (1953)
AMNH 2 (1973
0.59
0.69
0.77
Striped Bass
MC 14 (1976)
NYS 2 (1936)
AMNH 5 (1973)
0.92
0.40
0.21
Sunfish
MC 23 (1976)
0.25
White Perch
MC 26 (1976)
VC 2 (1953)
NYS 1 (1936)
1.06
1.02
0.80
* MC Marist College
VC Vassar College
NYS New York State Museum and Science Service
AMNH American Museum of Natural History
Number after source is sample size
Number in paranthesis is year caught
Source: Rehwoldt, et.al., (1978)
349
Table 5.2-9
LEAD CONCENTRATIONS (yg/g dry weight) IN SOIL, VEGETATION
AND INVERTEBRATES (mean + standard error, number of
samples in brackets)
Mine A
Vegetation
Lead
Invertebrates
Lead
Surface Soil
Lead
120 + 5.40(8)
61.9 + 14.5(6)
8430 + 2050(9)
Control
20.8 + 3.89(8)t
18.4 + 1.87(6)+
96.3 + 24.4(10)1-
Mine B
249 + 33.7(9)
81.7 + 18.6(5)
14010 + 6160(7)
Control
28.9 + 2.73(9)t
22.3 + 4.79(6)+
78.0 + 10.1(8)+
+ Denotes statistical significance at p < 0.001 (NS = p>0.05)
Source: Roberts, 1978
350
early hair loss, lethargy and reductions in mean survival time.
Symptoms were dose- dependent and the authors suggested that death
may be attributed to internal organ malfunction resulting from
enzyme interference, lack of nervous or hormonal infection from
depressed immunological competence (Eyden, 1978).
Lead is also known to accumulate in humans within the
blood, bones, urine, aorta, teeth, kidneys and liver. It has
been associated with anemia, arter i ocl erosi s , diseases of the
central nervous system, bone deterioration, kidney failure,
chromosome abberations, and brain damage. It is also known that
lead will pass through the placenta in pregnant women. Most
serious effects may be seen in young children, ages one to four,
as this is the time for normal development of the central nervous
system and bone tissue. Yankel et . al . (1977) observed blood
lead levels in young children living near a lead smelter in
northern Idaho and found amounts as high as 70 mg Pb/lOOml.
Ambient air, soil and dust lead levels were attributed to be the
major cause for the elevated lead levels. Air exposure alone
explained 55% of the variance (Yankel, 1977).
This section has detailed the effects of various pollu-
tants on air quality related values. Whenever possible, envir-
onmental concerns typical of the Ukiah District were stressed.
Where data was lacking, similar species or areas were described.
Relating these data to the Ukiah District may help to point out
critical areas for immediate study or future areas of concern.
Hydrogen Sulfide
The southern portions of the Ukiah District are located
within a natural geothermal area. Therefore, hydrogen sulfide
(H?S) is emitted to the atmosphere and most likely, these natural
emissions have caused violations of the California standard (0.03
ppm) for the past 50,000 years. Development of the geothermal
potential of this area, while decreasing natural emissions, has
at the same time increased man-made emissions.
1979 data from geothermal sources, as reported by the
State Energy Commission, show HoS controlled emissions to be 1600
tons per year and unabated emissions of 3100 tons per year.
Geothermal processes also release very low concentrations of
radon-222, mercury, arsenic, S0~, ammonia and boron. Presently,
all fifteen operating geothermal power units are located in
Northern Sonoma County; however, the potential for development
also exists in Lake, Mendocino, and Napa Counties. Violations of
the standard may be expected on the order of a few hours per
year. Studies in the Geyser s-Cal i stoga Geothermal Area have
noted unabated HUS maximum concentrations of 1.0 ppm and average
levels of 0.2 ppm during an 8-hour period. The worst known hUS
accumulation occurred at the Big Sulphur Creek watershed during a
nocturnal inversion and averaged 0.1-0.2 ppm. Fumigation studies
by Coyne and Bingham (1978) using H~S concentrations of 0.74 ppm
showed a ten percent increase in photosynt het i c rates for field
351
snap bean .
significant
fore , i t i s
not harmful
there is no
mal s , and
(Malloch, 1979).
Further studies by Shinn, et. al. (1976) also found a
increase in photosynthet i c rates for lettuce. There-
assumed that H~S levels found in the geysers area are
to vegetation types. According to Malloch (1979),
evidence
ambient
of HoS effects on water quality or on ani-
H ~ S revels are beneficial to vegetation
However, vegetation stress and damage has been noted
near the Geyser s-Cal i stoga Known Geothermal Resource Area (KGRA)
since 1973. Symptoms such as needle tip burn, leaf bronzing,
glazing, chlorosis, necrosis, reduced vigor and decreased lichen
abundance and diversity have been observed. Malloch, et . al .
(1979) have studied the vegetation injury in this area. High
concentrations of boron have been found in circulating water,
surface soils and leaf tissues and it is believed these harmful
effects may be attributed to boron toxicity rather than
(Malloch, 1979).
H2S
352
5.3
BASELINE AMBIENT AIR QUALITY
The Ukiah District encompasses portions of four air
basins as described in Section 4.8 - North Coastal, North Coastal
Mountains, San Francisco Bay Area and Sacramento Valley. Air
quality monitoring in the district is concentrated in major
cities for most of the pollutants, with an expanded network for
the monitoring of total suspended particulates (TSP). The exist-
ing monitoring network is shown in subsequent figures in conjunc-
tion with the pol 1 utant- speci f i c attainment status for each
county .
The California Air Resources Board (CARB), in accordance
with the requirements of the Clean Air Act Amendments of 1977,
has classified each county in terms of attainment of the National
Ambient Air Quality Standards (NAAQS). Air quality regulations
are discussed in considerable detail in Section 6; however, a
review of the attainment status of counties within the Ukiah
District provides an excellent means for defining baseline am-
bient air quality. Figures 5.3-1 through 5.3-4 show the current
status for each pollutant as designated for counties in the Ukiah
District. The figures illustrate which areas have been desig-
nated as non-attainment, cannot be classified, or better than
national standards for total suspended particulates and sulfur
dioxide. For oxidant, carbon monoxide, and nitrogen dioxide,
areas with sufficient data and poor air quality have been desig-
nated as non-attainment. Those areas with good air quality or
insufficient data have been categorized as "cannot be classified
or better than national standards." Since the unclassified areas
denote the lack of sufficient baseline air quality data, these
maps also indicate which counties require additional monitoring
stations to determine their status and thus their problem areas.
Baseline Levels
Ambient air quality values for 1977 for selected sta-
tions can be found in Appendix D while long-term baseline data
are presented in Appendix E. The values cover all of the major
pollutants, although every station does not measure all pollut-
ants of interest. The listings include the number of observa-
tions, the yearly high, the arithmetic and geometric means with
their standard deviations and the seasonal means and highs. The
frequency with which standards are equalled or exceeded is also
provided for each station.
Baseline ambient air quality data from Appendix D have
been summarized in Figures 5.3-5 and 5.3-6 for total suspended
particulates and sulfur dioxide, respectively. These parameters
have been selected for graphical presentation and detailed analy-
sis as they comprise the most readily available air quality data.
They also provide a good representation of the effects of both
industrial and agricultural (or outdoor) sources.
353
ELK VALLEY
ARCATA
7~3
[v
D
Does Not Meet Primary Standards
Does Not Meet Secondary Standards
Cannot Be Classified
Better Than National Standards
Figure 5.3-1
Ukiah District TSP Classifications
W.SACRAMENTO
354
ELK VALLEY
. SMITH RIVER A\
CRESCENT CITYV
\\\NV\v\\\\V^
NDEL NORTE
HOOPA ,Os
BLUE LAKE \\\
. . KORBELNN
v\\\\» KNEELAND
FORTUNA \\V0
SCOTIA « \A\\ . BRIDGEVILLE
ARCATA
Be
Un
tter Than Primary Standards
classified
W.SACRAMENTO
Figure 5.3-2
Ukiah District S02 and N02 Classifications
355
ELK VALLEY
ARCATA
. SMITH RIVER
CRESCENT CITY
DEL NORTE
KLAMATH
i
I
ORICK
HUMBOLDT
HOOPA .
BLUE LAKE
. . KORBEL
EUREKA
* KNEELANO
. FORTUNA
• . BRIDGEVILLE
1
Does Not Meet Primary Standards
Cannot Be Classified or Better Than
National Standards
W SACRAMENTO
Figure 5.3-3
Ukiah District CO Classifications
356
ELK VALLEY
ARCATA
. SMITH RIVER
CRESCENT CITY
lllllllllllll
DEL NORTE
llllllllllll
KLAMATH
ORICK
llllllll
HUMBOLDT
HOOPA .
miiim
BLUE LAKE | |
. KORBEL
EUREKA I I
KNEELAND
^
Unclassified
Primary Standard Violated
Figure 5.3-4
Ukiah District Ozone Classifications
W, SACRAMENTO
357
50
WOODLAND
W SACRAMENTO
RIO VISTA
SAN RAFAEL^
KENTFIELD
Figure 5.3-5
Annual Geometric Means ( yg/m )
For Total Suspended Particulates in the Ukiah District
NATIONAL AMBIENT AIR QUALITY STANDARD FOR TSP = 75 uG/M3 ANNUAL GEOMETRIC MEAN
CALIFORNIA TSP STANDARD = 60 yG/M3 ANNUAL GEOMETRIC MEAN
ARCATA
SO
2 Monitoring Stations
20
L_
20
40
_l_
60
-J
MILES
. CH -
• CALPELLA -• ^ # WILLIAMS
• ' •UPPERLAKE \
s v. \
V, «LAKEPORT > 1
\ • KELSEYVILLE . __ _-L
^~ 1 • DUNNIGAN
-- r ^ W S
• CLOVERDALE f S Vw*
• CLOVERDALE
\ J \
HEALDSBURG J"* \
\ DAVIS*
£ SANTA ROSA
• *SONOMA \« VACAVILLE
^ \ £ NAPA
NN • PETALUMA | * FAIRFIELD
Y / BEjfCIA
a WOODLAND
W.SACRAMENTO
RIO VISTA
SANRAFAE
KENTFIELD
Figure 5.3-6
Annual Average S02 Concentrations (pphm)
in the Ukiah District
NATIONAL AMBIENT AIR QUALITY STANDARD FOR S02 = 0.03 ppm
Source: CARB, 1977 359
Data are presented as contours of annual average values
for these pollutants based upon available data for monitoring
stations at locations as depicted in the figures. The reader is
cautioned in the use of these and subsequent figures that con-
tours have been provided based upon a limited amount of available
baseline air quality data. The analysis containing the figures
can be used with most confidence at locations near monitoring
stations. In more remote areas, additional monitoring data would
be required to confidently establish baseline levels. Such areas
include counties which have not been classified by the CARB under
the requirements of the Clean Air Act Amendments of 1977 due to
the absence of sufficient monitoring data.
Figure 5.3-5 presents annual geometric means for total
suspended particulates in the Ukiah District. The figure indi-
cates that particulate levels are lowest on an annual basis in
Lake, Napa, Sonoma and Marin Counties. In Lake County, values
are less 30 micrograms per cubic meter on an annual basis.
Highest total suspended particulate levels in the Ukiah District
are observed in Mendocino County and in the Sacramento Valley
portion of the District. Fort Bragg recorded the highest total
suspended particulate value on an annual basis in 1977 at 86.3
micrograms per cubic meter. This value is in excess of both the
California and Federal annual standards. In the Sacramento
Valley, values are in excess of the California annual standard as
well as the Federal secondary standard in eastern Colusa and Yolo
Counties. Higher particulate levels in this area are not unex-
pected due to the very high level of agricultural activity in
this region. The high particulate levels in the Fort Bragg area
are well correlated with observed heavy emissions of particu-
lates. Particulate levels in the extreme northwest decrease from
the elevated values observed in Mendocino County and are below
applicable standards for annual values of total suspended partic-
ul ates .
In summary, Figure 5.3-5 indicates that particulate
levels along coastal locations are lowest in the extreme southern
portion of the District increasing to a maximum at Fort Bragg.
Coastal values then again decrease with northward progression
through Humboldt and Del Norte Counties. In the inland valleys,
particulate levels reach minimums for the District and are quite
low on an annual basis. Progression further eastward into the
Sacramento Valley again reveals fairly high annual values of
total suspended particulates in excess of the California and
Federal secondary standards.
Annual average sulfur dioxide concentrations in the
Ukiah District are presented in Figure 5.3-6. Data are only
available for Vallejo, Benecia, Napa and Santa Rosa. For these
stations, only Benecia showed a non-zero annual average SCU
concentration. Sulfur dioxide levels tend to be low throughout
California and particularly in fairly rural areas such as the
bulk of the Ukiah District. No values in excess of the Federal
annual standard have been noted within the District.
360
The
levels in the
al variations
October while
January. It
due to mobile
tion of ozone
HC during which
1977 (CARB, 1977) data indicate that pollutant
Ukiah District are subject to fairly strong season-
Oxidant readings are highest between April and
carbon monoxide reaches peak levels from October to
should be noted that ozone formation is primarily
source emissions (autos, trucks, etc.)* The forma-
has a delay time from initial emissions of N0? and
and 0o
time these pollutants react with the sun
to form ozone
Sulfur dioxide, unlike ozone'
steady levels throughout the year. This
i n d i -
wh i 1 e
i n the atmosphere
rema ins at f a i rl y
cates that most S 0 ? is attributable to stationary sources
other pollutant levels are affected by seasonal changes in trans-
portation patterns as they are related to the combustion of
transportation fuels.
Frequency of Violations
Figures 5.3-7 through 5.3-10 provide the frequency of
violations of key standards for total suspended particulates,
carbon monoxide, oxidant and lead. A specific figure for sulfur
dioxide, nitrogen dioxide and sulfates has not been provided as
violations of these short-term standards were not were not re-
corded .
Figure 5.3-7 provides the frequency of violations of the
California twentyjfour hour standard for total suspended particu-
lates (100 ug/m ). The figure indicates that the short-term
standard is violated in all areas with the exception of the
extreme southeast which includes most of Sonoma, Napa and Marin
Counties. The highest frequency of violations occurred at Fort
Bragg where the short-term was violated nearly 40 percent of the
time. Along the coastal portions of the Ukiah District, the
frequency of violations ranges from zero in the extreme southeast
gradually increasing to nearly 40 percent at Fort Bragg, decreas-
ing again with northward progression into Humboldt and Del Norte
Counties where the frequency of violations drops off to 5 to 10
percent. The frequency of violations is also quite low in Napa
and Lake Counties which is in good agreement with the trend noted
on Figure 5.3-5 which presented the annual total suspended par-
ticulate levels throughout the region. The frequency of viola-
tions of the short-term standards increases with progression into
the Sacramento Valley portion of the Ukiah District. Eastern
Colusa, Yolo and Solona Counties show violations of the short-
term standard for total suspended particulates 10 to 20 percent
of the time. Violations in this area are largely due to agricul-
tural activity while the violations noted along the north coast
are due largely to natural sources and local fugitive dust emis-
sions. The high values observed in Mendocino County correlate
well with the high emission densities as described in Section
5.4.
The frequency of violations of the Federal eight-hour
standard for carbon monoxide is depicted in Figure 5.3-8 for the
Ukiah District. The figure shows a violation only at Vallejo, a
361
WOODLAND
W SACRAMENTO
san rafael!
^ 0
KENTFIELD
Figure 5.3-7
Frequency (%) of Violations of the California
24-Hour Standard (1) for Total Suspended Particulates
(1) CALIFORNIA 24-HOUR STANDARD FOR TOTAL SUSPENDED PARTICULATES = 100 uG/M'
Source: CARB, 1977 362
ARCATA
CO Monitoring Stations
20
_i_
MILES
40
_l_
60
-J
• DUNNIGAN
V,
DAVIS i
WOODLAND
W SACRAMENTO
• SONOMA X« VACAVILLE
NAPA
FAIRFIELD
RIO VISTA
SANRAFAEL*
KENTFIELD
Figure 5.3-8
Frequency (%) of Violations of the Federal 8-Hour
Standard (1) for Carbon Monoxide
(1) FEDERAL 8-HOUR STANDARD FOR CARBON MONOXIDE = 9 ppm
Source: CARB, 1977 363
ARCATA
W SACRAMENTO
KENTFIELD
0.1
Figure 5.3-9 sanrafael*
Frequency [%) of Violations of the
Federal 1-Hour Standard (1) for Oxidant
(1) FEDERAL 1-HOUR STANDARD FOR OZONE = 0.12 ppm*
* THE FREQUENCY OF VIOLATIONS WAS DETERMINED WITH RESPECT TO THE 0.08 ppm
STANDARD WHICH WAS IN EFFECT IN 1977. THE CARB DATA SHOWS FREQUENCIES WITH
RESPECT TO THE OLD STANDARD AND FREOUENCY OF VIOLATIONS WITH RESPECT TO THE
0.12 STANDARD CAN NOT BE DETERMINED FROM THESE DATA
Source: CARB, 1977
■shQ.
ARCATA
WOODLAND
W SACRAMENTO
Figure 5.3-10
Frequency of Violations of the
California 30-Day Standard (1) for Particulate Lead
(1) NUMBER OF MONTHLY AVERAGES > 1.5 UG/M3
Source: CARB, 1977
3fiB
metropolitan suburb of San Francisco. Carbon monoxide concen-
trations in more rural locations can be expected to be modest.
As indicated, elevated values for this pollutant are generally
due to large emissions associated with heavy vehicular usage.
The frequency of violations of the Federal one-hour
standard for oxidant is presented in Figure 5.3-9. Monitoring
stations for oxidant are presently only available in Yolo,
Solono, Napa, Sonoma and Marin Counties, the metropolitan suburbs
of the Bay Area. Data are largely unavailable for the bulk of
the remainder of the District; however oxidant levels in Mendo-
cino, Humboldt and Del Norte Counties are expected to be fairly
modest. The available data indicate that the one-hour Federal
standard is violated with the highest frequency in Yolo County at
approximately 1 percent of the annual period. The data show
increasing values of oxidant with eastward progression into the
Sacramento Valley portion of the District. Photochemical oxidant
emitted in the metropolitan Bay Area are transported into the San
Joaquin and Sacramento Valleys during the summer season resulting
in photochemical activity in this inland area. Along the coastal
portions of the District, the onshore transport of maritime air
generally results in ozone levels that are near or well below
background levels.
Finally, the frequency of violations of the California
thirty-day standard for lead is presented in Figure 5.3-10. Once
again, violations of the standard for lead occur most frequently
in heavy industrial or highly developed areas. This includes
Marin, Sonoma, Napa and Solana Counties. The frequency of viola-
tion reaches a maximum of over 6 percent of the annual period at
San Rafael. Available data for other areas of the District are
sparse and include Santa Rosa, Lakeport and Fort Bragg. At these
latter locations, the frequency of violations were zero and this
trend can be expected to continue in the northern portion of the
District.
Long-Term Trends
The data presented in Appendix E provide an indication
of pollutant trends in the Ukiah District. Oxidant data are only
available for select station within the District and only Fair-
field and San Rafael provide data for a significant period of
time. These two stations are located in the extreme southern
portion of the District and do provide an indication of trends in
the San Francisco Bay area. At San Rafael, mean oxidant values
have shown a definite decrease from peak values observed during
the mid 60' s. Annual means have dropped from around 5 pphm to
approximately 2 pphm in 1975. At Fairfield, the decreasing trend
is more difficult to discern from the mean values. However, peak
values have decreased since the early 70's. Other data available
for Petaluma, Napa, Eureka and Santa Rosa show no significant
trends .
366
Carbon monoxide data are only
Napa, San Rafael and Santa Rosa. Nine
sented in the appendix for San Rafael,
monoxide levels have been fairly
Peak values have shown a modest
16 ppm in 1975. Data at Santa
have also shown a slight decline
and Napa are not available for
from which to deduce more current trends.
available for Eureka,
years of data are pre-
At this station carbon
for at least six years .
from roughly 20 ppm to
the period 1972 to 1975
for the period. Data for Eureka
a significant period of record
constant
d e c 1 i n e ,
Rosa for
Sufficient data for sulfur dioxide are not available in
the Ukiah District to permit a long-term trend analysis. A
significant period of nitrogen dioxide data are available from
San Rafael. These data show little difference in mean NOo values
for the period 1969 through 1975, although values during this
period are lower than peak values observed in 1967 and 1968.
Nitric oxide values at San Rafael have shown a definite increase
from the low values observed during 1969 and 1970. Hydrocarbons
at San Rafael have shown a definite decrease in mean values since
the late 60's with very low values being observed in 1979 when
the peak value was 6 ppm.
Hi-volume data comprise the most readily available
source of pollutant data in the Ukiah District. Discernible
long-term trends are generally not. evident the fairly constant
levels observed in the northern part of the District. At Napa,
values have decreased during the four year period 1972 through
1975, and a decrease has also been noted at San Rafael.
367
5.4
POINT AND AREA SOURCES OF THE UKIAH DISTRICT
The Ukiah District encompasses counties in four air
basins - the North Coastal, the North Coastal Mountain, the
Sacramento Valley and the San Francisco Bay Area. This geograph-
ical distribution allows a diverse range of agricultural and in-
dustrial activities and settlement patterns. Industrial activi-
ties include rock aggregates, oil and shipyards. Timber and the
associated milling, veneer, plywood, redwood, pulp and paper
industries include grain warehouses and driers, sugar and rice.
These industries also comprise the bulk of major emitters (100
tons/yr or more) for the district. Other sizable emitters in-
clude West Sacramento and open burning dumps.
With many possible types of emitters, a wide range of
stack, flow and emission characteristics occur. Many of the
lumber and timber related industries do not have stacks. Equip-
ment includes bark boilers, crushers and kilns (with vents) which
emit pollutants. The temperature range for emissions from such
equipment is wide - from ambient (77°F) to 600°F. Other lumber
products are made more generally at 300-400°F. Typical emissions
from the lumber companies are particulates and carbon monoxide.
Particulate emissions fall in the 150-250 tons/yr range, with
carbon monoxide output reaching as high as 1500 tons/yr. Typical
carbon monoxide emission levels are 250-350 tons/yr. Table 5.4-1
provides a summary of typical source exit characteristics for a
variety of source types. These data can be used for simplistic
or screening level modeling as discussed in more detail in Sec-
tion 4.9.
There are a few large lumber industry facilities which
do not have stack data. Typically, however, there are 6 stacks,
80 feet tall (some range to 300 ft.) with diameters from 5 to 12
ft. and flow rates reaching 210,000 ACFM. Typical flow rates,
however, are 30,000 to 65,000 ACFM. Stack temperatures range
from 77°F to 465°F usually falling around 400°F. These plants
also typically emit carbon monoxide
pollutants; however, emissions of
tons/yr .
and particulates as principal
hydrocarbons can reach 150
There are few power plants in the district which are
major emitters. In the district, power facilities generally have
only one to two stacks with heights at about 120 feet and exit
diameters of around 10 feet. Typical exit temperatures are 320 F
with flow rates around 200,000 ACFM. Other industrial plants
(sugar, ports, warehouses and so on) and open burning dumps do
not have (or do not list) stack exit characteristics. Pollutants
commonly are TS P and NOx with some hydrocarbons and carbon monox-
ide. Most TSP emissions are in the 100-250 tons/yr range.
Figures 5.4-1 through 5.4-5 indicate the emission densities of
the criteria pollutants by county in the district.
The emission densities presented in Figures 5.4-1
through 5.4-5 are comprised of area and point sources. Area
sources comprise three principal types: solid waste disposal,
368
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II
ELK VALLEY
ARCATA
□
□
0 - 1,000
1,000 - 2,500
2,500 - 4,000
4,000 - 6,500
6,500 - 8,000
8,000 - 12,000
W. SACRAMENTO
Figure 5.4-1
Total Emissions of TSP (Tons/Year)
in the Ukiah District
370
ELK VALLEY
s
0 - 100
100 - 350
350 - 500
500 - 750
750 - 1,000
1,000 - 5,000
5,000 - 15,0C0
W SACRAMENTO
Figure 5.4-2
Total Emissions of Sulfur Dioxide (Tons/Year)
in the Ukiah District
371
ELK VALLEY
ARCATA
1,000 - 2,500
PI 2,500 - 5,000
5,000 - 10,000
10,000 - 12,000
12,000 - 18,000
W.SACRAMENTO
Figure 5.4-3
Total Emissions of Oxides of Nitrogen (Tons/Year)
in the Ukiah District
372
; VALLEY
ARCATA
□
15,000 - 25,000
25,000 - 40,000
40,000 - 75,000
75,000 - 100,000
100,000 - 120,000
Figure 5.4-4
Total Emissions of Carbon Monoxide (Tons/Year)
in the Ukiah District
W.SACRAMENTO
373
ELK VALLEY
ARCATA
1,000 - 5,000
5,000 - 10,000
10,000 - 20,000
20,000 - 25,000
> 25,000
W SACRAMENTO
Figure 5.4-5
Total Emissions of Hydrocarbons (Tons/Year)
in the Ukiah District
374
fuel sources other than factories (such as residences, institu-
tions and transportation) and evaporative losses from solvents
and gases. Major emitters in the Ukiah District are transporta-
tion, fuel, solid waste disposal, and depending on the county,
forest fires. Sonoma County also has significant solvent evapor-
ative hydrocarbon emissions - 6,476 tons/yr. Lake, Mendocino and
Sonoma counties have the greatest area emissions from total
suspended particulates - more than 2,400 ton/yr each. Solano
County has the largest emissions of sulfur oxides - 1,426 tons/yr
with Sonoma and Yolo Counties following in the 800 tons/yr range.
Marin, Solano and Sonoma Counties have the highest emissions of
NOx, HC and CO. On an overall district basis, the major area
pollutant is carbon monoxide at 613,226 tons/yr. Hydrocarbons
are the next highest with 127,945 tons/yr followed by NOx at
64,006 tons/yr. Point sources contribute more particulate and
more sulfur oxides than area sources.
Appendix F provides a summary of major point sources
within the District on a county basis. In the extreme north, in
Del Norte County, U.S. Forest Service operations at Six Rivers
represent the major point source in the region for all pollut-
ants. In Humboldt County, Crown Simpson Facilities at Fairhaven
are major emitters of suspended particulates, sulfur oxides,
nitrogen oxides and carbon monoxide. Louisiana Pacific facili-
ties at Somoa are also major emitters of these pollutants, with
the exception of sulfur dioxides. Pacific Gas & Electric's
facility at Humboldt Bay in Eureka, is a major emitter of nitro-
gen oxides while Areata Redwook in Orick is a prime contributor
to carbon monoxide levels. In Mendocino County, Georgia Pacific
at Fort Bragg is a major contributor to point source emissions of
carbon monoxide, hydrocarbons, nitrogen oxide, and particultes.
There are no major emitters of sulfur dioxide in the county. The
appendix indicates that no major emitters are located in Lake
County. Emissions are also very modest in Colusa County wi
th
only three point sources listed which barely qualify as major
emitters of suspended particulates. In Yolo County, the Rice
Growers Association West Sacramento River Plant is the major
emitter of total suspended particulates in the county on a point
source basis. The only contributor to the other criteria pollut-
ants is American Star Corporation's Spreckels Sugar facility at
Woodland. Napa County records only one major source and it
barely qualifies as a major emitter for particulates and sulfur
oxides. This is the Bay Salt Rock Company in Napa on the Vallejo
Highway. In the southeast, Sonoma County has several major
emitters, including the Masonite Lumber Company in Cloverdale
which is the major emitter of the criteria pollutants. Other
large sources include Cloverdale Lumber, Cloverdale Plywood and
the Louisiana Pacific Corporation all in Cloverdale. This city
is the home of many of the major point sources in the county.
Finally, there are no major point sources recorded in Marin
County .
375
Marin,
HC and
are the
concentrated
through 5.4-5 indicate, the counties of
have the largest emissions of CO, N02,
SOo. However, the counties with the highest TSP emissions
northern
As Figures 5.4-1
Solano and Sonoma
count i es
there .
due to the lumber industry which is
The Ukiah District is also the site of a special type of
natural and manmade air pollutants. The Geyser's Known Geother-
mal Resource Area (KGRA) is a major geothermal development area.
This area, depicted in Figure 5.4-6, is a source of emissions
associated with geothermal development, including well drilling,
testing, well bleeds, uncontrolled wells, stacking, pipeline
vents, and natural fumaroles. The plant emissions are the larg-
est source of hydrogen sulfide in the KGRA with natural fumaroles
accounting for only 0.3 percent of the total emissions (Weres, et
al , 1976). Plant emissions at Geysers Units 1 through 10 during
the fall of 1976 with a rated power of 396 megawatts. Geothermal
developments are also sources of carbon dioxide and sulfur diox-
ide. Other pollutants emitted in quantity include carbon monox-
ide, ammonia, boron, hydrogen, nitrogen, arsenic, radon and
mercury. The impact of some of the latter heavy metals is of
critical concern to biological species surrounding the large
cooling towers which must be used to dissipate heat at most
geothermal developments (Pacific Gas & Electric, 1979).
Figures 5.3-1 through 5.3-4 indicate the attainment
status of the various counties in the district. It is evident
that most of the district is subject to PSD for S02 and NOp. PSD
would also apply to ozone in all counties except for the Bay Area
counties, for CO for all counties except Marin, Napa, the Bay
Area portions of Sonoma and Solano, and Yolo, and for TSP for all
counties except Humboldt, Mendocino and Yolo.
The Bay Area counties will be subject to non-attainment
rules for oxidant and CO. Humboldt, Mendocino and Yolo will be
subject to non-attainment rules for particulates.
increments (see Section 6.4) will li
struction possible in the area, the
facilities and control equipment to be used tor projected emis-
sions. New Source Performance Standards will have to be con-
idered in conjunction with PSD and NESHAPS to provide a balance
etween developmental requests to utilize BLM lands and the
ecreational functions now substantially governing land use.
376
5.5 ASSISTANCE IN AIR POLLUTION PROBLEMS
REFERENCES
Abstracts
Air Pollution Control Association Abstracts
Air Pollution Control Association
4400 Fifth Avenue,
Pittsburgh, Pennsylvania
Public Health Engineering Abstracts
Superintendent of Documents
U.S. Government Printing Office
Washi ngton , D. C.
Periodicals
Air Engineering
Business News Publishing Company
450 W. Fort Street
Detroit, Michigan
Amer i can City
The American City Magazine Corporation
470 Fourth Avenue ,
New York , New York
American Industrial Hygiene Association
Journal
14125 Prevost
Det roi t , Michigan
American Journal of Public Health and Nations'
Health
American Public Health Association, Inc.
1790 Broadway
New York , New York
Archives of Environmental Health
American Medical Association
535 N. Dearborn Street
Chicago, Illinois
Atmospheric Environment
Pergamon Press
122 East 55th Street
New York, New York
Atmospheric Pollution Bulletin
Warren Spring Laboratory
Gunnels Wood Road
Stevenage , Engl and
377
Chemical Engineering
McGraw-Hill Publishing Company, Inc.
330 W. 42nd Street
New York, New York
Chemical Engineering Progress
American Institute of Chemical Engineers
345 47th Street
New York, New York
Chemical Reviews
American Chemical Society
20th and Northampton Streets
Easton, Pennsylvania
Environmental Health Series
National Centre for Air Pollution Control
4676 Columbia Parkway
Cincinnati , Ohio 45226
Heating, Piping and Air Conditioning
Keeney Publishing Company
6 North Michigan Avenue
Chi cago , Illinois
Industrial and Engineering Chemistry
American Chemical Society
1155 Sixteenth Street, N.W.
Washi ngton , D. C.
Industrial Hygiene Foundation of America,
Transactions Bulletin
Industrial Hygiene Foundation of
American, Inc.
4400 Fifth Avenue
Pittsburgh, Pennsylvania
Industrial Medicine and Surgery
Industrial Medicine Publishing Company
P.O. Box 306
Miami , FLorida 33144
Industrial Water and Wastes
Scranton Publishing Company, Inc.
35 E. Wacker Drive
Chicago , Illinois
Journal of the Air Pollution Control
Associ at i on
Air Pollution Control Association
4400 Fifth Avenue
Pittsburgh, Pennsylvania
378
Journal of Colloid Science
Academic Press, Inc.
Ill Fifth Avenue
New York , New York
Mechanical Engineering
American Society of Mechanical Engineers
345 E. 47th Street
New York , New York
The Oil and Gas Journal
211 South Cheyenne Avenue
Tul sa , Okl ahoma
Publ ic Heal th Reports
U.S. Department of Health, Education and
Wei fare
Public Health Service, Superintendent of
Document s
U.S. Government Printing Office
Washington, D.C. 20402
Public Works
Public Works Journal Corporation
200 South Broad Street
Ridgewood, New Jersey
Smokeless Air
National Society for Clean Air
Field House, Breams Building
London E. C . , England
Transaction of the American Society of
Mechanical Engineers
Journal of Engineering for Power (Series
A of the Transactions of the ASME)
Journal of Engineering for Industry
(Series B)
Journal of Heat Transfer (Series C)
Journal of Basic Engineering (Series D)
Journal of Applied Mechanics (Series E)
American Society of Mechanical Engineers
345 East 47th Street
New York 17, New York
Transactions of
Engineers
Institution of Chemical
16 Belgrave Square
London S. W. , Engl and
Institution of Chemical
Engi neers
Environmental Science and Technology
American Chemical Society
1155 Sixteenth Street N.W.
Washington, D.C. 20036
379
Books
Encyclopedia of Instrumentation for Industrial
Hygi ene , University of Michigan, Ann
Arbor, 1956.
Frenkiel, F.N.; and Sheppard, P. A. Editors,
Atmospheric Diffusion and Air Pollution,
Academi c Press , London , 1959.
Pub! ications
Air Pollution Abatement Manual Manufacturing
Chemists' Association, Inc.
1625 Eye Street, N.W. Washington, D.C.
The Air Pollution Bibliography
The Library of Congress Technical
Information Division Washington, D.C.
Air Pollution Control Association Abstracts,
Air Pollution Control Association
4400 Fifth Avenue
Pittsburgh, Pennsylvania
Applied Science and Tehcnology Index
The H.W. Wilson Company
950 University Avenue
New York, New York
Battelle Technical Review
Battelle Memorial Institute
505 Ki ng Avenue
Col umbus , Ohio
Chemical Abstracts
American Chemical Society
1155 Sixteenth Street, N.W.
Washi ngton , D.C.
Engi neer i ng Index
Engineering Index, Inc.
345 East 47th Street
New York, New York
on
Materials and
Environmental Effects
Equi pment
Prevention of Deterioration Center
National Academy of Sciences
National Research Council
2101 Constitution Avenue, N.W.
Washi ngton , D.C.
380
Meteorological and Geoast rophysi cal Abstracts
American Meteorological Society
45 Beacon Street
Boston, Massachusetts
Monthly Catalog of United States
Government Publications
Superintendent of Documents
U.S. Government Printing Office
Washi ngton , D. C.
Public Health Engineering Abstracts
Superintendent of Documents
U.S. Government Printing Office
Washi ngton , D. C.
Quarterly Cumulative Index Medicus
American Medical Association
535 N. Dearborn Street
Chicago, Illinois
Readers' Guide to Periodical Literature
The H.W. Wilson Company
950 University Avenue
New York, New York
Clearinghouse Announcements in Science and
Technol ogy
Category 68. Environmental Pollution and
Control .
CFSTI U.S. Dept. Commerce
Springfield, Va. 22151
Bibliographies
Air Pollution Publications - A Selected
Bibliography 1955 - 1963. Public Health
Service Publication No. 979.
Air Pollution Publications - A Selected
Bibliography 1963-1966. Public Health
Service Publication No. 979
Environmental Health Series Reports
Referencees and Abstracts. Public Health
Service, National Center for Air
Pollution Control, 1966.
Reference List of Publications. Section 1 Air
Pollution, Public Health Service,
National Center for Air POlltuion
Control. 1964
381
Carbon Monoxide - A Bibliography with
Abstracts. U.S. Dept. HEW, Public Health
Service. Publication No. 1503. 1966.
Sulfur Oxides and other Compounds - A
Bibliography with Abstracts, U.S. Dept.
HEW Public Health Service, Publicaiton
No. 1093. 1965
Nitrogen Oxides: An Annotated Bibliography
NAPCA Pub. No. AP-72, August 1970.
Hydrocarbons and Air Pollution: An Annotated
Bibliography. NAPCA PUb. No. AP-75
(Parts I , II ) , October 1970.
Photochemical Oxidants and Air Pollution: An
Annotated Bibliography. Pub. No AP-88
(Parts 1, 2), March 1971.
World Meteorlogical Organization-List of
Available Publications
WMO Publications Center
UNIPUB Inc.
P.O. Box 433
New York, N.Y. 10016
Professional Meteorological Consultants
Professional meteorologists advertise their services in
the Professional Directory section of the Bulletin of the Ameri-
can Meteorological Society. In the May 1979 Bulletin, 83 such
firms and individuals were listed. The American Meteorological
Society has in the last several years instituted a program of
certifying consulting meteorologists. Of the 83 professional
services listings in the Bulletin, 40 list Certified Consulting
Meteorologists.
Local U.S. National Weather Service Office
The Air Stagnation Advisories are received here by
teletype from the National Meteorological Center. Often the
public telephones the Weather Service with air pollution com-
plaints which the meteorologists may have traced back to a spec-
ific source by examining local wind circulations. Through per-
sonal contact with the meteorol ogi st- i n-charge (MIC) specific,
localized forecasts may be arranged to support a short-term air
pollution investigation or sampling program.
USEPA
The USEPA provides a complete information service to all
individuals, groups, companies, etc. This includes information
on regulations, publications as well as expert advice.
382
Contract Work
Many universities do contract work for private organiza-
tions and for government agencies on meteorl og i cal problems and
also on air pollution surveys.
333
5.6
GLOSSARY OF TERMS
Acetyl enes
Acid
Adhesi on
Aerosol
Aff i ni ty
Al cohol
Al dehyde
Al ert Level s
Al gae
Al kanes
Al kenes
Am ides
A group of unsaturated hydrocarbons whose
carbon atoms possess a triple bond.
A compound that turns blue litmus paper red,
generally tastes sour and most often is corro-
sive; in solution it produces hydrogen ions or
protons which can be replaced by metal to form
a salt. Acids usually contain hydrogen,
neutralized alkalis and form well defined
sal ts .
The force of attraction between unlike
cules, causing adjoining or attachment.
mol e-
A system of collodial particles dispersed in a
gas .
A natural liking or reaction; the phylogenetic
relationship between two organisms or groups
of organisms resulting in a resemblence in
general plan or structure; the force by which
atoms are held together in chemical compounds.
C?Hfi0 or C^HrOH, a volatile, colorless pungent
liquid; often used as a generic term which
met hoi al cohol , amy 1
includes ethyl alcohol,
al cohol and gl ycer i n .
Dehydrogenated alcohol.
A concentration of pollution which dictates
the issuance or notification by State Regula-
tory Agencies to the general public that a
threat to human health may occur due to ele-
vated pollution levels.
Simple aquatic plants without leaves, stems or
roots sometimes having brown or reddish pig-
ments.
The group of hydrocarbons in the methane
series, also called saturated hydrocarbons or
parafins (C-H).
A group of hydrocarbons with one double bond;
also called olefins or unsaturated hydrocar-
bons (C=C ) .
Organic compounds that contain the CO
radical or an acid radical in replacement
one hydrogen atom of an ammonia molecule.
NH2
for
384
Am i n e s
Amino Acids
Am phi bol e
Anaerobic
Anoxia
Aortic
Aqueous
Aromat i cs
Arteriosclerosis
Asbestos
Asphyxiant
Bi osphere
Ammonia bases, that is, chemical substances
resulting from replacing ammonia hydrogen
atoms with al kyl groups [(ChU) -N-H ]; amines
are products of animal or vegetable decompo-
sition.
Fundamental structural units of proteins; they
are fatty acids in which one hydrogen atom has
been replaced by an amino group.
Any of the complex group of the hydrous sili-
cate materials containing chiefly calcium,
magnesium, sodium, iron and aluminum, and
including hornblend, asbestos, etc.
Living in the absence of air or free oxygen.
Without oxygen, lack of oxygen for body use.
The conveyance of blood from the left ven-
trical of the heart to all of the body except
the 1 ungs .
Water acting as a solvent in a solution; a
fluid resembling water.
Any unsaturated hydrocarbon with cyclic mole-
cules resembling benzene, C^H^, in chemical
behavior, so named because of the fragrant
odor of many in the class.
An arterial disease characterized by an inel-
asticity and thickening of the vessel walls,
with lessened blood flow.
A fibrous amphibole used for making fire-proof
arti cl es .
An agent or substance which causes death or
loss of consciousness by the impairment of
normal breathing.
That portion of the world and its atmosphere
in which humans, animals and plants can sur-
vive.
Broncho-
constri ctor
Care i nogeni c
An agent that causes the contraction of the
muscles which control the pharynx.
Refers to a substance that is known to induce
cancer .
385
Catal ase
Catal yst
Catal yt ic
Convertor
Cation
Cel 1 ul ose
Chi orat i c
Mottle
Chi orosi s
Choi estrol
Chrysot i 1 e
Colloid
Cy pri nid
Di astase
Def ormat i on
Di scol orat i on
Di ssoc i at i on
The enzyme responsible for the decomposition
and oxidation of hydrogen peroxide into water
and oxygen.
A substance which accelerates or promotes a
chemical action by a reagent which itself
remai ns unchanged .
A device attached to an automobiles internal
combustion engine which chemically alters
emissions from the engine prior to release
through the exhaust system. The catalytic
convertor was introduced on modern-day automo-
biles in the mid-1970's in an effort to reduce
harmful automobile exhaust emissions and
promote a cleaner environment.
Ions of positive charge deposited on the
cathode .
The complex carbohydrate substance that forms
the material of cell walls of plants.
Brown or red spots on the surface of a leaf
caused by chemical pollution.
A diseased condition in green plants marked by
yellowing or blanching.
A sterol, C-^H^cOH, occurring in all animal
fat and oils, biTe, gall stones, nerve tissue,
bl ood , etc .
A fibrous variety of serpentine; asbestos.
A substnace in a state of matter characterized
by having small power of diffusion.
Any fish belonging to the minnow family;
carplike in form or structure.
The enzyme responsible for starch utilization.
The act of marring the natural form or shape
of an object; distortion.
The act or fact of changing or spoiling the
color of an object; a fade or a stafn.
The breaking up of a compound into its simpler
constituents by means of heat or electricity.
386
Ecosystem
Edema
Emi ssi on Density
Endogenous
Endotherm ic
Enzyme
Ester
Ether
Fauna
Fixation
Fl ora
Fl ourescence
Gl ucosidase
Greenhouse
Effect
A habitable environment existing naturally or
created artificially.
Effusion of serous fluid into the interstices
of cells, in tissue spaces or into body cavi-
ties.
Emissions per unit area.
Originating or developing internally or with-
in .
Noting or pertaining to a chemical change that
is accompanied by an absorption of heat.
A protein substance secreted in animals or by
plants whose function is catalytic, promoting
chemical reactions for metabolic or physiolo-
gical processes.
A compound produced by the reaction between an
acid and an alcohol with the elimination of a
mol ecul e of water .
A series of compounds formed by dehydration of
al cohol s .
Collective animal life of any prticular geo-
graphical area or time.
The act of making stable in consistence or
condition; reduction from fluidity or vola-
tility to a more permanent state.
Collected plant life of any particular area or
t ime .
Emitting radiation (such as light) as a result
of, and only during the time of, exposure to
radiation from another source.
The enzyme that catalyzes glucose.
Most of the infrared radiation emitted by the
earth is absorbed by carbon dioxide and water
in the atmosphere. Part of the infrared
radiaiton absorbed is re-radiated back to
earth. This trapping and recycling of terres-
trial radiation, which makes the earth warmer
than it would be otherwise, is known as Green-
house Effect, because it was once thought that
greenhouses remain warm by the same process.
387
Heavy Metal
Hematocrit
Hemogl obi n
Herbivorous
Homol og
Humus
Hydrate
Hydrol yze
Hypertrophy
Hyphai
I nert i al
I nsect i vorous
Intercostal Leaf
Area
Irradiation
A metal which is made up of elements having
1 arge atom ic wei ghts .
A centrifuge for separating the cells of the
blood from the plasma.
The protein coloring matter of the red blood
corpuscles, serving to convey oxygen to the
tissues and occurring in reduced form in
venous blood and in conbination with oxygen in
arter i al bl ood .
Feeding on plants.
An object corred spond i ng in structure and in
origin, but not necessarily in function, to
another object; chemicals of the same type,
but which differ by a fixed increment in
certain constituents.
The dark organic material in soil produced by
the decomposition of vegetable or animal
matter .
Compounds with large amounts of water as part
of their molecular structure and without re-
arrangement of the atoms of the H2O group;
hydration is the chemical union of water and
any substance.
To subject or be subjected to decomposition in
which a compound is split into other compounds
by taking up the elements of water.
An abnormal enlargement of a part or organ.
One of the thread-like elements of the vege-
tative part of f ung i .
Matter having the property by which it retains
its state of rest or its velocity along a
straight line so long as it is not acted upon
by an external force.
Adapted to feeding on insects.
Leaf area between the ribs.
The act of having been heated with radiant
energy; the act of having been exposed to
rad i at i on .
388
Irri tant
Ketones
Leach
Lichen
Macrophage
Marginal Leaf
Area
Mercaptan
Metabol i sm
Mi crodecomposer
Necrosi s
Ni tr i 1 es
Nucleation
Olefins
A biological, chemical or physical agent that
stimulates a characteristic function or elic-
its a response, especially an inflammatory
response .
A group of organic compounds characterized by
a carbonyl radical ( C = 0 ) united wih two
hydrocarbon radicals; usually colorless,
pungent substances .
A process by which a liquid filters through
another substance.
A plant composed of an algae and fungi growing
together .
A large cell that characteristically engulfs a
foreign material and consumes debris and
foreign bodies.
Leaf edges.
Compound analogous to alcohol containing
sulfur in place of oxygen (R-S-H).
The chemical activity that takes place in the
cells of living organisms involving two funda-
mental procedures, catabolism and anabolism,
simultaneously at work; the former refers to
the breaking up of substances into constituent
parts, the latter, building up of the sub-
stances from simpler ones.
Bacteria which breakdown waste material in
soil and in water as a prelude to the initi-
ation of a nutrient recycling process.
Death or decay of tissue.
Any of a class of organic compounds with the
general formula RC = N.
Any process by which a phase change
(condensation, sublimation, freezing) is
initiated at certain loci (points).
Members of a hydrocarbon group characterized
by the formula C Hpn and including ethylene,
propoylene and bu xylene; they are highly
reactive and can be formed by destructive
distillation of coal petroleum.
389
Organic Acids
Ox id i zer
Pathological
Peroxidase
Perox ides
Phenol
Photochem ical
Photon
Photopl ankton
Photosynthes i s
Phototox i cant
Podsal
Prec ursor
Acids which are usually derived from natural
or living sources .
A substance which causes the conversion of an
element into its oxide (which is accompanied
by an increase in oxidation number as opposed
to a reducing agent which promotes a decrease
in oxidation number); a substance which pro-
motes the covering of an element with a coat-
i ng of oxide or rust .
Caused by or involving disease.
A type or class of ox idored uctase enzymes that
causes the oxidation of a compound by the
decomposition of
organ i c perox ide .
hydrogen peroxide or an
A class of compounds containing oxygen and
other elements, with the Op group having a
valence of two (-) and acting like a radical.
A white crystalline solid obtained from the
distillation of tar; it is poisonous and
corrosive with a characteristically pungent
odor .
Refers to the effects of radiation, visible or
ultraviolet, upon chemical reactions.
A quantum of energy; a fundamental bundle of
radiation whose energy is directly propor-
tional to the frequency of the radiation.
The aggregate
ing organisms
most of their
of passively floating or drift-
in a body of water which derive
energy from 1 i ght .
The process by which green plants, containing
chlorophyll, with the aid of energy from the
sun, manufacture carbohydrates from water and
carbon dioxide.
A substance that is poisonous to plants.
An infertile, acidic forest soil having an
ash-colored upper layer depleted of colloids
and of iron and aluminum compounds, and a
brownish lower layer in which these colloids
and compounds have accumulated. fc
A person or object that goes before and indi-
cates the approach or something else.
390
Primary
Pol 1 ut ant
Progen i tor
Pulmonary
Pu 1 monary
Fi brosi s
Rad ical
Reactant
React i vi ty
Secondary
Pol 1 utant
Serpentine
Serum Lactate
Dehydrogenase
Si nk
Sorpt i on
Source
Spectroscopy
A pollutant in the form that it is released
from its source is considered a primary
pollutant as opposed to a secondary pollutant
which has undergone chemical change after
being emitted to the atmosphere.
An original or model for later developments;
predecessor; precursor.
Of or pertaining to the lungs.
A condition marked by an increase of inter-
stitial fibrous tissue in the lungs.
A combination of atoms that stay together and
take part in the chemical reaction as a unit
or a group as if it were a single element.
Any substance that undergoes a chemical change
in a gi ven react ion.
Pertaining to or characterized by reaction.
A pollutant is considered a secondary pollut-
ant if a chemical change has occurred subse-
quent to its release from its source.
A common mineral, hydrous magnesium silicate,
usually oily green and sometimes spotted,
occurring in many varieties, used for archi-
tectural and decorative purposes.
A class of oxide reductase enzymes that cata-
lyze the removal of hydrogen from the esters
or salts of lactic acid.
A lower state or condition.
The binding of one substance by another by any
mechanism, such as absorption, adsorption or
persorpt i on .
A place from which something comes, arises or
is obtained.
A procedure for observing the spectrum of
light or radiation from any source. Spectro-
scopy permits the examination and measurement
of the spectrum of radiant energy.
391
Stark-Einstein
Law
Stoi ch i ometry
Stunt i ng
S u 1 fate
Sulfide
Synerg i sm
Terpene
Thermodynamics
Tox i c i ty
Unci ass ifiable
Vol atile
A law of chemistry which states that one
proton must be absorbed by a substance to
initiate chemical decomposition.
Branch of chemistry dealing with weights and
proportions of elements in chemical combina-
tion and the methods of determining them.
Stopping or slowing down of the growth or
development of an object.
Chemical compounds (such as S03) created by
the photochemical reaction of sulfur dioxide.
Sulfates are secondary pollutants with import-
ant health and visibility effects.
A binary compound of sulfur with the valence
of two (- ) ; also a salt of hydrosul f ur i c acid.
The principal that a cooperative action be-
tween two agents - chemical and mechanical for
instance - results in an effect greater than
the sum of the two effects taken independent-
ly.
A series of hydrocarbons of the general for-
mula CiqHi,- found in resins.
Deals with the principals of conversion of
heat into other forms of energy and vice
versa .
The quality, relative degree or specific
degree of being toxic or poisonous.
With respect to air quality, unclassifiable
refers to those areas of the country which
cannot be a designated attainment or non-
attainment area due to insufficient baseline
air quality information.
Easily vaporized; tending to evaporate at
ordinary temperatures and pressure conditions.
392
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Nevada Mountains of California", Journal of the Air Pollu-
tion Control Association, 3/77, Vol. 27, No. 3, pp. 230-
TTT.
Yankel , A.J. et al. "The Siver Valley Lead Study: The" Relation-
ship between Childhood Blood Lead Levels and Environmental
Exposure", Air Pollution Control Association Journal 28(8),
August 1977, pp. 763-767.
399
6. AIR QUALITY REGULATIONS
6.1 EXECUTIVE SUMMARY
6.1.1 Bac kground
The Clean Air Act, as amended in 1977, is the primary
legislative tool for improving and monitoring air quality in the
United States. Many requirements of the Act apply to BLM activi-
ties, as well as to those of the Fish and Wildlife Service, the
National Park Service and the National Forest Service.
The Clean Air Act was originally passed in 1955 and
numerous Amendments have been initiated over the past 25 years.
Under the 1970 Amendments, for example, specific limits for
pollutant levels were established including dates for compliance.
These pollutant levels, called the National Ambient Air Quality
Standards (NAAQS) were based upon air "quality" effects on
health. The 1970 Act mandated the States to formulate plans to
achieve compliance with the ambient standards. These plans,
known as State Implementation Plans (SIPs), required State trans-
portation control plans, emissions limits for specific categories
of sources, and permit rules for new or modified sources of air
p o 1 1 u t i o n .
Once these plans were adopted by
by the EPA, they were binding as law.
jurisdictional authority to enforce the
plan. If a State was found by the EPA
administration of the plan, the EPA was
administer the plan until it felt that the
the State, and approved
The State then had the
regulations under the
to be deficient in its
able to i ntervene and
State could once again
resume adequate control of the program(s). It should be noted
that this concept has remained in the latest amendments to the
Act .
On August 7, 1977, Congress again passed amendments to
the Clean Air Act' (CAAA). These Amendments significantly altered
approaches to maintaining and achieving the adopted Air Quality
Standards. The three most substantial alterations to the Act are
considered to be (1) New Source Review Requirement (NSR) (2) Pre-
vention of Significant Deterioration (PSD), and (3) the require-
ment that States, by July 1979, again design programs (SIP) for
achieving the NAAQS. Note that items (1) and (2) are an integral
part of the State plan (3).
The CAAA also extended the original deadlines for
achieving the NAAQS to December 1982, with provisions for extend-
ing compliance to 1987 for areas with severe oxidant and/or
carbon monoxide problems. Furthermore Congress empowered EPA to
implement sanctions if a State did not have an acceptable SIP by
July 1979. The major sanctions that the EPA is able to impose
are to ban construction of major sources in non-attainment areas,
and to withold Federal funding for projects such as highway and
sewage facilities. As part of an acceptable SIP, a State which
400
requests an extension of the ozone and/or carbon monoxide com-
pliance date, must implement a statewide motor vehicle inspection
and maintenance (I/M) program.
A number of areas in California have requested an exten-
sion of the oxidant and CO NAAQS to 1987 (e.g., Los Angeles, San
Diego, etc.). However, due to the reluctance of the California
Legislature to adopt a statewise I/M program, the California SIP
is in jeopardy of being rejected. As of July 1, 1979, new major
sources (and certain modifications to existing major sources) are
prohibited from locating in non- atta i nment areas of the state.
Additionally, if the Legislature does not adopt an I/M program
prior to the time(s) EPA's conditional approval(s) expire, then
Federal Highway & Sewage funding will also be withheld.
6.1.2 Permit Rules for New or Modified Sources
Since 1970, the Clean Air Act has required that any new,
or modified source(s) of air pollution undergo a preconst ruct i on
rev i ew. The purpose of this review is to ensure that such
sources would not violate any ambient standard or contribute to
any existing violations of these standards. This review is known
as New Source Review, and has been expanded by the Amendments of
1977.
6.1.2.1 Nonatta i nment Areas
In nonatta i nment areas (areas that do not meet the
NAAQS), States are required to develop permit rules which meet
the requirements of the CAAA. Specifically, these permit rules
must require the following: (1) new or modified source locating
in a non-attainment area must obtain a high degree of emission
control (called Lowest Achievable Emission Rate or LAER) for the
problem pol 1 ut ant ( s ) , and (2) obtain emission reductions of that
pollutant, commonly called emission offsets or tradeoffs. Trade-
offs are generally obtained by retrofitting existing sources with
air pollution control equipment, or by "retiring" older units.
Because of the permit moratorium for nonattai nment areas, sources
wishing to locate in such areas may not receive permits until the
nonatta i nment portion of the SIP has been approved by the EPA.
The State of California has numerous non-attainment
areas and as such, a majority of the State Implementation Plan
consists of "plans" or "tactics" to bring the affected regions
(air basins) into compliance with the NAAQS.
6.1.2.2 Attainment Areas and Prevention of Significant Deteri-
oration Review
In attainment areas (areas in which the air quality is
better than the NAAQS), the Clean Air Act amendments require SIPs
to contain a special permit program for new or modified sources.
This permit program is called Prevention of Significant Deteri-
oration of air quality. As a result of this requirement, the
401
EPA, on June 19, 1978, promulgated the Prevention of Significant
Deterioration (PSD) regulations. The basic intent of these
regulations is to keep "clean air clean." This is accomplished
by placing ambient air quality limitations for
late matter in addition to the NAAQS which have
for these pollutants. The increase in ambient
these two pollutants from a given baseline
limited by what are called "increments." These
depending on the class designation of the area
or modified source is attempting to locate (see
S0? and
been
part l c u-
established
concentration of
concentration is
increments differ
in wh i ch the new
Fi gure 6.1-1).
three
The Clean Air Act and the
"classes" of clean air areas.
PSD regulations established
Each class has been assigned
numerical increments for particulate matter
concentrations; increments will be set in the
other criteria pollutants. These increments
to the ambient concentration increase above
tion which will be allowed in each particular
and sulfur dioxide
near future for all
indicate the limit
basel i ne concent ra-
" class" area.
Class I increments allow only minor air quality in-
creases; Class II increments allow a moderate amount of deteri-
oration; Class III increments allow the most air quality deter-
ioration, although violations of the NAAQS are never permitted.
Class I areas include national memorials and national wilderness
areas exceeding 6,000 acres in size.
Sources subject to PSD must use Best Available Control
Technology (BACT) on the proposed new sources or modified
sources, and furthermore, must demonstrate that the emissions
will not result in concentrations in excess of the PSD increments
for SOp and particulate matter. The most important aspect of
these regulations is that increment consumption is viewed from a
cumulative viewpoint. That is, if a source consumes part of the
increment, then the next source to apply for a permit(s) must
work within the remaining portion of the increment. Thus, it is
possible for the increment to be "used up" in a particular area.
Increment consumption is granted on a first-come, first-serve
basis.
6.1.2.3
Role of
Process
the Federal Land Manager in the Permit Review
Federal Land Managers (FLM) have input to
mitting process if a project will have an impact
area. Once a source makes an application to the
must make a determination as to the probable impact
will have. As early as possible, the EPA must conta
priate FLM if it is thought that the project will h
on a Class I area. The FLM may then review all
studies performed in conjunction with the EPA permi
within the 60 day review period. If the FLM fi
facility would have an adverse impact on the "air qu
values" of the land area, a permit cannot be issued
must then demonstrate that no adverse impact would o
the PSD per-
on a Class I
EPA, the EPA
s the project
ct the appro-
ave an impact
air quality
t eppl i cat i on
nds that the
al i ty related
The source
ccur. Denial
402
4->
C
4J
CD
E
CD
S~
u
c
100-
80-
CD
E
<D
S-
c
100-
80-
qj
jO
fO
o
60-
40-
40
QJ
03
2
O
60-
40-
<
p
20-
20
5
E
3
E
X
A3
20-
3
E
0— .
2
0-
X
u J
Class I
Clc
1SS
II
Class
III
Sulfur Dioxide
Annual Geometric Mean
1 100-
i-
c 80-
60- -
QJ
X>
re
| 40-
= 2^
13
X
0-
25
91
182
Class I Class II Class III
Sulfur Dioxide
24-Hour Maximum
Class I Class II Class III
Sulfur Dioxide
3-Hour Maximum
+->
c
QJ
I loo-
i-
u
,5 80-
QJ
S 60-
I 40- -
E
13
^E
X
to
20- -
0-
19
37
Class I Class II Class III
Particulate Matter
Annual Geometric Mean
4->
c
QJ
E
QJ
S-
(J
c
QJ
TO
O
X
100-
80-
60-
40-
20-
0-
A
75
37
Class I Class II Class III
Particulate Matter
24-Hour Maximum
Figure 6.1-1
Prevention of Significant Deterioration
Maximum Allowable Increments as a Function of Class Designation
( yg/m3 )
403
by the FLM may be made
Class I increments will
even if it has been demonstrated that the
not to be exceeded by the project.
It is also important to note that if the FLM proposes
activities on land within his jurisdiction, the available incre-
ment must not be exceeded. This may inhibit future land manage-
ment decisions, and should be considered in the early part of the
decision process.
6.1.2.4
Rol e of the
Proced ure s
Federal Land Manager in Class Redes i gnat i on
The FLM also has a minor role in the process of redesig-
nating a particular class area (for example, a Class II area to
be redesignated to a Class I area). Redes i gnat i ons may only be
proposed by the state or by an Indian Governing Body. If the
area to be redesignated contains Federal lands, the FLM is to be
notified of the proposal. The FLM will be allowed to comment on
the proposal, and if he is opposed to it but the State wishes to
continue to pursue it, he must be provided with an explanation of
the reasons why the State feels it should be redesignated. The
FLM may also provide input at the public hearing which is re-
quired for all redes i gnat i ons ; however, the State has the ulti-
mate authority.
6.1.3
Visibility Protection
The 1977 Amendments added to the Clean Air Act a section
entitled "Visibility Protection for Federal Class I Areas". This
section declares as a national goal "the prevention of any fu-
ture, and the remedying of any existing, impairment of visibility
in mandatory Class I Federal areas" where impairment results from
man-made air pollution. Such a list of Mandatory Class I federal
areas was first published in the November 3, 1977 Federal Regis-
ter and was revised on Nov. 30,1979. Those areas so designated
are presented in Table 6.4-2 and Figure 6.4-1, respectively. The
Amendments also required that by February 1978, the Secretary of
Interior, in consultation with the States and the FLM's, identify
any mandatory Class I areas where visibility contributes signifi-
cant value to that particular area. These areas were published
in the February 24, 1978 Federal Register. As such, all Class I
areas are areas in which visibility is an important value. The
EPA, by February 1979, was to have completed a study and report
to Congress on available methods for implementing this national
goal. This document was not available in time to be addressed in
this report. Additionally, the EPA was authorized to promulgate
regulations requiring retrofits on specified pieces of equipment
so that visibility would be maintained, or enhanced. The FLM
must be consulted with regard to these regulations.
6.1.4
Emission Standards
The Clean Air Act gave the EPA the authority to promul-
gate emission standards for specific categories of equipment. It
404
also gave EPA the authority to designate certain pollutants as
"hazardous", and to set emission standards for such hazardous
pollutants for specific categories of equipment.
The EPA has promulgated New Source Performance Standards
(NSPS) and National Emission Standards for Hazardous Air Pollut-
ants (NESHAPS). The NSPS standards presently consist of emission
limits of pollutants for 28 sources categories. The NESHAPS have
been established for mercury, beryllium, asbestos, vinyl and
chloride (a NESHAPS for benzene has been proposed).
6.1.5
State Regul at i ons
6.1.5.1 Perm it Rules
As previously discussed, a major intent of the Clean Air
Act was to establish procedures for permit rules, and require
States to adopt such rules as part of their SIP. Until such time
as these rules are approved by the EPA, and incorporated in the
SIP, the EPA still retains permitting authority over affected
sources .
The lead State agency in California is the Air Resources
Board (ARB). ARB is responsible for coordinating the SIP and has
exclusive authority over mobil sources. Additionally, it moni-
tors local agencies (County Air Pollution Control Districts)
activities over stationary sources, and also conducts compliance
tests .
ARB also adopts modal rules governing all sources, and
encourages the local districts to adopt similar rules, so that
there is a degree of uniformity throughout the State. Note,
however, as discussed in Section 6.5, local districts tend to
adopt rules which reflect the nature of the area (i.e., indus-
trial vs . rural ) .
405
6.2
THE ROLE OF THE FEDERAL LAND MANAGER
As defined in the Clean Air Act Amendments of 1977, the
Federal Land Manager (FLM) for the BLM has the responsibility to
protect the air quality related values of lands within his juris-
diction. This responsibility must be addressed in a number of
programs including protection of visibility, fire management, oil
and gas leasing, land use planning of Federal lands, issuance of
right-of-way permits, and the preparation of Environmental Impact
Statements (EIS's) attendant to such permits. Land management by
the BLM is primarily concerned with recreational areas ( e.g.,
wilderness areas) but the concerns of the Land Manager are cer-
tainly not limited to these aspects. For example, oil wells, or
gas pipelines which are on Federal lands, come under the juris-
diction of the FLM. In order for the Manager to issue a BLM
permit for such activities, he must ascertain that the owner or
operator of the project has obtained all necessary State, local
and Federal permits. These include environmental permits in many
cases. Thus, it is imperative for the FLM to be familiar with
the legislative and regulatory aspects of air quality in addition
to the baseline meteorology and air quality with which the permit
is concerned. An understanding of the rudiments of the air
quality review processes in California can be helpful in the
preparation of future EIS's, since many applicants are required
by law to prepare air quality assessments to obtain project
approval. Such assessments could be used by the FLM in prep-
aration of an EIS and in making a final decision.
In recent years, the role of the FLM in the protection
of air quality has increased. Recent federal legislation has
provided increasingly stringent restrictions to protect the clean
air resource from further deterioration by new or modified
sources. The 1977 Amendments require the FLM to take an active
role in the EPA's PSD permit process. Specifically, the Clean
Air Act has given the FLM the authority to comment on projects
which impact the air quality in areas designated as Class I
(i.e., national parks, monuments or wilderness areas in excess of
6,000 acres, or any other area designated by the State as a Class
I Area). In the words of the Act, the FLM must actively protect
the "air quality related values, including visibility" of such
lands and may oppose programs felt to be deleterious to Class I
areas. The Act also authorizes the FLM to take an affirmative
role in visibility protection in these areas, as well as taking
part in altering the Class designation of any area incorporating
federal lands.
Because "air quality related values" are one of the
concerns of the FLM, it is necessary that the Managers be fam-
iliar with the implications of clean air legislation as it af-
fects Federal lands. Section 6.3 discusses the Federal legis-
lative history concerning air pollution provisions of the 1977
Amendments pertinent to Federal land areas and visibility pro-
tection, and also indicates where the FLM may participate in the
implementation of such provisions.
406
6.3
HISTORY OF AIR QUALITY LEGISLATION
Public concern for the nations air quality and for the
effect that polluted air has on human health and welfare led to
the passage of National Air Pollution Legislation in 1955.
Amendments to this legislation were passed in 1963, 1965, 1967,
1970 and 1977 (Table 6.3-1 is a list of clean air legislation
enacted by the Federal Government). Prior to the 1970 amend-
ments, the responsibility for air quality was held by the States
with the Federal Government providing little more than financial
and technical assistance. Some progress toward cleaner air was
achieved; however, in the opinion of a significant portion of the
population, it was insufficient. As a result, the 1970 Amend-
ments introduced the Federal Government as a regulatory force.
The States remained responsible for developing air quality Imple-
mentation Plans but, under the 1970 Amendments, specific limits
were set and certain pollutant concentration levels had to be
achieved by stipulated dates. The specific concentration levels
are called the National Ambient Air Quality Standards (NAAQS).
Two types of NAAQS were mandated by the Amendments of
1970. Primary standards set levels which allow an adequate
margin of safety for public health while Secondary standards
specify levels which protect the public welfare from any known or
anticipated adverse effects associated with a pollutant's pres-
ence in the ambient air. Secondary effects on public welfare
refer to impacts on soils, water, crops, visibility, as well as
effects on economic values and on personal comfort and well
being. Table 6.3-2 shows the standards at current levels. As
can be seen, the secondary standards are, in most cases, more
stringent, due primarily to the wide range of items included
under 'public welfare' which the secondary standards must pro-
tect .
The 1977 Amendments attempted to deal with controversies
that had developed concerning achievement of the regulations and
the overall achievement of the goals of the Clear Air Act. The
energy shortage and the cost and development of air quality
control equipment on both stationary and mobile sources caused
industry to seek delays in achieving mandatory standards. Envir-
onmental organizations, through the use of the judicial system,
had forced the EPA to promulgate legislation to prevent the
significant deterioration of air quality in regions of the coun-
try where the air was cleaner than the established standards.
Promulgation of the original PSD regulations brought opposition
from persons concerned about such issues as industrial growth,
employment, the economy and EPA authority. These and other
concerns influenced the Congress to consider amending the Clean
Air Act to establish new deadlines for achieving certain stan-
dards and to resolve the PSD issue. s-
407
Table 6,3-1
Clean Air Legislation Enacted by the Federal Government
Date
Public Law
Purpose of Law
6/55
9/59
6/60
12/63
10/65
10/66
11/67
12/69
12/70
6/74
8/77
84-159
86-365
86-493
88-206
89-272
89-675
90-148
91-190
91-604
93-319
95-95
Provide research and technical assistance
relating to air pollution control.
Extend the Federal Air Pollution Control Law
PL 84-159.
Direct the Surgeon General to study and report
on health effects of automobile emissions.
Improve, strengthen and accelerate programs for
the prevention and abatement of air pollution.
(Title: Motor Vehicle Air Pollution Control Act)
Require standards for automobile emissions and
authorize research in solid waste disposal
programs .
(Title: Clean Air Act Amendments of 1966).
Authorize grants to air pollution control
agencies for maintenance of control programs.
(Title: Air Quality Act of 1967). Authorize
planning grants, expand research relating to
fuels, and authorize air quality standards.
(Title: National Environmental Policy Act).
Establish the Council on Environmental Quality,
direct Federal agencies to consider environ-
mental quality regulations.
(Title: Clean Air Act Amendments of 1970).
Provide a more effective program to improve
the quality of air.
(Title: Energy Supply and Environmental
Coordination Act). Provide means of dealing
with the energy shortage.
(Title: Clean Air Act Amendments of 1977).
Requires BACT review on a much expanded basis.
Established PSD requirements. Required
v i s i b i 1 i ty be considered.
408
Table 6.3-2
National Primary and Secondary Ambient Air Quality Standards
Air Contaminant
Averaging Time
Federal Primary
Standard
Federal Secondary
Standard
Nitrogen Dioxidel/
Sulfur Dioxide
Suspended
Particulate
Hydrocarbons
(corrected for
Methane )
Photochemical
Ozone (oxidant)
Carbon Monoxide
Lead
Annual Average
Annual Average
24-Hour
3-Hour
Annual
Geometric Mean
24-Hour
3-Hour
6-9 a.m.
1-Hour
8-Hour
1-Hour
30-Day
100 ug/m"3
(0.05 ppm)
80 yg/m3
(0.03 ppm)
365 yg/m3
(0.14 ppm)
75 yg/nr
260 ug/m3
160 yg/m3
(0.24 ppm)2_/
240 yg/m3
(0.12 ppm)
10 mg/m3
(9 ppm)
40 mg/m3
(35 ppm)
1 . 5 yg/m3
100 yg/m3
(0.05 ppm)
1300 yg/m3
(0.5 ppm)
60 yg/m3
150 yg/m3
160 yg/m3
(0.24 ppm)
240 yg/mJ
(0.12 ppm)
10 mg/m3
(9 ppm)
40 mg/m3
(35 ppm)
Source: 38 Code of Federal Regulations 25678, September 14, 1973
NOTE: ppm = parts per million
ug/m3 = micrograms per cubic meter
mg/m3 = milligrams per cubic meter
j_/ Nitrogen dioxide is the only one of the nitrogen oxides
considered in the ambient standards.
2/ Maximum 3-hour concentration between 6-9 a.m.
409
6.4
SUMMARY OF THE CLEAN
RELATED REGULATIONS
AIR ACT AMENDMENTS OF 1977
AND
1977
to th
i cant
ment .
p r o v i
attai
schem
n a t i o
regul
regul
cusse
compr
1974.
Pres i dent Carter
(PL 95-95) into law
e Clean Air Act Part
Deterioration (PSD)
signed the Clean Air Act Amendments of
on August 7, 1977. The Amendments add
C, concerning the Prevention of Signif-
of air quality and visibility enhance-
Part B adds a section on ozone protection. Part D adds
sions for State Implementation Plan requirements for non-
the PSD section establishes a
air quality cleaner than minimum
the EPA to promulgate a permit
sources in such areas. Such
June 19, 1978 and will be dis-
regulations are generally more
in
nment areas. In general,
e for protecting areas with
nal standards and requires
ation for new or modified
ations were promulgated on
d more fully below. These
ehensive than those originally promulgated by the EPA
The amendments continue the use of two major control
schemes designed by the 1970 amendments: National Ambient Air
Quality Standards (NAAQS) and New Source Performance Standards
(NSPS). In the five year period from January 1971 through Jan-
uary 1976, the EPA promulgated emission limits, or NSPS, for 19
source categories. The Amendments of 1977 increased the 19
source categories to 28. Additionally, the 1977 Amendments
require EPA to update NSPS every four years.
6.4.1
National Ambient Air Quality Standards (NAAQS)
As mentioned above, the Clean Air Act amendments of 1970
mandated the EPA to promulgate primary and secondary NAAQS. The
1977 Amendments require that the EPA complete, by December 31,
1980, and at five-year intervals thereafter, a thorough review of
air quality criteria, and that, if appropriate, the National
Ambient Air Quality Standards be revised. The EPA is also manda-
ted to promulgate a NAAQS for N0? concentrations over a measure-
ment period of not more than three hours. This was originally
due by August, 1978, but the EPA has not as yet issued such a
regulation. If the EPA finds that there is no significant evi-
dence that such a standard is needed to protect public health,
such a standard will not be required to be promulgated (the Nov.
30, 1979 Federal Register indicated this decision would be made
by May 1, 1980).
6.4.2
Designation of Attainment Status
The Clean Air Act Amendments of 1977 required that by
December 6, 1977, every State submit to the EPA a listing of the
attainment status of its Air Quality Control Regions (AQCR's) for
each of the six pollutants for which a NAAQS has l>een estab-
lished. In the March 19, 1979 and Sept 11th and 12th, 1979
issues of the Federal Register, a re-listing of all nonatta i nment
areas, by state, were published. If an area has air quality
better than the NAAQS for S09 and TSP, it will be designated as
410
an attainment area; if air quality is worse than the NAAQS, it
will be designated as a nonatta i nment area. AQCR's may be sub-
divided with areas designated as "attainment", as well as areas
being designated as "nonatta i nment " . Areas for which there is
insufficient information to determine whether the standards have
been met will be designated as "unable to classify." Attain-
ment/ nonatta i nment designations will be made on a pollutant-
specific basis. Thus, an area may be an attainment area for one
pollutant, and a nonatta i nment area for another pollutant.
6.4.3
State Implementation Plans
The 1977 Amendments retained the use of the State Imple-
mentation Plan (SIP) which was originally introduced in the 1970
Amendments. All SIPs will have to be revised to implement the
standards and regulations mandated by the Amendments. The SIPs
as originally devised in the 1970 Amendments required transpor-
tation control plans, emission limits for specific categories of
sources, and permit rules for new or modified sources of pollu-
tion. The goal of these plans, as stated above, was to ensure
that the NAAQS would be met in all areas of the country.
As stated previously, the 1977 Amendments expand upon
the SIP requirements, and differentiate between two different
pi an types :
• Areas in which the NAAQS are being met (attainment
areas )
t Areas in which one or more of the NAAQS are being vio-
lated (nonatta i nment areas)
Thus, a State may have to address both concepts in developing its
State Implementation Plan.
6.4.3.1 Nonatta i nment Areas
Under the new Amendments, States containing nonattain-
ment areas must have submitted to the EPA by July 1, 1979, an
approvable implementation plan which provides for attainment of
primary standards by December 31, 1979. The plan must provide
for the implementation of "reasonably available control measures"
on existing stationary sources to be determined by the State.
If, despite these "reasonable available control measures", a
State cannot attain primary standards for carbon monoxide or
photochemical oxidant before the 1982 deadline, it may request an
extension to 1987. To be eligible for an extension, a vehicle
inspection and maintenance program must be adopted by that State.
The Amendments also made specific requirements regarding
permit rules. Since 1970, the Clean Air Act has required that
any new or modified source of air pollution must undergo a pre-
construction review. The purpose of this review is to ensure
411
that such sources would not violate any ambient standard or
contribute to any existing violations of these standards. This
review is known as New Source Review.
The Amendments require that in nonatt a i nment areas, the
SIP must also contain permit requirements for the review of new
the requirement for such
or modified sources which would include
sources to achieve a "Lowest Achievable
that particular source and pollutant,
offsets for that particular pollutant
proj ect .
Emission Rate" (LAER) for
and to secure emission
in the locality of the
Most importantly, the Amendments impose a permit mora-
torium. No permits may be issued in a nonatta i nment area (nei-
ther by the State nor the EPA) after July 1, 1979 unless a SIP
for that area has been approved by the EPA. Thus, sources wish-
ing to locate in such areas may not receive permits until the
nonatta i nment portion of the SIP for that area has been approved
by the EPA. Numerous States did not comply with the SIP time
frames established by the Clean Air Act Amendments and on
November 23, 1979, EPA announced that conditional approvals for
SIP's would not be extended past the time the States were ori-
ginally given to correct any SIP deficiencies. No second condi-
tional approvals would be given, and in those cases where a State
has failed to meet a scheduled commitment date - the SIP would be
rejected, and the sanctions authorized under the Act would be
imposed.
The lead state agency in California is the Air Resources
Board (ARB). ARB is responsible for coordinating the SIP and has
exclusive authority over mobile sources. Additionally, it moni-
tors local agencies (County Air Pollution Control Districts)
activities
tests .
over stationary sources, and also conducts compliance
sources , and
rules, so that
Note,
tend to
i nd us-
ARB also adopts modal rules governing all
encourages the local districts to adopt similar
there is a degree of uniformity throughout the State,
however, as discussed in Section 6.5, local districts
adopt rules which reflect the nature of the area (i.e.
trial vs. rural).
6.4.3.2 Attainment Areas
• Prevention of Significant Deterioration (PSD)
The 1977 Amendments kept active the concept of PSD.
This is a permit rule which must be incorporated into
SIPs for attainment areas. It applies to specific
sources which are named in the Clean Air Act and the
EPA's subsequent regulation. It is essentially a New
Source Review rule for those sources in attainment
areas, or in those areas which have been designated as
"unable to be classified", according to Section 107 of
the Clean Air Act as amended.
412
Unlike the nonatta i nment areas, there is no permit
moratorium imposed. The failure of a State to adopt
into their SIP a permit rule incorporating the PSD
requirements of the Clean Air Act, does not impose a
moratorium on permits. Thus, if a SIP is not approved
by the EPA in an attainment area , sources will be re-
quired to obtain such permits from the EPA, as well as
obtaining any permits required by the State. When the
State adopts a PSD-type rule which is approved by the
EPA, then the State has the jurisdictional authority to
administer it, and a source need only obtain the State
permit .
The basic intent of the PSD regulations is to keep
"clean air clean". This is accomplished by placing
limitations on the amount that pollutant concentrations
can be increased above what is termed "baseline concen-
tration". This will be discussed in further detail
bel ow.
Classification of Attainment Areas under PSD
The Clean Air Act, and subsequent PSD regulations desig-
nate all attainment areas as either Class I, II or III,
depending on the degree of deterioration that is to be
allowed. Limits are assigned to increases in pollution
concentrations for S0~ and particulate matter for each
classification (See Table 6.4-1). Class I increments
allow only minor pollutant concentration increases while
Class III increments allow the most concentration in-
creases. However, in no instance may the NAAQS be
exceeded .
Congress specified that certain areas were to be auto-
matically designated Class I. These areas include
national memorials, parks and wilderness areas exceeding
6,000 acres in size, already in existence by the date of
enactment. A list of the Class I areas for California
are presented in Table 6.4-2 and illustrated in Figure
6.4-1 (this may be viewed in conjunction with overlay
G). These areas may not be redesignated.
Under PSD regulations, the remaining areas are all
These areas may be redesignated by
Class I or Class III, following the
in the regulations, and which will
FLM's role in the Redesi gnat i on of
All new Wilderness Areas must be
CI ass I or II.
presently Class II.
the states to either
procedures outl i ned
be discussed in the
Area Classifications
designated as either
Applicability and Review Requirements
On June 19, 1978, the EPA promulgated the requirements
for PSD as required in the Clean Air Act Amendments of
413
Table 6.4-1
Prevention of Significant Deterioration
Maximum Allowable Increments
(In Micrograms Per Cubic Meter)
Pol 1 utant
Class I
Class II
Class III
Particulate Matter
Annual Geometric Mean
24-Hour Maximum*
5
10
19
37
37
75
Sulfur Dioxide
Annual Arithmetric Mean
24-Hour Maximum*
3-Hour Maximum*
2
5
25
20
91
512
40
182
700
*May be exceeded once per year
414
Table 6.4-2
Mandatory Class I Areas Under 1977
Clean Air Act Amendments for California
National Parks
Kings Canyon
Lassen Volcanic
Redwood
Sequoi a
Y o s e m i t e
National Wilderness Areas Over 6,000 Acres
A g u a Tibia
Caribou
Cucamonga
Death Valley
Desol ation
Dome Land
Emigrant
Hoover
Joshua Tree
John Mui r
Kai ser
Lava Beds
Marble Mountain
Mi n a rets
Mokel umne
Pinnacles
Point Reyes
Salmon Trinity Alps
San Gabriel
San Jacinto
San Rafael
South Warmer
Thousand Lakes
Ventana
Yolla-Bolly Middle Eel
415
ELK VALLEY
Redwood National Park
ARCATA
ONLY THE WILDERNESS
PORTIONS ARE DESIGNATED
CLASS I
W SACRAMENTO
Point Reyes National Seashore*
Figure 6.4-1
Mandatory Class I Areas Under 1977 Clean Air Act Amendments
416
1977. The following discussion is based on the PSD
requirements as contained therein. Appendix H contains
a summary analysis of the June 18, 1979 decision by the
United States Court of Appeals,
Alabama Power Co. versus USEPA.
cantly impact PSD
dix. It should
Court i ssued its
lations; however,
that decision is
D.C. Circuit regarding
This case will signifi-
indicated in the Appen-
in December, 1979, the
regarding the PSD regu-
due to time constraints an analysis of
not incorporated in this report.
regulations as
be noted that
final decision
The CAAA of 1977 gave detailed requirements to assist
states in the modification of their SIP's to conform
with the Amendments. Twenty-eight source categories
have been specified as subject to the PSD regulations
and are listed in Table 6.4-3. A source included in the
28 source categories having potential emissions (uncon-
trolled) greater than 100 tons/yr for a pollutant i s a
major PSD source for that pollutant, (provided the area
in which the source is locating has been classified as
attainment for that pollutant; otherwise, it is subject
to nonattainment rules).
In addition to the 28 categories specified, there is
also a "catch-all" category. Sources having potential
(uncontrolled) emissions greater than 250 tons/yr are
major PSD sources for that pollutant (provided, once
more, that the area in which the source is locating is
an attainment area for that pollutant).
Major PSD sources must apply Best Available Control
Technology (BACT) for each applicable pollutant and
undergo an air quality analysis. BACT means an emission
limit or control technology representing the maximum
degree of reduction with respect to a particular source
and pollutant, taking into account energy, environmental
and economic impacts, and technical feasibility. This
determination is made by the EPA, but demonstration made
by the Applicant will be considered.
If, after application of BACT, the pollutant levels are
greater than 50 tons/yr, 1,000 lbs/day or 100 Ibs/hr
(whichever is the most stringent), an air quality analy-
sis must be performed. The PSD regulations require that
a source demonstrate that no violations of NAAQS for
NOp, CO and HC will occur (assumed that the area under
consideration is in attainment for these pollutants).
While NO-, CO and HC concentrations can, in effect, be
increased to the respective NAAQS, SO^ and particulate
matter increases are limited by " increments- above the
"baseline concentration". The "increments" are defined
by the PSD Class designation for the area in which the
source is located.
417
Table 6.4-3
PSD Major Stationary Sources
Potential Emission of Any Pollutant Greater than 100 tons/yr
Fossil-Fuel Fired Steam Electric Plants
(More than 250 MMBTU/Hr Input)
Coal Cleaning Plants (with Thermal Dryers)
Kraft Pulp Mills
Portland Cement Plants
Primary Zinc Smelters
Iron and Steel Mill Plants
Primary Aluminum Ore Reduction Plants
Primary Copper Smelters
Municipal Incinerators
(Capable of Charging More than 250 Tons Refuse/Day)
Hydrofluoric, Sulfur and Nitric Acid Plants
Petroleum Refineries
Lime Plants
Phosphate Rock Processing Plants
Coke Oven Batteries
Sulfur Recovery Plants
Carbon Black Plants (Furnace Process)
Primary Lead Smelters
Fuel Conversion Plants
Sintering Plants
Secondary Metal Production Plants
Chemical Process Plants
Fossil Fuel Boilers (or Combinations Thereof)
(With Total Storage Capacity Exceeding 300 Thousand BBLS)
Taconite Ore Processing Plants
Glass Fiber Processing Plants
Charcoal Products Plants
and
Notwithstanding the sources above, any source which emits
or has potential to emit 250 tons/yr or more of any
pollutant regulated under the act.
418
Baseline concentration is essentially the air quality,
or concentration level of SO.? and particulate matter
that "existed" on August 7, 1<T77. Thus, the emissions
from a proposed source are "modeled" via computer simu-
lation, and a concentration prediction is obtained. The
S0? and/or particulate matter concentration obtained
must not exceed the incremental PSD limit for the area
in which the source is locating; furthermore the concen-
tration obtained (or "used") is applied against the
i ncrement . This means increment consumption is cumula-
tive. That is, if emissions from the source result in
S0? and particulate concentrations which consume part of
the increment allowed from the "baseline concentration",
then the next source(s) to apply for PSD permits must
work within the remaining increment (See Figure 6.4-2).
It should be noted that SOo and particulate concentra-
tions are prohibited from exceeding the NAAQS. Thus, if
a "baseline concentration" is close to the NAAQS, and
the additional "increment" defined by the values in
Table 6.4-1 would exceed the NAAQS, then NAAQS becomes
the upper limit, and the increment is "reduced"
accordingly.
Federal Land Manager's Role in Class I Area Reviews
• Denial; impact on air quality related values
FLM's have input to the PSD permitting process if a
project is believed to have an impact on a Class I area.
Once a PSD application is submitted, the EPA must con-
tact the appropriate FLM if it is believed that the
project will have any air quality impact on a Class I
area .
If the FLM finds that emissions from a proposed facility
would have an adverse impact on "air quality related
values" (which include visibility) of the land area
(even though allowable Class I increments would not be
exceeded), he can recommend to the EPA that the permit
be denied. If
t i on , a perm it
the EPA concurs with
wi 1 1 not be i ssued .
the FLM s demonstra-
Class I variances
Conversely, in a situation where Class I increments are
predicted to be exceeded, the applicant may appeal to
the FLM. The applicant must demonstrate to the FLM that
the emissions from the facility will not adversely
impact air quality related values. If the FLM concurs
with this demonstration, he must certify this concur-
rence, and the state may then authorize the EPA to issue
a permit which would allow the facility to comply with
less stringent air quality increments. In such cases,
419
NAAQS
A/Q 8/7/77
NAAQS
Maximum AT low-
able Limit
A/Q 8/7/77
Baseline Concentration
is the Air Ouality of
Pollutant as of 8/7/77
PSD Increment for SO2 or
Particulate Added to Base
line Establishes Upper
Limit Under PSD. The
NAAQS is the Upper Limit
in All Cases and Cannot
be Exceeded
NAAQS
NAAQS
Maximum Al low-
able Limit
As Sources Are Permitted
Under PSD, Their Concen-
trations of SO2 or Parti-
culate Consume Increment
Each Succeeding PSD Source
to Apply for Permit has
Increasingly Less Incre-
ment Within Which to Work
Figure 6.4-2
Determination of Maximum Allowable Ambient
Limit Under PSD Increment
420
the maximum increments imposed are the same as
II values, except for the three-hour SOo
which is not to exceed 325 q/m (The Class
hour S09 increment is 512 g/m .)
the Class
increment limit
II three-
SOp var i ance
by Governor with FLM's concurrence.
In situations where the Class I increments are predicted
to be exceeded, and the source would exceed the relaxed
SO2 increments as described above, the applicant may
appeal to the Governor to receive a variance for sul fur
dioxide only. Particulate matter variances cannot be
obtained. In making this appeal, the applicant must
demonstrate that neither the 24-hour nor the 3-hour S0o
increment limits can be achieved. The
ment of 20 g/m must be met, however,
applicant must also demonstrate that
not adversely affect the air quality
annual S0? i ncre-
Additional ly the
the proj ect will
related values of
the area. The FLM, again, has input in this process and
is required to make a recommendation to the Governor who
can agree or disagree with the FLM recommendation. In
addition, a public hearing must be held. After consi-
dering the public input, the Governor, may grant a
variance. The EPA can then issue a permit, and the
source would then be permitted to exceed the SOo incre-
ments presented
per year .
in Table 6.4-4 for no more than 18 days
Variance by the Governor with the President's
cone urrence
If, in the above process, the FLM does not concur, the
permit can not be approved, unless the Governor over-
rides the FLM's veto. The Governor has the authoriza-
tion to override this veto and recommend a variance. In
such a situation, the recommendations of both the FLM
and the Governor are sent to the President. The Presi-
dent may approve the Governor's recommendation if he
finds the variance to be in the national interest. If
the variance is approved, the EPA may issue a permit,
and the source would then be permitted to exceed the SOo
increments presented in Table 6.4-4 for no more than 18
days per year.
The procedure discussed above is outlined
6.4-3.
in Fig ure
421
-W "°
-*
FLU'S
Concurrence
Must Be
Certified
and Sent
to State
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-3
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01
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EPA Cone
With FLM
commendat
to Deny,
mlt is De
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( a r
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<~ 01 fci
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£■
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422
Table 6.4-4
3
Maximum Allowable Increase ( gm/ )
Under Class I S0~ Variances
Peri od of Exposure
24-hour max i mum
3- hour maximum
Terrain Areas
Low
36
130
High
62
221
• Air Quality Related Values
The only "air quality related value" specifically cited
in the 1977 Amendments is visibility. Other values may
include fish and wildlife resources, vegetation, archae-
logic sites and soil impacts. The EPA has yet to pro-
vide general guidelines regarding the evaluation of
impacts of proposed emitting sources on "air quality
related values" and until such guidance is available,
determinations are to be made on a case- by -case basis.
The FLM reviewing the permit can recommend conditions
which would ensure protection of air quality related
values. For example, a condition that the facility
monitor the impacts of its emissions, and reduce their
level if adverse effects begin to occur may be
recommended .
FLM role in Redes i gnat ion of Area Classifications
A state may redesignate any area to Class I. States are
also permitted to redesignate certain areas to Class III except
the following areas greater than 10,000 acres in size: present
national monuments, primitive areas, recreation areas, wild and
scenic rivers, wildlife refuges, lakeshores, seashores, and
future national parks and wilderness areas. Redes i gnat i on of an
area to Class III is a complicated process requiring approval by
the governor, public notices and hearings, consultation with the
state legislature, and approval by a majority of potentially
affected local residents.
Detailed analyses are required prior to public hearing
including health, environmental, economic, social and energy
impacts of the proposal. Redes i gnat i on of areas within Indian
reservations may only be done by the applicable Indian governing
body.
The EPA Administrator may disapprove a proposed redesig-
nation only if the redes i gnat ion does not meet the procedural
requirements of Part C of the Act. If federal lands are included
in the proposed redes i gnat i on area, the FLM is to submit recom-
423
mendations on the proposal, but the state's decision, if it
differs, is binding. The EPA may be requested to resolve dis-
putes between states and Indian tribes on proposed redesigna-
tions. The redesi gnat i on process is summarized in Figure 6.4-4.
6.4.4
Visibility Protection
The 1977 Amendments added to the Clean Air Act a section
entitled "Visibility Protection for Federal Class I Areas". This
section declares as a National goal "the prevention of any fu-
ture, and the remedying of any existing, impairment of visibility
in mandatory Class I Federal areas" where impairment results from
man-made air pollution. The Amendments also required that by
February 1978, the Secretary of Interior, in consultation with
the states and the FLM's, are to identify any mandatory Class I
areas where visibility contributes significant values to the
area. These areas were published in the February 24, 1978 Feder-
al Register. As such, all Class I areas in California are areas
in which visibility is considered to be an "important" value. As
stated previously, the EPA was to have conducted a study on
visibilty (by Feb 1979), and promulgate regulations on visibility
by August , 1979.
These regulations, in essence, are to provide guidelines
to the states on the various techniques and methods to be used to
achieve the National goal for visibility. Such a goal would be
stated, in all probability, as a "visibility standard".
The regulations would identify "impaired visibility
areas" and would require each SIP in such areas to adopt emission
limits on sources of pollution, compliance schedules and other
measures necessary to achieve the visibility standard. These
measures will include what the Clean Air Act terms "Best Availa-
ble Retrofit Technology" (BART). Thus, SIPs must impose BART on
specific sources named in the Clean Air Act. These sources
consist of the sources in the 28 PSD categories, which have
potential (uncontrolled) emissions greater than 250 tons/yr of
any pollutant. In addition to these measures, the SIPs must
develop long-term strategies for achieving the visibility stan-
dard .
The EPA is allowed to exempt sources from BART; such
exemptions can be made if the EPA feels that such sources will
not contribute to visibility impairment. The EPA may not how-
ever, give this source-wide exemption to fossil-fuel fired power
plants greater than 750 MW. These units would be included in the
states' regulations and BART must apply. Exemptions for these
units may only be made on a case-by-case basis, where the owner
of such units demonstrates to the EPA that the unit of concern
would not contribute to impairment of visibility.
Any exemption that the EPA makes regarding these sources
and their inclusion in the SIP, must go through the FLM. The
Clean Air Act mandates that the FLM's concurrence must be ob-
424
Figure 6.4-4
Redes i gnat ion Procedure
Yes
Does Area To Be
Redesignated Contain Federal Land?
No
Written Notice by State or
Indian Governing Body to FLM
Allow Up to 60 Days for Con-
ferring or Submitting Written
Comments of FLM to State or
IGB*.
State (or IGB*) Must Prepare
Lists of Inconsistencies
Between FLM's Comment and the
State's (or IGB*) Recommenda-
tions for Redesignation, Plus
Reasons for Making the Redesig-
nation Against the Recommenda-
tion of the FLM.
Detailed Analysis of Reasons
for Redesignation, Including
Health, Environmental, Social
and Energy Impacts of Proposal ,
Should be Prepared 30 Days
Prior to Public Hearing.
Other States - IGB's and Federal
Land Mgrs. Whose Lands are
Affected by the Redesignation
Must be Notified 30 Days Prior
to Public Hearing
Submit Final Proposal to EPA, EPA
can Disapprove Only on Grounds of
Procedural Requirements, or Class
I Areas Specified on PSD Regula-
tions Which May Not be
Reclassified.
* Indian Governing Body
425
tained in order for any exemption of this type
(Section 169A(c)(3) of the Clean Air Act).
to be effective.
The Clean Air Act requires that a public hearing be held
on the proposed revision of any SIP relating to the E PA ' s visi-
bility requirements. The State is also required to consult with
the FLM on the proposed revision. Any recommendations and con-
clusions made by the FLM on this revision are required to be
included in the public notice announcing the hearing.
6.4.5
Ozone Protection
The 1977 Amendments also added a section on ozone pro-
tection to the Clean Air Act (Part B). The purpose of this
section is to provide for (1) better understanding of the effects
of human actions on the stratosphere; (2) better understanding of
the effects of changes in the stratosphere; (3) information on
progress made in regulating activities which may affect the ozone
in the stratosphere in such a way as to cause or contribute to
endangerment of the public health and welfare; and (4) informa-
tion on the need for additional legislation in this area.
The Act authorizes the EPA to conduct a study of the
effect of all substances, as well as practices and activities,
which may affect the stratosphere (particularly ozone). The EPA
may use any university or contractor to perform the studies
required by the Clean Air Act. In addition to the EPA study, the
Act mandates that further research and monitoring be done by the
following agencies:
1. National Oceanic and Atmospheric Administration
2. National Aeronautics and Space Administration
3. National Science Foundation
4. United States Department of Agriculture
5. United States Department of Health, Education and
Wei fare
Authorization is given to the
any substance which the EPA
EPA to write regulations to control
believes, based
their studies
on
would affect the stratosphere, particularly in the formation of
ozone. This would include chl orof 1 uorocarbon emissions from
aerosol cans and emissions from airplanes, cars, etc. These
regulations must take into account the feasibility and the costs
of achieving these controls. However, such regulations may
exempt medical use products for which the EPA. determi nes there is
no suitable substitute.
426
6. 5
STATE AND COUNTY REGULATIONS
6.5.1
State Ambient Air Quality Standards
California began setting Air Quality Standards in 1969
under the provisions of the Mulford-Carrell Act. With the pas-
sage of the Clean Air Act Amendments in 1970, the Federal Govern-
ment began adopting such standards for the entire country.
Wherever there is some variation between state and federal Air
Quality Standards, the most stringent or limiting standard
applies. Table 6.5-1 compares the Federal and California stan-
dards. It should be noted that the 1977 Amendments were recently
passed and may eventually have a significant effect on state
standards and county reg ul at i on s- part i c ul arl y in those regions
containing Class I areas.
6. 5. 2
County Regul at i ons
The Bureau of Land Managements Ukiah District (District
4) consists of 10 counties situated in four air basins. A list-
ing of the counties by basin is as follows:
North Coast Basin
Al 1 of Del Norte County
All of Humboldt County
All of Mendocino County
Part of Sonoma County
San Francisco Bay Area Basin
Part of Sonoma County
Al 1 of Napa County
Part of Sol ano Co unty
All of Marin County
Sacramento Valley Basin
Al 1 of Col usa Co unty
All of Yolo County
Part of Solano County
La ke County Air Basin
Al 1 of La ke County
The counties of the San Francisco Bay Area Basin al
the Bay Area Air Quality Management District (AQMD).
vidual county Air Pollution Control Districts in the
Air Basin have adopted common rules and regulations,
ties of Yolo and Solano have formed the Yolo-Solano
counties of Lake and Colusa are individual APCD's.
so com prise
The i n d i -
North
^ The
APCD.
Coast
cou n-
The
427
Table 6.5-1
Ambient Air Quality Standards
Aver aging Time
California Standard* National Standards2
Pollutant
Concentration
Method4 Primary3, $
Secondary 3- ■
Method7
O«i0»nt
(Ozone)
1 hour
0.10 ppm
1.200 ug/m3)
Ultraviolet | 240 ug/m3
Photometry |(o.l2 ppm)
Same as
Primary Std.
Chemiiuminescent
Method
Carbon Monoxide
12 hour
10 ppm
(1 1 mg/m3)
Non-Dispersive
Infrared
Spectroscopy
_
Same as
Primary
Standards
Non-Olspersive
Infrared
Spectroscopy
• hour
-
10 mg/m3
(9 ppm)
1 hour
40 ppm
(46 mg/m3)
40 mg/m3
(35 ppm)
Nitrogen Oiomds
Annual Average
-
Salt smart
Method
100 ug/m3
(0.05 ppm)
Same as
Primary
Standards
Proposed:
Modified j-m
Saltzman (escort.)
Chemiiuminescent
1 hour
0.2S ppm
(470 ug/m3)
—
Sulfur Otoxide
Annual Average
-
Conductimetrlc
Method
•0 ug/m3
(0.03 ppm)
-
24 hour
0.0S ppm
(131 ug/m3)9
365 ug/m3
(0.14 ppm)
-
Pararouniline
Method
3 hour
-
-
1300 ug/m3
(0.5 ppm)
1 hour
0.5 ppm
(1310 ug/m3)
-
-
Suspended
Particulate
Annual Geometric
Mean
60 ug/m3
High Volume
Sampling
75 ug/m3
60 ug/m3
Hign Volume
24 hour
100 ug/m3
260 ug/m3
150 ug/m3
Sampling
Sulfates
24 hour
25 ug/m3
AIHL Metnod
No. 61
-
-
-
La ad
30 Day
Average
1.5 ug/m3
AIHL Method
No. 54
1.5 ug/m3
-
High Volume
Sampling
Hydrogen Sulflda
1 hour
0.03 ppm
(42 ug/m3)
Cadmium
Hydroxide
Stracten
Method
-
-
-
Hydrocarbons
(Corrected for
Met nana)
3 hour
(6-9 a.m.)
-
-
160 ug/m3
(0.24 ppm)
Same as
Primary
Standards
Flame Ionization
Oetection Using
Gas Chromatography
ethylene
• hour
0.1 ppm
-
-
-
1 hour
0.5 ppm
Visibility
Reducing
"Articles
1 observation
In sufficient amount to (•)
reduce the prevailing visibility
to leu than 10 miles when the
relative humidity Is less than 70%
-
-
-
APPLICABLE ONLY IN THE LAKE TAHOE AIR BASIN:
Carbon Monoxide
• hour
6 ppm
(7 mg/m3)
NOIR
-
—
-
visibility
Reducing
Particles
1 observation
In sufficient amount to <•)
reduce the prevailing visibility
to less than 30 miles when the
relative humidity Is leu than 70%
-
-
-
428
Table 6.5-1 (Cont.)
NOTES:
California standards are values that are not to be
equaled or exceeded.
National standards, other than those based on annual
averages or annual geometric means, are not to be
exceeded more than once per year.
Concentration expressed first in units in which it was
promulgated. Equivalent units given in parentheses
are based upon a reference temperature of 25°C and
a reference pressure of 760 mm of mercury. All mea-
surements of air quality are to be corrected to a ref-
erence temperature of 25°C and a reference pressure
of 760 mm of Hg (1,013.2 millibar); ppm in this table
refers to ppm by volume, or micromoles of pollutant
per mole of gas.
Any equivalent procedure which can be shown to the
satisfaction of the Air Resources Board to give equi-
valent results at or near the level of the air quality
standard may be used.
National Primary Standards: The levels of air quality
necessary, with an adequate margin of safety, to
protect the public health. Each state must attain the
primary standards no later than three years after that
state's implementation plan is approved by the En-
vironmental Protection Agency (EPA).
National Secondary Standards: The levels of air
quality necessary to protect the public welfare from
any known or anticipated adverse effects of a pollutant.
Each state must attain the secondary standards within
a "reasonable time" after implementation plan is
approved by the EPA.
Reference method as described by the EPA. An "equi-
valent method" of measurement may be used but must
have a "consistent relationship to the reference method"
and must be approved by the EPA.
Prevailing visibility is defined as the greatest visibility
which is attained or surpassed around at least half of
the horizon circle, but not necessarily in continuous
sectors.
At locations where the state standards for oxidant
and/or suspended particulate matter are violated.
Federal standards apply elsewhere.
429
6.5.3
Perm it Rules
As mentioned previously, the intent of the Clean Air Act
in establishing procedures for permit rules is to require the
states to write and adopt such permit rules into their individual
SIPs. Until such time as these rules are approved by the EPA and
incorporated in the SIP, the EPA still remains the permitting
authority. Thus, in California, many Applicants who are required
to obtain a PSD permit from the EPA, are also required to obtain
a New Source Review permit from the County.
In nonatta i nment areas, however, no permits may be
issued until the SIP for these areas is approved by the EPA.
Thus, in California, no permits can be issued in these areas. At
the present time, many counties have rewritten their permit rules
to conform with a model or guideline rule which was drafted by
the CARB.
The permit rules have in the last year been rewritten by
the local districts to conform to the CARB Model Rule. Although
there are individual differences between the various districts'
rules regarding cut-off limits for review, control technology,
etc., the basic content of the rules follows the CARB Model Rule.
Thus a description of the provisions of the Model Rule will
suffice to describe the general district requirements.
At the present time, these rewritten
submitted to the CARB by the local districts.
process of reviewing these rules to see if they
Model Rule. After CARB reviews the local rule,
it, it then submits it to the EPA for review and
SIP. A local District may not submit directly
the State may submit individual rules to the EPA
the SIP. At this point, no rules have been submitted to the EPA;
they are presently either being adopted by the local District for
submission to the CARB, or have already been submitted to CARB
and are waiting for their review.
6.5.3.1 Description of Model Rule/Districts' Rules
rules have been
CARB is in the
conform with the
and cone ur s with
inclusion in the
to the EPA; only
for inclusion in
The CARB Model Rule was written to ensure compliance
with the requirements of the Clean Air Act, and to provide the
individual APCD's with guidance in writing their rules. By and
large, most of the Districts in California have adopted the rule,
with some minor changes between Districts. Thus, a description
of CARB's Model Rule will suffice to describe the indivudual
Districts' rules in California.
The Model Rule/District Rules currently apply in both
attainment and nonattai nment areas (A state PSD rule will even-
tually control sources in attainment areas). All sources, re-
gardless of emission levels, must first demonstrate compliance
with all District rules and regulations (emission limits, etc.).
It must also demonstrate that all company-owned sources in the
State are in compliance with all emission limitations and stan-
dards which are part of the SIP approved by the EPA.
430
If the emissions from the source are greater than 250
lbs/day (per the Model Rule; this may differ from District to
District), for any pollutant, BACT is required for all pollu-
tants .
If, after application of BACT, emissions of any pollu-
tant are greater than 250 lbs/day, the source must meet specific
requirements which differ according to two different scenarios as
i 1 1 ust rated bel ow :
t Sources Locating in Nonattainment Areas
Offsets must be obtained for pollutants, in ratios
greater than 1.2:1.
t Sources Locating in Areas which are Attainment or Show
Infrequent Violations
Offsets are required only as much as is needed to pre-
vent a new violation or to prevent the worsening of an
existing one.
6.5.3.2 California's Air Conservation Program (ACP)
In 1976, the CARB began writing a proposed guideline
permit rule affecting new or modified sources locating in attain-
ment areas of the State. It was the state's version of the EPA's
PSD program, and was called the California Air Conservation
Program (ACP). The CARB had drafted a rule incorporating a
four-level classification system of lands, as opposed to the
EPA's three-class increment system.
However, since the Clean Air Act Amendments of 1977
drastically changed the PSD requirements for states, and with the
rush of activity associated with nonattainment planning, the ACP
for the State was temporarily dropped.
Activity resumed recently on drafting the California
version of PSD. However, at this time, the rule is being written
to be equivalent to the EPA's present PSD regulations, and will
not contain extensive additions, or differences, as in the origi-
nal version. The CARB's purpose in their actions is to draft a
rule that the local Districts can easily adopt and which would be
easily approvable by the EPA. The rule would then be part of the
SIP, and could be enforced by the local Districts.
Subsequent to inclusion in the SIP, the CARB will then
commence work on a new version of the ACP which would eventually
replace their PSD regulation. Thus, their PSD regulation serves
only as an interim measure in order to obtain full State juris-
dictional authority to administer permit programs i n _attai nment
areas. The ACP will, in essence, be a more detailed PSD regula-
tion which is tailored to the air quality concerns and needs of
California. It is not known at this time whether the ACP will
include the utilization of the national Class I, II, and III
increment or another suitable increment standard.
131
The CARB wishes to have their interim PSD regulation
(Model Rule) drafted by October. They wish to have the Districts
adopt this regulation by the end of 1979.
6.5.3.3 Emission Regulations
The remainder of this section is categorized by the
pollutant causing event or by the pollutant. Each category is
followed by a discussion that describes either the typical regu-
lation as adopted by all or a vast majority of the APCD's, or the
regulations as adopted by an individual or group of APCD's. The
discussions are not intended to be all-inclusive; for more de-
tailed information and for special incidences, refer to the
county rules and regulations directly.
Visible Emissions
This regulation prohibits the discharge of air pollu-
tants for more than three minutes in any hour which is as dark or
darker than No. 1 or No. 2 on the Ringelmann Chart (as published
by the U.S. Bureau of Mines) depending on the APCD. Some APCDs
allowexceptions.
The Bay Area APCD and Mendocino County APCD use Ringel-
mann No. 1. The Lake County APCD, Yolo-Solano APCD, and all of
the APCDs in the North Coast Air Basin with the exception of
Mendocino County use Ringelmann No. 2. The following exceptions
general 1 y appl y :
1. Smoke from fires for prevention of a fire or health
hazard which cannot be abated by any other means.
2. Smoke from fires for instruction of public and
trial employees in methods of fighting fire.
i nd us-
3. Agricultural operations used in the growing of crops or
raising of fowl, animals, or bees.
4. The use of an orchard or citrus grove heater which does
not produce unconsumed solid carbonaceous matter at a
rate in excess of one (1) gram per minute.
5. Emissions which fail to meet the requirement solely
because of the presence of uncombined water.
The Ringelmann Chart is actually a series of charts,
numbered from 0 to 5, that simulate various smoke densities by
presenting different percentages of black. The charts are com-
monly referred to by number, thus a Ringelmann No. 1 is equiva-
lent to 20 percent black; a Ringelmann No. 5 is equivalent to 100
percent black. They are used for measuring the opacity of smoke
generated from stacks and other sources by matching with the
432
actual effluent the various numbers, or densities, indicated by
the charts. Persons can be trained and certified to use the
Ringelmann method using visual judgment without the use of the
charts .
Incinerator Burning
The burning of combustible refuse in any incinerator is
prohibited except in multiple-chamber incinerators or other
equipment found in advance by the Air Pollution Control Officer
to be equally effective for controlling air pollution. This rule
generally does not apply to incinerators used to burn only house-
hold rubbish and yard trimmings from single or two- family dwell-
ing on its premises. However, in some counties, burning in non-
approved equipment may be done only on "burn-days".
A multiple chamber incinerator is any article, machine,
equipment, contrivance, structure or part of a structure used to
dispose of combustible refused by burning, consisting of three or
more refactory lined combustion furnaces in series, physically
separated by refractory walls, interconnected by gas passage
ports or ducts and employing adequate design parameters necessary
for maximum combustion of the material to be burned.
Particulate Matter
These regulations limit the amount of particulate matter
that can be discharged from a source. A limit is also estab-
lished on the allowable rate of particulate emission based on
process weight. The rate varies for the APCDs.
Yolo and Solano County APCDs prohibit the discharge of
particulate matter in excess of 0.3 gr/SCF of exhaust volume as
calculated for standard conditions.
The Bay Area AQMD limits the weight of particulates in
an exhaust gas stream to 0.15 gr/SCF. For any incineration
operation or salvage operation capable of burning 100 tons of
waste per day, the limit is 0.05 gr/SCF. In addition, an allow-
able rate of emission is established based on a process weight
table contained in the regulations. Maximum emissions allowed
under this table are 40 lbs/hr.
Lake County limits combustion contaminants from sources
other than combustion sources to 0.2 gr/SCF or the emission limit
as established by the process weight table contained in the
regulations. Maximum emissions allowed under this table are 40
lbs/hr.
Combustion sources must meet the following p-articulate
matter limitations in Lake County:
1. 0.2 gr/SCF calculated at 12% C 0 2 for equipment in use
prior to December 20, 1971;
433
2. 0.1 gr/SCF of gas calculated at 12% COo for equipment
beginning operation after December 20, 1571.
The above particulate emission limits also apply to geothermal
operations although an exemption can be made during the air
drilling phase of the operation, during which time the particu-
late emission rate may reach a level of 100 lbs/hr for a time
period not to exceed 16 days.
The North Coast Air Basin has the following particulate
matter rules:
1.
2.
3.
4.
The discharge from any combustion source in excess of
0.2 gr/SCF (0.46 grams per standard cubic meter (g/SCM)
of exhaust gas), calculated at 12% of C02 is prohibited.
Steam generating units, installed or modified after July
1, 1976 may not discharge in excess of 0.1 gr/SCF (0.23
g/SCM) of exhaust gas calculated at 12% C02»
Kraft recovery furnaces may not discharge in excess of
0.1 gr/SCF of exhaust gas.
Non-combustion sources may not discharge in excess of
0.2 gr/SCF of exhaust gas.
The above emission limits are summarized in the table
bel ow
Table 6. 5-2
Limits for Particulate Matter
County/D i stri ct
Yolo/Solano APCD
Bay Area AQMD
Stack Gas
Concent rat i on
Limit
0.3 gr/SCF
(1) Incinerator operation 0.5 gr/SCF
or
Sal vage operat i on
(2 ) All other sources
Lake County
( 1 ) All sources other
than combust i on
sources
0.15 gr/SCF
0.2 gr/SCF
434
Emission
Limit
Process weight table
used to determine
al 1 owabl e emi ss i on
rate. Maximum limit
allowed is 40 lbs/hr.
Process weight table
used to determine
al 1 owabl e emi ss i on
rate. Maximum 1 imi t
allowed is 40 lbs/hr.
(2) Combustion sources
in use prior to
December 20, 1971
(3) Combustion sources
in use after
December 20, 1971
North Coast Air Basin
(1) Combustion sources
0.2 gr/SCF
0.1 gr/SCF
0.2 gr/SCF
0.1 gr/SCF
Process weight table
used to determine
al 1 owabl e emi ss i on
rate. Maximum limit
allowed is 40 Ibs/hr
Process wei ght table
used to determine
al 1 owabl e emi ssi on
rate . Max imum limit
allowed is 40 lbs/hr
Process wei g ht table
used to determine
al 1 owabl e em i ss i on
rate . Max i mum limit
allowed is 40 lbs/hr
Process weight table
used to determine
al 1 owabl e emi ssi on
rate . Max imum limit
alio wed is 40 lbs/hr
Process weight table
used to determine
al 1 owabl e emi ssi on
rate. Maximum limit
alio wed is 40 lbs/hr
Process we i ght table
used to determine
al 1 owabl e emi ssi on
rate . Max imum limit
alio wed is 40 lbs/hr
Sulfur Compounds
These regulations limit either the emission of sulfur
compounds at the point of discharge or the atmospheric concen-
tration of sulfur compounds.
In the Bay Area AQMD, sources of sulfur dioxide must
either meet a 300 ppm limit at the emission point or a much more
restrictive limit at ground level - 0.5 ppm for three consecutive
minutes or 0.5 ppm averaged over 60 minutes or 0.04 averaged over
24 hours. Further, the limits specified below are also- not to be
exceeded :
(2) Steam generating
units installed
or modified after
July 1, 1976
(3) Kraft recovery
furnaces
0.1 gr/SCF
(4 ) Non-combu st io n
so urces
0.2 gr/SCF
435
Tabl e 6.5-3
Bay Area AQMD
Maximum Allowable SCU Ground Level Limits
SCK Concent rat i on
ppm ( vol )
Averaging Time
(hrs)
1.5
0. 5
0.3
0. 1
0.04
0.05
1.0
3.2
9.6
24.0
The Bay Area AQMD has established the following limita-
tions for sulfur recovery plants, sulfuric acid plants and re-
finery equipment in refineries:
Table 6. 5-4
Bay Area AQMD
Emission Limitations for Sulfur Recovery Plants
and Refinery Equipment
Source
S 0 0 Limitation
Existing Controlled
PI ants
Existing Uncontrolled
PI ants
The more restrictive of 1500
ppm (vol) or 120 lbs per short
ton of sulfur products
By 1984, such plants must meet
the more restrictive of: 250
ppm (vol) or 4 lb per short
ton of sulfur produced.
3000 ppm (vol )
By 1981 the limit shall be:
The more restrictive of 250
ppm (vol) or 4 lbs per short
ton of sulfur produced.
New Sulfur Recovery Plants
The more restrictive
ppm ( vol ) or 4 lbs
sul fur prod uced .
of: 250
SOp/ton
436
Existing Sulfuric Acid
PI ants
Acid plants constructed
prior to 1955
Acid plants constructed
after 1955
Fluid Catalytic Cracking
Units, Fluid Co ker s
Coke Calcining Kilns
(vol ) or 250 lbs/hr.
6000 ppm through 1981
3000 ppm through 1981
By 1981 the limit shall be:
More restrictive of 300 ppm
( vol ) or 7 lbs S02/ton H2S04
produced
New Sulfuric Acid Plants
( vol ) or 4 lbs S02/ton H? S04
prod uct
More restrictive of 30 ppm
1000 ppm (vol )
More restrictive of 400 ppm
Lake County prohibits the discharge from any sulfur
recovery unit producing elemental sulfur of effluent process gas
containing more than: (1) 300 ppm by volume of sulfur compound
calculated as S0o, (2) 10 ppm by volume of hydrogen sulfide, and
(3) 100 pounds per hour of sulfur compounds calculated
d i ox ide .
as sulfur
For geothermal wells and power plants, Lake County has
recently adopted rules for the control of FUS emissions. FUS is
limited to 150 ppm from geothermal wells, unless there is an FUS
control system capable of achieving a 75% or greater reduction in
emissions. In all cases, the FU S emissions must be demonstrated
not to exceed the 1-hour ambient state standard for
H o S .
the
control
FUS
ambient monitor-
Exemptions to the 150 ppm limit and
system may be made if the developer installs an
i ng system in the downwind direction of the geothermal well, and
the ambient air standard for FUS is not exceeded. However, an
upper limit of 1000 ppm is imposed.
Geothermal power plans must
schedule of FUS emissions:
meet the following time
437
Table 6. 5-5
Emission Limits of H?S from
Geothermal Power Plants
in Lake County
Source
Emission Limit
Plants which have received
Authority to Construct (A/C)
prior to January 1, 1979
Plants receiving A/C on or
after January 1, 1979
Plants receiving A/C on or
after January 1, 1983
All plants by 1990
175 g/MW-hr until 1990
100 g/MW-hr until 1990
50 g/MW-hr until 1990
50 g/MW-hr
In Northern Sonoma County, the emission limitations for
H2S from geothermal power plants are the same as those listed
aDove for Lake County. However, geothermal wells are limited to
2. 5 kg H2S/hr.
The North Coast Air Basin has the following regulations
for emissions of total reduced sulfur (TRS):
1. Kraft recovery furnaces: (a) 10 ppm or 0.30 pounds of
TRS per ton of kraft pulp mill production as a monthly
arithmetic average, whichever is more restrictive; (b)
15 ppm of TRS as a daily arithmetic average; (c) 40 ppm
of TRS for more than 60 cumulative minutes in any one
day.
2. Lime kilns: shall not exceed 40 ppm of TRS or 0.20
pounds of TRS per ton of kraft pulp mill production as a
daily arithmetic average, whichever is more restrictive.
3. Other kraft mill sources: shall not exceed 20 ppm of
TRS or a cumulative value of 0.20 pounds of TRS per ton
of kraft pulp mill production as a daily arithmetic
average, whichever is more restrictive.
N i t rogen Ox i des
The Bay Area APCD limits nitrogen oxide emissions from
stationary sources. The limits are as follows:
1. Sources with heat input equal to or greater than 250
million Btu/hr. - 125 ppm when burning natural gas and
225 ppm when burning oil.
438
2 . Sources with heat input equal to or greater than 1,750
million Btu/hr. - 175 ppm when burning natural gas and
300 ppm when burning oil.
Area AQMD prohibits any source from emitting
. of lead per day resulting in a ground level
1.0 micrograms per cubic meter in excess of the
Lead Emissions
The Bay
more than 13 lbs
concentration of
bac kgro und 1 evel .
Odors
Two methods have been used by counties to regulate odors
in the atmosphere. In most counties, odors are covered under
regulations for nuisances (see separate section). The Bay Area
APCD Regulations call for district personnel to take a sample of
a suspected odor if ten citizen complaints are received within 90
days. The sample is then diluted with four parts of odor free
air. If it remains odorous after dilution, the source is in
violation of the regulation.
Nu i sances
This regulation generally prohibits any source from
emitting air contaminants or other material which cause injury,
detriment, nuisance or annoyance to any considerable number of
persons or to the public or which endanger the comfort, repose,
health or safety of any persons or the public or which cause or
have a tendency to cause injury or damage to business or prop-
erty. The working of this regulation varies with the overall
detail of the county or district regulations. In some cases,
nuisances such as odors are separated out and dealt with di-
rect! y .
Sulfur Content of Fuels
The Bay Area AQMD limits the sulfur in fuels
percent or the emissions from fuel burning to 300 ppm (as
Reduction of Animal Matter
to
SO
0.5
2).
This prohibits the reduction of animal matter in a
source unless all generated emissions are incinerated at temper-
atures of not less than 1200 degrees Fahrenheit for a period of
not less than 0.3 seconds or processed in a manner determined by
the Air Pollution Control Officer to be equally or more effective
for the purpose of air pollution control.
Miscellaneous Regulations
Other common regulations usually, but not always in-
cluded by counties and districts, include prohibitions on emis-
sions from organic solvents, new source performance standards,
439
emission standards for hazardous air pollutants, regulations on
organic liquid loading, regulations on loading gasoline into
stat i onary tanks .
6.5.3.4 Burning Regulations
The CARB has promulgated regulations governing the use
of open outdoor fires for agricultural operations and forest
management. Agricultural burning guidelines and meteorological
criteria for the regulation of agricultural burning were promul-
gated for each air basin on March 17, 1971. The purpose of the
regulation was to permit burning on days with good meteorology
based upon established meteorol og iccal criteria. Regulations
were adopted on March 17, 1971 and revised on June 21, 1972,
February 20, 1975, with a proposed revision April 27, 1978.
The regulations require that burning permits be obtained
prior to the use of open outdoor fires. These permits are to be
prepared by the designated agency and/or the appropriate APCD.
In most instances, the California Department of Forestry (CDF)
serves as the designated agency for burning in forested areas
throughout the state and, therefore, is responsible for the
issuance of permits.
While the CDF serves as the designated agency for the
issuance of burning permits in California, this responsibility
can be further delegated to other agencies. In some instances,
the BLM has been given authority by the CDF to issue permits for
land areas managed by the Department of Interior. These include
the Susanville and Bodie Planning Units. In these instances, BLM
area managers are directly responsible for the issuance of per-
mits and for coordination with other agencies. However, unless
this authority has been properly delegated, BLM area managers are
not responsible for permitting for open outdoor burning.
BLM area managers responsible for the administration of
Department of Interior lands in California must be cognizant of
the procedures necessary prior to any burning activities in these
areas. The principal points of contact for the BLM area managers
include the local APCD, the CARB, the National Weather Service
(NWS) and the CDF. The latter agency should serve as an initial
point of contact for area managers faced with the problem of
burning on federal lands for the first time. CDF personnel can
explain permit issuance procedures to BLM personnel and it is
good practice for BLM land managers to become very familiar with
this process. Table 6.5-6 provides a list of all CDF contacts
within California suitable for use by BLM land managers.
The requirements for a burning permit apply to all land
areas in the state with a few exceptions. Open burning for
agricultural operations in the growing of crops or the raising of
fowl or animals, as well as disease or pest prevention are exempt
from permitting requirements above an elevation of 3,000 feet
MSL. This exception does not apply in the Tahoe Air Basin. Land
440
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areas located at an elevation above 6,000 feet MSL, except in the
Tahoe Air Basin, are exempt from permitting requirements for all
agricultural burning which includes outdoor fires for agricul-
ture, pest control, forest management, range improvement, im-
provement of land for wildlife and game habitat, as well as in
the raising of fowl or animals. Most burning on BLM lands will
be for forest management or range improvement activity and there-
fore would be exempt to permitting requirements above 6,000 feet
MSL. Below this level, a permit will probably be required for
burning on BLM lands. Other special aspects of permitting re-
quirements include the permission to burn between the period of
January through May for range management, even on no-burn days if
50% of the land area has been chemically treated. In addition,
BLM land planners can notify the CARB seven days in advance for a
major burn at an altitude below 6,000 feet MSL. The agency will
then provide a special forecast 48-hours prior to the burn and
daily thereafter as a special service.
Once again, the CDF will serve as the designated agency
for permitting for most BLM lands in California. Other points of
contact for BLM land managers include the CARB for burn/no-burn
decisions for land areas at altitudes below 6,000 feet MSL. In
addition, close contact must also be maintainted with the NWS
relative to fire weather forecasts such that all burning can be
strictly controlled during dangerously dry periods. These are
the key contacts. It is important to proceed with an attitude of
cooperation with all agencies to insure safe outdoor burning as
well as to limit the possible impacts on ambient air quality by
the resultant smoke. BLM land managers will be required to keep
a record of the amount of acreage and the tonnage of material
burned daily as the APCD's will request this information in
preparing their required quarterly reports to the CARB regarding
burning permi ts .
Individual counties will prohibit such burning unless
the appropriate permit from CDF or other designated agency has
been obtained. In addition, the individual APCD's or county air
pollution control officer may designate a particular day as a
"burn day" or "no-burn day" dependent upon the meteorological
conditions within his jurisdiction and time of year. Persons
with the appropriate permits may commence their outdoor burning
subject to the conditions of their permits on days designated
"burn days". Individual county burning requirements are dis-
cussed bel ow .
Open Burning*
Prohibits the maintenance of an open fire (i.e., outdoor
burning unless specifically allowed by regulation. The language
of the regulation and the exceptions which apply vary by APCD.
* Including provisions for
range improvement burning.
agricultural, forest management and
442
On permissive burn days, the Yolo-Solano APCD exempt the
following fires:
1. A fire set or permitted by any public officer for the
purpose of preventing a health hazard which cannot be
abated by any other means, or for the instruction of
industrial employees in the method of fighting fires.
2. For right of way clearing by a public entity or utility,
or for levee, reservoir, and ditch maintenance when the
material has been prepared by stacking, drying, or other
methods to promote combustion as specified by the Air
Pollution Control Officer (APCO).
3. Agricultural burning permitted by law.
On all days this rule does not apply to the following
fires in the Yolo-Solano APCD:
1. A fire set or permitted by any public officer for the
instruction of a public or industrial employees in the
methods of fighting fire where a permit has been issued
by the APCO, or backfires necessary to save life or
v al uabl e property .
2. Fires for recreational use and cooking of foods.
3. To abate fires pursuant to Chapter 2 of Part 1 of Divi-
sion 12 of the California Health and Safety Code.
4. Fires not used for disposal of materials and which the
APCO determines necessary and not to have significant
air pollution effects.
5. Fires to burn empty sacks or containers which contain
pesticides or other toxic substances.
The Yolo-Solano APCD further prohibit the use of open outdoor
fires for the disposal of petroleum waste, demolition debris,
construction debris, tires or other rubber materials, materials
containing tar, or for metal salvage or burning of vehicle
bodies.
The Bay Area APCD allows the following exceptions to the
general prohibition of open fires.
1. Cooking and recreational fires.
2. Fires burning as safety flares or for the combustion of
waste gases .
443
3. The use of flame cultivation which uses LPG or natural
gas-fired burners designed and used to kill seedling
grass and weeds in orchards, vineyards and field crops
and the growth is such that the combusion will not
continue without the burner.
4. Any fire demonstrated to emit under all operating condi-
tions nothing but carbon dioxide, nitrogen oxides, or
water vapor.
5. Agricultural fires allowed by the County Agricultural
Commissioner for disease and pest prevention.
6. Fires allowed by public officials for prevention of fire
hazards including the disposal of dangerous materials.
7. Fires for the instruction of public and industrial
employees in fire fighting methods. (Each fire fighting
agency may set one fire for the purpose of training
volunteer fire fighters per quarter year on other than a
permissive burn-day if the APCO is notified at least two
weeks i n advance . )
8. Agricultural fires permitted by the proper officer
necessary to establish an agricultural crop in a loca-
tion which formerly contained another type of agricul-
tural crop or natural growth, during a period between
October 1 and April 30.
9. Agricultural fires permitted by the proper officer
necessary to maintain and continue the growing fruit and
nut trees, vineyards and cane fruits, as a gainful
occupation; and for the purpose of disposal of periodic
prunings and attrition losses from fruit and nut trees,
vineyards and cane fruits, during a period beginning
December 1 and ending April 30.
10. Agricultural fires permitted by the proper officer for
disposal of grain stubble from agricultural operations
on which both grain and vegetable crops are harvested
during the same calendar year and on which it is neces-
sary to remove the grain stubble and straw before plant-
ing a field vegetable crop, during a period beginning
June 1 and ending August 31.
11. Agricultural fires permitted by the proper officer
necessary to maintain and continue growing of field
crops as a gainful occupation and for the purpose of
disposal of stubble and straw, during a period beginning
September 1 and ending December 31.
12. Fires necessary to control the growth of vegetation in
irrigation ditches and canals.
444
13. Fires for preventing or eliminating a flood.
14. Fires certified by the Department of Fish and Game and
necessary for the improvement of lowland and marsh for
wildlife and game habitat, during a period beginning
February 1 and ending March 31, and a period beginning
October 1 and ending October 31.
15. Fires necessary to remove wood and vegetation debris
deposited by flood waters, for continuing or maintaining
agriculture as a gainful occupation during a period
between October 1 and May 31.
16. Range management fires permitted by the State Forester
necessary to maintain and continue the grazing of ani-
mals as a gainful occupation and for range improvement
and grazing, during a period between July 1 and April
30. Brush to be burned shall be treated at least six
months prior to burn if determined to be technically
feasible. Unwanted trees over six inches in diameter
are to be felled and dried for a minimum of six months.
17. Forest management fires to remove debris and for forest
management purposes during a period between November 1
and April 30.
All burning in the Bay Area APCD must be conducted only on per-
missive burn-days or with the permission of the APCO. Other
conditions are: (1) no material or fuel is to be ignited nor any
material or fuel added to any fire when the wind velocity is less
than 5 miles per hour, or when the wind direction at the site
causes the smoke to drift toward populated areas; (2) all piled
material is to be dried a minimum of 60 days prior to ignition or
demonstrated to contain less than 23 percent moisture on a dry
basis; (3) material to be burned is not to contain more than 5
percent native soil on a weight basis; and (4) piled material in
most cases is limited to a base area not to exceed 25 square
yards and the height is to be at least 2/3 of the average width
of the pile.
The North Coast Air Basin prohibits open fires for the
disposal of rubber petroleum or plastic wastes, demolition de-
bris, tires, tarpaper, wood waste, asphalt shingles, linoleum,
cloth, household garbage or burning of automobile bodies, except
for the fol 1 owi ng :
1.
2.
Cooking and recreational fires.
Fires for:
safety hazard
( b ) training
( c) backf i res
ty.
(a) the prevention of a fire, health or
which cannot be abated by any other means;
personnel in the methods of fire fighting;
necessary to save life or valuable proper-
,445
3. Fires used in the operation of a solid waste dump for
which a limited time extension has been granted by the
California Air Resources Board.
The following open outdoor fires are permitted in the
basin on permissive burn-days:
1. Agricultural operations for the growing of crops or
raising of fowl or animals.
2. Range improvement to remove unwanted vegetation or
establish an agricultural practice.
3. Forest management to remove forest debris.
4. Wildlife improvement to enhance wildlife or game habi-
tat .
5. Disposal of approved combustibles from single or two-
family dwellings on their premises. (Such burning is
exempt from permissive burn-day notification except in
the Humboldt Bay Air Basin and the Ukiah-Little Lake Air
Basin.)
6. Right-of-way clearing by a public entity or utility.
7. Ditch, levee and reservoir maintenance.
Lake County prohibits outdoor fires for the purpose of
disposal of burning of petroleum wastes, demolition debris,
fires, trees, wood waste, or other combustible or flammable solid
or liquid waste; or for metal salvage or burning of motor vehicle
bodies. Open fires may be conducted for the following purposes:
1. Prevention of a fire hazard which cannot be abated by
any other means on permissive burn-days.
2. The instruction of public and industrial employees in
methods of fighting fire.
3. Backfires necessary to save life or valuable property.
4. Disposal of solid waste from single or two -family dwell-
ings on its premises on burn-days.
5. Cooking and recreational fires.
6. Right-of-way clearing by a public entity or utility or
for levee, reservoir, and ditch maintenance on burn-
days .
7. For disposal of Russian thistle.
446
Agricultural burning, range improvement burning, and
forest management burning require a permit from the U.S. Forest
Service, the California Division of Forestry, or a County Fire
Protection District. Range improvement and forest management
burning may be conducted on no-burn days between January 1 to May
31.
The APCO in Lake County and the North Coast Air Basin
may authorize by permit open fires for the purpose of disposing
of agricultural wastes, or wood waste from trees, vines, bushes,
or other wood debris free of non-wood materials in a mechanized
burner such that no air contaminant is discharged into the atmos-
phere for a period of more than 30 minutes in any 8 hour period
which is as dark or darker than No. 1 on the Ringelmann Chart, as
published by the U.S. Bureau of Mines.
A permissive burn-day is any day on which a designated
person or agency (i.e., California Air Resources Board, APCD)
determines that certain specified burning is permitted. The
primary criteria for determining a burn-day are meteorological
conditions.
447
6.6
GLOSSARY OF TERMS
Air Pol 1 ut i on
Control District
Air Quality
Rel ated Val ues
Attainment Areas
Basel i ne
Concent ration
Best Avai 1 abl e
Control
Technology (BACT)
Best Ava i 1 abl e
Retrofit
Technology (BART)
Burn Day
CI ass
Designation
In California, the county regulatory body
responsible for the administration of air
pollution regulations.
Under the Prevention of Significant Deteriora-
tion Regulations for Class I areas, the effect
of potential pollutant emissions on such
variables of soils, vegetation and, most
importantly, visibility must be reviewed.
The term attainment area means for any air
pollutant an area which is shown by monitored
data or which is calculated by air quality
modeling to comply with any National Ambient
Air Quality Standard for such a pollutant.
The ambient concentration level reflecting
actual air quality as of August 7, 1977 minus
any contribution from major stationary sources
and major modifications on which construction
commenced on or after January 6, 1975.
An emission limitation (including a visible
emissions standard) based on the maximum
degree of reduction for each pollutant subject
to regulation under the Act which would be
emitted from any proposed major stationary
source or major modification which the Admin-
istrator, on a case by case basis, taking into
account energy, environmental and economic
impacts and other costs determined to be
achievable for such source or modification
through application of production processes or
available methods, systems and techniques
including fuel cleaning or treatment or inno-
vative fuel combustion techniques for control
of such pollutant. BACT must always be at
least as stringent as the Applicable New
Source Performance Standard.
Same as Best Available Control Technology with
specific application to existing sources.
A burn day is any day on which a designated
person or agency determines that certain
specified burning is allowed.
The designation of the country as either Class
I, II or III under the rules for the Preven-
tion of Significant Deterioration. Class I
areas reflect the most stringent requirements
while Class III areas are the most lenient.
"448'
CI ean
(CAA)
Air Act
CI ean Air Act
Amendment s
of 1977
The body of air quality legislation promul-
gated 1955 in with Amendments in 1963, 1965,
1967, 1970, and 1977, and codified in
42USC740/et seq., which are designed to regu-
late the nations air quality for the purpose
of protecting human health and welfare.
They represent the latest in a series of
expanding regulatory requirements designed to
protect the air quality resource in the United
States. The Amendments of 1977 ( PL 95-1 90 )
introduced key concepts including the Preven-
tion of Significant Deterioration, the use of
Best Available Control Technology and the
protection of ambient visibility levels.
Criteria
Pol 1 ut ants
Designated
Agency
Federal Land
Manager
That group of pollutants for which National
Ambient Air Quality Standards have been prom-
ulgated based upon an analysis of the effects
of such pollutants upon human health and
welfare. Currently, S02, NO , CO, HC , TSP,
lead and photochemical oxidaifts are criteria
pol 1 ut ant s .
The governmental agency with final authority
relative to air quality regulations.
Federal Land Manager means with respect to any
lands in the United States, the Secretary of
the Department with authority over such lands.
I ncrements
The maximum allowable increase in a specific
pollutant concentration over and above exis-
ting "baseline concentrations" as specified in
Section 163 of the CAA or as limited by the
difference between Air Quality Standards and
baseline concentrations for that pollutant.
I nd i an
Governing Body
Lowest Achievable
Emi ss i on Rate
(LAER)
The term means the governing body of any
tribe, band or group of Indians subject to the
jurisdiction of the United States and recog-
nized by the United States as possessing power
of self government .
The emission control technology applicable to
source located in a nonattainment area is
established based upon the term Lowest Achiev-
able Emission Rate. This term means that
level of emissions which reflects the most
stringent emission limitation that is con-
tained in the Implementation Plan of any state
or the most stringent emission limitation
which is achieved in practice on such class or
category of source which ever is more stringent.
449
Mandatory CI ass
I Area
Mod i f i cat i on
Nat i onal Ambi ent
Air Quality
Standards (NAAQS)
National
Emissions Stand-
ards for
Ha zardous Ai r
Pol 1 utants
(NESHAPS)
New Source
New Source
Performance
Standards (NSPS)
New Source
Review
The term means Federal areas which may not be
designated as other than Class I areas under
the Clean Air Act Amendments of 1977. These
areas are specified in Section 162(a) of the
Act .
Any physical change in the method of operation
or an addition to a stationary source, which
increases the potential emission rate of any
pollutant regulated under the Act by either
100 tons/year or more for any source category
identified by the New Source Performance
Standards or by 250 tons/year or more for any
stat i onary source .
The Clean Air Act Amendments of 1970 required
that specific pollutant concentration levels
be identified for the protection of human
health (i.e., Primary Standard) and welfare
(i.e., Secondary Standards) for each of the
criteria pollutants. These specific pollutant
levels comprise the National Ambient Air
Qual i ty Standa rds .
Standards promulgated for air pollutants for
which no ambient air quality standard is
applicable and which in the judgement of the
Administrator cause or contribute to air
pollution which may reasonably be anticipated
to result in an increase in mortality or an
increase in serious irreversible or incapaci-
tating reversible illness.
Any new structure, building, facility, equip-
ment, installation or opera i ton which is
located on one or more continuous or adjacent
properties and which is owned or operated by
the same person.
National Standards promulgated by the USEPA
which set emissions limitations for standards
of performance for each of 28 separate cate-
gories of stationary sources.
No major emitting facility on which construc-
tion is commenced after the date of the enact-
ment of the Clean Air Act Amendments of 1977
may be constructed in any area unless the
formal permit application process^ has been
completed in accordance with regulations
required by Section 165 of the Clean Air Act
Amendments of 1977.
450
No Burn Day
Nonattainment
Areas
A no burn day is any day on which a designated
person or agency determines that certain
specified burning is not permitted.
The term nonattainment area means, for any air
pollutant, an area which is showed by moni-
tored data or, which is calculated by air
quality modeling, to exceed any National
Ambient Air Quality Standard for such pollut-
ant .
Offsets
Soruces locating in nonattainment areas, must
obtain emission reductions form other existing
sources in the region that more than offset
the increase in emissions from the new source.
Such offsets must produce a positive net air
quality benefit resulting in reasonable fur-
ther progress toward attainment of the appli-
cable standard .
Perm it
Mora tori urn
Potential
Emissions
Pre-Construction
Review
The cessation of the air quality permitting
process pending the resolultion of mandatory
regulatory activity.
Potential Emissions refer to the maximum
emission of pollutants in the absence of air
pollutant control equipment.
No major emitting facility on which construc-
tion is commenced after the date of the enact-
ment of the Clean Air Act Amendments of 1977
may be constructed in any area unless the
formal permit application process has been
completed in accordance with regulations
required by Section 165 of the Clean Air Act
Amendments of 1977.
Prevent ion of
Si gn i f i cant
Deterioration
Pri mary
Standards
Reasonably
Available Control
Technology (RACT)
Specific requirements contained in the Clean
Air Act Amendments of 1977 (i.e. Part C,
Sections 160 through 169) designed to protect
the air quality resource in regions of the
country where present baseline pollutant
levels are below the National Ambient Air
Qual i ty Standard s .
Standards promulgated as part of the National
Ambient Air Quality Standards which set pollu-
tant levels which provide an adequate margin
of safety for public health.
The least stringent in the control technology
heirarchy applicable to existing sources which
require a level of control necessary to insure
compliance with existing emissions regula-
tions.
451
Retrofitting
Secondary
Standards
The installation of additional control tech-
nology on existing sources of air pollutants.
Standards promulgated as part of the National
Ambient Air Quality Standards which specify
levels which protect the human welfare from
known or anticipated adverse effects associ-
ated with a pollutants presence in the ambient
air.
State
Impl ementat i on
Plan (SIP)
The concept of State Implementation Plans was
introduced in the 1970 Clean Air Act Amend-
ments. There purpose is to insure that the
NAAQS are met in all areas of the country and
require a transportation control plan, emis-
sions limits for specific categories for
sources and permit rules for new or modified
sources of pollutants.
45;
BIBLIOGRAPHY
Bay Area Air Pollution Control District, Air Pollution and the
San Francisco Bay Area, Eleventh Edition , San Francisco,
California, June 1977, pp. 51.
Bay Area Air Pollution Control District, Regulation 1 (January,
1978; Regulation 2 (June, 1977); Regulation 3 (November,
1977); Regulation 5 (April 20, 1977); Regulation 7 (December,
1975); Regulation 8 (December 1976), San Francisco, Cali-
f orni a .
Lake County Air Pollution Control District, Rules and Regula-
tions, Lakeport, California, April 3, 1978.
North Coast Air Basin, Air Pollution Control Plan and Regulations
3 and 4, May 13, 1976, and October 15, 1977.
Yolo-Solano Air Pollution Control District, Rules and Regula-
tions, Woodland, California, September 28, 1977.
Ninety-Fifth Congress, "Clean Air Act Amendments of 1977" (Public
Law 95-95; 91 STAT. 685), August 7, 1977.
The Clean Air Act (42 U.S.C. 1857 et seq.)
Easton, E.B. and F.J. O'Donnel, "The Clear Air Act Amendments of
1977." Journal of Air PollutionControl Association, Vol.
27, No. 10, October 1977, p. 943-947.
Goldsmith, B.J. and R.J. Mahoney, "Implications of the 1977 Clean
Air Act Amendments for Stationary Sources", Environmental
Science and Technol ogy , Vol. 12, No. 2, Feb. 1976, p. 144-
149.
High, M.D. "Status Report on Federal Regulations For New Source
Performance Standards". Journal of Air Pollution Control
Association, Vol. 26, No. 5, May 1976, p. 471--479.
Stern, A.C. "Prevention of Significant Deterioration - A Criti-
cal Review", Journal of Air Pollution Control Association,
Vol. 27, No. 5, May 1977, p. 440-453.
453
7. 1
7. MONITORING RECOMMENDATIONS
GENERAL REQUIREMENTS
Possible alternatives for future land development of BLM
lands within the Ukiah District may require the preparation of
extensive environmental research reports and impact analyses. In
light of this fact, it is important to isolate areas currently
under BLM administration that lack substantial onsite data nec-
essary for the preparation of air quality and meteorological
analyses. Additionally, areas within the Ukiah District that
require enhancement of the current existing data base must be
identified so that transport and diffusion analyses can be accu-
rately performed.
The ultimate objective is to be able to define air
transport and dispersion characteristics and associated baseline
ambient air quality levels within the Ukiah District. An accu-
rate and current data base provides the means to achieve this
objective and enhances credibility of regional environmental
impact statements. It is of vital importance to all organiza-
tions concerned with future land development within the Ukiah
District, that the most accurate and complete environmental
impact statements be developed.
A review of the previous sections describing regional
air quality, dispersion meteorology and baseline climatology for
the Ukiah District indicates that certain areas lack the satis-
factory historical data base necessary to provide a definitive
characterization of these topical items which are essential in
environmental analyses. Climatological data are generally ade-
quate for all portions of the Ukiah District. Ambient air quali-
ty data are readily available for most areas of the district
where there exist substantial population centers. These cities
and communities are well distributed along the Pacific Coast.
Detailed dispersion meteorological data are available at a few
select locations throughout the district and represent the least
resolved data base of all the major air quality components. Data
are available to provide an assessment of regional dispersion for
most of the Ukiah District; however, the extent of the current
data base available for site- specific dispersion analyses on
lands under BLM administration is generally not satisfactory.
Lands within the Ukiah District currently under BLM
jurisdiction entail three basic geographical areas. As depicted
in Figure 7.1-1, a majority of the BLM lands in the Ukiah Dis-
trict are located in the mountainous areas. A small portion of
the BLM lands are located along the coast.
Alternative future land uses for these areas may include
construction or expansion of energy related facilities, other
commerical industrialization, recreation, agriculture, forestry
and many others. The development of BLM administered lands for
454
Coastal
Coastal Mountains-Northern Area
Coastal Mountains-Southern Area
Figure 7.1-1
Categories of BLM Lands in the Ukiah District
455
these alternatives may require extensive and elaborate environ-
mental impact assessments including air quality, dispersion
meteorology and climatology. The most accurate environmental
impact assessment is derived from a highly detailed site-specific
data base. Hence, the adequacy of the air quality data base for
specific areas of concern must be identified.
The Clean Air Act Amendments of 1977 required continuous
monitoring data after August 7, 1978 in support of permit appli-
cations for new major sources of air contaminants. The monitor-
ing is required for a period of one year unless (1) the analysis
could be accomplished sati sfactori 1y in a shorter period or (2)
available offsite data exists which satisfactorily describes
onsite conditions.
As discussed in Section 6, the need for monitoring in
support of Prevention of Significant Deterioration (PSD) permit
applications is based upon a potential to emit 100 tons or more
per year of any pollutant regulated under the Clean Air Act for
one of 28 major emitting facilities identified by the Act.
other classes of industry, monitoring requirements are based
potential emission rate of 250 tons per year. Monitoring is
required for TSP (total suspended particulates), S0?, CO, 0o
any
For
on a
then
and
the
NO
unless it can be established
emission requirement for
that a source will exceed
only one pollutant, then only that
pollutant need be monitored. Meteorological monitoring in sup-
port of the program must include (1) hourly average wind speed
and direction, (2) hourly averaged atmospheric stability, (3)
hourly surface temperature, and (4) hourly precipitation amounts.
Monitoring at multiple sites for both air quality and meteorology
is usually required in areas of rugged terrain. In most cases,
monitoring will be required for a period of one year. This may
be shortened, however, if the EPA agrees that worst case condi-
tions will be established during a reduced time period. In the
case that baseline conditions have been adequately established,
this monitoring requirement may be waived. Further guidance
relative to monitoring requirements is contained in the EPA
Guideline Series OAQPS No 1.2-096, "Ambient Monitoring Guidelines
for Prevention of Significant Deterioration (PSD)."
456
7.2
INSTRUMENTATION
This section provides a brief review of instrumentation
that is commonly used to monitor the various air quality and
meteorological parameters. A
the management and operation
provided .
summary of costs associated with
of monitoring programs is also
7.2.1
General Requirements
The purchase of an instrument
of two classes of requirements:
1. General Instrumentation
2. Specific Objectives
requires the consideration
There are many instrumentation requirements that will obviously
depend on the specific objectives of the study for which the
instrument is needed. There are, however, a number of instrument
requirements that should be considered before the purchase of any
instrument. The purpose of this section is to describe these
general requirements so that a buyer will be able to distinguish
between the instrumentation attributes that are important, and
those that are only "window dressing". The EPA may be contacted
for futher guidance on instrumentation and methods of procedure.
Re! i a b i 1 i t y
Reliability is possibly the most important criterion for
an instrument in continous use. Regardless of how accurately an
instrument is calibrated and read, it must be reliable to give
reproducible results.
Quality Control
Quality control are those activities performed to insure
that equipment is maintained and calibrated within specifica-
tions.
Quality Assurance
Quality assurance is the method which verifies that
quality control activities are performed, e.g., adherence to
schedule, documentation, double checks, etc.
Accuracy
Accuracy is defined as the closeness of the instrument
output reading to the true value of the parameter. The qualifi-
cations of an accurate instrument are as follows:
1. It is properly calibrated under known conditions
2. It has characteristics that are unchanging with time
457
3. The reactions of the instrument (dynamic response) to
changes in the measured parameter are known to within
the limits of error requirements.
Precision
Precision is generally defined as the degree of close-
ness of a series of readings of an unchanging parameter. There
often is confusion between the terms accuracy and precision. One
way of clarifying their meanings is through the use of the "bulls
eye" analogy. Figure 7.2-1 depicts this analogy.
Sens i t i v i ty
Sensitivity is defined as the smallest change in the
measured variable that causes a detectable change in the output
of the instrument.
Simp! i c i ty
The lack of instrumentation experience among most obser-
vers makes this attribute a must for most meteorological and air
quality instrumentation. The qualifications of a simple instru-
ment are as f ol 1 ows :
1.
Operational
simpl e
adjustments of the instrument should be
2.
A simply written Standard Operating Procedures (SOP)
manual should accompany the instrument
Adjustments that are not
purchaser should require a
intended to be
special tool.
made by the
Durabi 1 i ty
Obviously, an instrument should be durable enough to
survive vibrations and shock encountered in transportation, rough
handling, etc. A meteorological or air quality instrument, in
addition, should be able to perform reliably in all seasons of
the year , and in a smoggy and corrosive atmosphere.
Conveni ence
Convenience of operation is definitely a must for an
operational instrument. As a general rule, an instrument that is
simple to operate is also convenient to operate.
Other requirements such as
ratio, etc. are objective oriented,
1 ater sect i on .
time constants, damping
and will be covered in a
458
Neither accurate
nor precise
Accurate but
not precise
Precise but
not accurate
BOTH accurate
and precise
Figure 7.2-1
The Relationship Between
Instrument Accuracy and Precision
459
7.2.2
Meteorological Instruments
Measurement of atmospheric variables that affect the
diffusion and transport of air pollutants is a necessity in
nearly every air pollution investigation. Suitable measurements
may be available from existing instrumentation at Weather Service
city offices, airport stations, or from universities or indus-
tries with meteorological installations. Frequently, however,
existing instrumentation does not give detailed enough measure-
ments, is not representative of the area in question, or does not
measure the variables desired (such as turbulence) and additional
instruments must be operated.
Of primary importance in air pollution meteorology is
the measurement of wind, including both velocity (direction and
speed) and the turbulence. The stability of the lower layers of
the atmosphere in which the pollution diffuses is important and
may be determined from an analysis of the turbulence character-
istics of the atmosphere or the temperature lapse rate.
Of secondary importance is the measurement of humidity
(which may affect atmospheric reactions), temperature, precipi-
tation (of importance in washout of pollutants), and solar radi-
ation (which affects photochemical reactions in the atmosphere).
Particularly for research studies, it may also be desirable to
measure meteorological elements affected by pollutants, such as
visibility, solar radiation, and illumination (radiation in the
visible range).
Wind Measurements
Surface Instrumentation
t Wind Speed
Generally, wind speed sensors are broken down into the
following categories:
a. Rotational Anemometers
1) Vertical Shaft
2) Horizontal Shaft
b. Pressure Anemometers
1) Flat Plate Type Anemometer
2) Tube Type Anemometer
c. Bridled Cup Anemometer
d. Special Types
1) Hot Wire Anemometer
2 ) Sonic Anemometer
3 ) B i v a n e
4) Vert i cal /Hori zontal (UVW) Anemometer
460
Pressure anemometers, hot wire and sonic anemometers
have enjoyed extensive use in research type operations, but they
all have disadvantages which have prohibited their use in opera-
tional type situations, such as air pollution surveys. The
rotational type anemometers are the most common type of wind
speed sensor in use today mainly because they are the only types
that satisfy all of the following desirable operational features:
a. Essentially linear relationship between the sensor
output and the wind speed;
b. Calibration unaffected by changes in atmospheric temper-
ature, pressure or humidity;
c. Able to measure a wide range of wind speeds (<2 to 200
mph [.9 to 90 m/s]) .
d. Long term calibration stability, or calibrations that
remain unchanged after 10 years continuous operation;
e. Output of the sensor easily adapted to remote indi-
cation;
f. Recording of the wind speed data easily adaptable to
either analog or digital form; and
g. Generally an extremely small maintenance requirement.
Figure 7.2-2 provides a visual review of routinely
available anemometers.
• Wind Direction
Wind direction sensors are visually presented in Figure
7.2-3 (a-p). They include; (1) flat plate vanes (a, b,
c, d, g, i, k, 1), (2) splayed vanes (e, f, h, p) and
(3) aerodynamic shaped vanes (j, m, n, o) .
The splayed vane of Figure 7.2-3 has, mainly because of
its durability and reliability, found widespread use in
its role as the main wind
National Weather Service. It
direction data obtained from
vice should be used only as
wind direction.
direction sensor for the
should be noted that wind
the National Weather Ser-
an indication of average
A bi-directional vane is designed to rotate around a
vertical axis to measure the azimuth angle of the wind,
as does a conventional wind vane. It also can move in
the vertical to measure the elevation angle of the wind.
Because the vertical motions of the atmos-phere are
frequently of a different character than the horizontal
motions (anisotropic turbulence), measurement of both
the horizontal and vertical motions are desirable. This
is particularly true under stable conditions when the
461
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|s^#i
ft •— 4
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JT . JN;X- ,,j
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J^^^^^^j^^^
pi—a.nw -
Climet Inst. Co. (a)
R.M. Young Co. (b]
Belfort Inst. Co. (c!
Henry J. Green Co. (d) Electric Speed Indicator Co. (e) Science Associates Inc. (f)
Teledyne-Geotech (Bkmn & Whtly) (g)
Teledyne-Geotech (Bkmn & Whtly) (h)
Figure 7.2-2
Cup Anemometers
462
Climet Inst. Co. (a)
R.H. Young Co. (b)
Belfort Inst. Co. (c)
t ! A
Science Associates Inc. (g) Epic Co. (h)
Epic Co. (i)
e
Bendix Co. (m)
Belfort Inst. Co. (n)
Teledyne-Geotech (1)
Figure 7.2-3
Wind Vanes
463
L
Wong Lab. (d)
Electric Speed Indicator Co. (e) Science Associates Inc. (f)
S'
&
(1
Teledyne-Geotech (j)
Teledyne-Geotech (k)
■ . ». £2&i B i
Raim Inst. Co. (o)
■«»».» r ■^.•~- r *»
rVi«rfrni«i ufcww iHtUi' i ij>»
Epic Co. (p)
Figure 7.2-3 (Cont.)
Wind Vanes
464
vertical motion is almost absent, but horizontal changes
in wind direction may be appreciable. Micro-potentio-
meters are usually used to produce an analog record of
both angles. The total wind speed can be measured by
replacing the counterweight with a propeller anemometer.
Figure 7.2-4 shows two typical anemometer bivanes.
Wind Measurements - Airborne (Winds Aloft)
Fixed location wind velocity sensors measure the wind at
a fixed height as it varies with time. Most airborne sensors are
used to average wind velocity through a given depth of the atmos-
phere at a particular time.
• Pilot Balloon (pibal)
This method of measuring wind velocity uses a gas-filled
free balloon (Figure 7.2-5) which is tracked visually
through a theodolite. The theodolite is an optical
system used to measure the azimuth and elevation angle
of the bal 1 oon .
a. Single Theodolite Pibal s
When only one theodolite is used, the balloon is
inflated to have a given amount of free lift. The
elevation and azimuth angles are used with the
assumed ascent rate to compute wind directions and
speeds aloft. A theodolite is shown in Figure
7.2-6.
b.
Double Theodolite Pibals
By this method, the ascent rate of the balloon is
not assumed, but calculated from the elevation and
azimuth angles of the two theodolite observations
taken simultaneously. The two theodolites are set
a known distance apart (the baseline). Two types
of pilot balloons frequently used reach 3000 ft.
within 5 minutes and 8 minutes, respectively, after
release. If detailed structure of winds with
height is to be determined, readings of azimuth and
elevation angle must be read every 15 or 30 sec-
onds .
Rawi nsonde
This method of measuring wind velocity aloft also uses a
gas-filled free balloon, but it is tracked either by
radio direction finding apparatus, or by radar. The
former method is that most frequently used in the U.S.
The radio transmitter carried by the free balloon is
usually used to transmit pressure, temperature and
humidity information to the ground (radiosonde). The
465
" 'ii iii ram a.
Figure 7,2-4 Anemometer Bi vanes
Figure 7.2-5 Meteorological Balloons (L to
R - Tetroon, Pilot Balloon,
Kytoon)
Figure 7.2-6 Theodolite
466
radio direction finding equipment determines the eleva-
tion angles and azimuth angles of the transmitter. The
height is determined by evaluation of the temperature
pressure sounding. Using radar, the slant range is
available for determining height. Soundings taken with
this type of equipment are made on a routine basis for
supporting forecasting and aviation activities. The
ascent rate of these balloons is on the order of 1000
feet/minute, so they do not yield as much detailed
information on winds in the lowest part of the atmos-
phere as is desired for many air pollution meteorolo-
gical purposes.
• Rocket Smoke Plumes
A system using a cold propellant, recoverable rocket to
emit a vertical smoke trail to an altitude of 1200 feet
has been developed. This smoke trail is photographed
simultaneously at short time intervals by two cameras
2000 feet from the launch site, at right angles to each
other. The difference in position of the smoke trail
from two successive photographs is a measure of one
component (north-south for example) of the wind and can
be determined at any number of heights from ground level
to 1200 feet. Another similar system has been reported
by Cooke (1962).
• Constant Level Balloons
Unlike the previous airborne sensors for wind velocity
which obtain average measurements through a vertical
layer, constant level balloons are used to determine the
trajectory or path of an air parcel during a given time
interval. In order to maintain a constant altitude
(more accurately to fly along a constant air density
surface) the balloon must maintain a constant volume. A
tetrahedron shaped balloon (tetroon) of mylar has been
used for this purpose (Figure 7.2-5). These have been
tracked visually and by radar (Angell and Pack, 1960).
Temperature Lapse Rate
The vertical structure of temperature gives an indica-
tion of the stability and turbulence of the atmosphere.
• Temperature Difference Measurements
One method of estimating the vertical structure of
temperature is by measuring the difference in tempera-
ture between sensors mounted at different heights.
This, of course, gives an average condition between any
two particular sensors.
467
Balloon-borne Sensors
Temperature sensors may be lifted by either free or
captive balloons. By these methods, temperature, not
temperature difference, is measured.
1.
Radiosonde
The method of radiosonde ( rad i o- sound i ng s ) observa-
tions is used routinely for temperature, pressure
and humidity soundings of the upper air. A free
balloon carries the sensors and a radio transmitter
aloft. Cycling from sensor to sensor is accom-
plished by means of an aneroid barometer, and
consequently, is a function of pressure. Observa-
tions are normally made twice daily at 0000 GMT and
1200 GMT at approximately 70 stations in the con-
tiguous U.S. The ascent rate of the balloon is
about 1000 ft/minute. Generally only 4 to 6 temp-
erature readings are recorded within the lower 3000
feet, so the vertical temperature information is
not too detailed, but it is still of considerable
use when more detailed information is not avail-
able.
T-Sonde
This system consists of a temperature sensor and
radio transmitter which is carried aloft by a free
rising balloon. The main difference between this
system and the radiosonde system is that only
temperature is measured. Ten to twelve measure-
ments are taken within the lower 3000 feet of the
atmosphere, thus giving a more detailed structure
of temperature with height.
Tethered Kite Balloon
Using a captive balloon system to make vertical
temperature measurements has the advantages of both
a complete recovery of all components of the sys-
tem, and as detailed a temperature sounding as is
be made by controlling the level of the
balloon having fins is much easier to
gives greater lift in slight winds than
balloon (see Figure 7.2-5). Most kite
be used in winds less than 15 knots
des i red may
sensor. A
control and
a spheri cal
bal 1 oons can
and for air pollution meteorology purposes, these
light wind periods are of greatest interest.
Because of hazards to aircraft, prior permission
from the FAA is required for flights exceeding 500
feet above ground and several methods of relaying
the observation to the ground have been used.
468
• Aircraft Borne Sensors
In some cases, light aircraft or helicopters have been
used for obtaining temperature lapse rate measurements.
Although there are complete systems commercially avail-
able for this metod of temperature lapse rate measure-
ment, one can use standard temperature sensors (therm-
isters, resistence thermometers, etc.) and recorders, as
long as exposure guidelines are followed.
Precipitation
Because large particles and water soluble gases may be
removed from the atmosphere by falling precipitation, measure-
ments of this element may be needed. Chemical or radioactive
analysis of rainwater may also be desired.
• Standard Rain Gauge
The standard rain gauge consists of a metal funnel 8
inches in diameter, a measuring tube having 1/10 the
cross- sect i onal area of the funnel, and a large con-
tainer 8 inches in diameter (Figure 7.2-7). Normally,
precipitation is tunneled into the measuring tube and
the depth of water in the tube is measured using a dip
stick having a special scale (because of the reduction
in area). Measurements with this instrument, because
they are made manually, yield only accumulated amount
since the last measurement.
H umi d i ty
Because of its influence upon certain chemical reactions
in the atmosphere and its influence upon visibility, it may be
desirable to measure humidity in connection with an air pollution
investigation. Also, some air pollutants affect receptors dif-
ferently with different humidities, so measurement may be im-
portant in this respect.
• Hy grot hermograph
This instrument measures both temperature and humidity
by activating pen arms to give a continuous record of
each element on a strip chart. The chart generally can
be used for 7 days. The humidity sensor generally uses
human hairs which lengthen as relative humidity in-
creases and shorten with humidity decreases. Tempera-
ture measurements are usually made with a bourdon tube
which is a curved metal tube containing an organic
liquid. The system changes curvature with .changes in
temperature, activating the pen arm. A hygrot hermograph
is shown in Figure 7.2-8.
469
Figure 7.2-9
"Black and White" Pvranometer
470
• Psychrometers
Humidity measurement by a psychrometer involves obtain-
ing a dry bulb temperature and a wet bulb temperature
from a matched set of thermometers. One thermometer
bulb (wet bulb) is covered with a muslin wick moistened
with distilled water. There must be enough air motion
to cause cooling of the wet bulb due to evaporation of
the water on the wick. To obtain this a motor driven
fan may be used to draw air at a steady rate past the
moistened wick while a reading is taken. A sling psy-
chrometer has both thermometers mounted on a frame which
is whirled through the air to cause cooling by evapora-
tion. Relative humidity is then determined from the dry
and wet bulb readings through the use of tables. Con-
tinuous measurements of humidity, however, can not be
obtained using psychrometers.
Radiation
The influence of the sun's radiation upon the turbulence
of the atmosphere and upon certain photochemical reactions is
sufficient to make measurements of radiation quite important. In
addition, radiation may be reduced due to particulate pollution
in the atmosphere. Particularly for research purposes, it may be
desirable to measure this effect by comparisons between urban and
non-urban stations with similar instruments.
0 Total Radiation
The direct radiation from the sun plus the diffuse
radiation from the sky may be measured by pyranometers.
These instruments are mounted so that the sensor is
horizontal and can receive the radiation throughout the
hemisphere defined by the horizon. The instrument
illustrated in Figure 7.2-9 is of this type.
• Direct Solar Radiation
The direct solar radiation may be measured continuously
by using the pyrhel i ometer shown in Figure 7.2-10 moun-
ted upon an equatorial mount (Figure 7.2-11) to keep it
pointed toward the sun. By using filters, different
spectral regions of radiation may be determined.
• Net Radiation
The difference between the total incoming (solar plus
sky) radiation and the outgoing terrestial radiation may
be useful in determining the stability, and -nence, the
turbulent character of the lowest portion of the atmos-
phere. A net radiometer serves this purpose and is
shown in Figure 7.2-12.
471
L
Figure 7.2-12
Net Radiometer
Figure 7.2-13
Transmissometer Detector
/il A v
II
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■■-■•.' ','- "•. ♦ :.:•»• ".:. ■-■ ■
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.-., ±,4 # ; , ,~,|->; ^j- '•"-,>.•;/.< !~, .
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;: ;j:\. v -r.f.--.-._ 5 .<- -. :* ...*■. •
Figure 7.2-14
Transmissometer Receiver
i
Figure 7.2-15
Integrating Nephelometer
472
Visibility
Visibility, in addition to being affected by precipita-
tion, is affected by humidity and air pollution. Frequently,
visibility is estimated by a human observer. An instrument to
measure visibility, called a transmissometer, measures the trans-
mission of light over a fixed baseline, usually on the order of
500 to 700 feet. An intense light source from the projector is
focused on a photocell in the detector,
reaching the photocell over the constant
assumed to be proportional to visibility,
restricted to estimating visibility in one
The amount of light
baseline distance is
The transmissometer is
direction only.
A transmissometer is also limited in that the light
transmission it detects is affected mainly by liquid droplets in
the air. It does not detect, to any great efficiency, the par-
ticulate matter in the atmosphere. The projector is shown in
Figure 7.2-13 and the detector in Figure 7.2-14. A relatively
new instrument, called a nephel ometer , has been developed which
measures the amount of light scattered by impurities, (mainly
dust) and thus indicates visibility as it is affected by particu-
late matter in the atmosphere. It provides for continuous out-
put, operating day or night, rain or shine and is relatively easy
to calibrate. It is limited, however, in that measurements may
be taken only at the instrument location. An integrating nephel-
ometer is shown in Figure 7.2-15.
Another instrument used to determine visibility is the
Vista Ranger (telephot ometer), which provides radiance values of
a target and the sky, contrast transmittance and data regarding
target chromat i ci ty . In other words, it is a telescope type
instrument which looks at the sky and a target (such as a moun-
tain peak) and measures the brightness contrast between the two
and transmits information on the true color of what is seen.
Measurements can be made over long path lengths (tens of Km) and
provide quantitative and continuous output. The Vista Ranger,
however, can be used only during daytime and readings are more
accurate during times of higher sun angle and relatively clear
skies.
7.2.3
Air Quality Instruments
The following paragraphs discuss sampling techniques for
NO
CO, 0
the measurement of the criteria pollutants TSP, SOo
and non-methane (unreactive) hydrocarbons (NMHC). Sampling for
more sophisticated pollutant species (e.g., sulfates, organic
compounds, etc.) is beyond the realm of the discussion and refer-
ence is made to the bibliography for a more detailed discussion.
7.2.3.1Particulates
Particulate pollutants are divided generally into dust
that settles in air and dust that remains suspended as an aero-
sol. The physical consideration determining the class into which
a particle falls is the particle diameter.
473
As a matter of working definition, particles larger than
10 inch diameter are usually thought of as "settleable" while
those of a smaller diameter are referred to as "suspended".
Instruments designed to collect either class of partic-
ulates are ordinarily chemically passive physical collectors
whose function is merely to permit measurement of the collected
material without regard to the composition. Generally, the
particulates encountered include various mineral dusts (i.e.
metallic oxides, sand, carbon particles, flyash fibers and pol-
len). These particulates can be collected using equipment based
on one or more of the following principles.
Dust Sampling by Gravity Settling (Dustfall)
Particles generally larger than 10 in diameter, which
are known to settle from air and collect on horizontal surfaces,
can be sampled merely by placing an open container in an outdoor
area that is free from overhead obstructions. These collectors
are ordinarily constructed of polyethylene, glass, or stainless
steel, since the inside walls must be inert to atmospheric oxi-
dative flaking, which would contribute to sample weight. In
addition, identical dustfall containers should be employed in the
same sampling network or where a comparison of results will be
made. Figure 7.2-16 presents a simple dustfall collector.
In sampling rather large areas, such as entire communi-
ties, it is common to employ at least one dustfall container for
every 10 square miles. On the other hand, when dustfall sampling
is intended to measure the effect of a given industry or indus-
trial complex, containers may be placed as close as a few hundred
feet apart .
atmo
Ther
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Mg
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meas
ul at
eval
eros
emi s
depo
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This basic working principal is
spheric deposition station located
e are 40 to 60 sinrUar
owing elements:
, and pH
stations ? nationwide
N03", P04'\ CO, NH4,
including total and free acidity and
SO
the foundation for the
in the Ukiah District.
rn^e a s u r+i n g | h_ e
K , Na , Ca ,
al kal i ni ty and
trical conductivity. The objectives of this program are to
ure atmospheric deposition, through precipitation and partic-
e settling, identifying spatial and temporal trends, to
uate the importance of natural
ion, etc.) and human activities
sions, etc.) as they contribute
sition and finally, to research
have on activities such as
eries and wildlife management.
phenomena (volcanos, soil
(power plants, industrial
to the total atmospheric
the effect these elements
agricultural, forest, range,
Dust Sampling by High-Volume Filtration (The High Volume Sampler)
The high-volume (hi-vol) sampler (see Figure 7.2-17)
employs the sloping roof of the shelter as a means for causing
air entering the sampler under the eaves of the roof to change
474
Figure 7.2-16
Simple Dustfall Collector
475
Figure 7.2-17
High Volume (hi-vol) Air Sampler
476
direction at least 90 before entering the horizontal filter.
Particles that remain entrained in the air sample prior to hori-
zontal filtration have, in so doing, satisfied the definition of
truly suspended dust or dust that is not subject to settling
under the influence of gravitational force.
The hi -vol is a vacuum cleaner- type motor that is used
to draw sample air through a filter area. The filter most fre-
quently employed is the 8 X 10 inch mat, which allows collection
of an air sample at a rate from 40 to 60 cubic feet per minute
(cfm) over a normal sampling period of 2 4 hours. Ihese condi-
tions permit the sampling of from 58,000 to 86,000 ft of ambient
air, with consequent extraction of about 1/2 gram of suspended
particulate (aerosol). This provides quite a substantial weight
of sample, which greatly simplifies subsequent chemical or physi-
cal analysis.
The motor is usually started and stopped by a simple
clock timer, and the duration of sampling is measured by an
elapsed time meter that is placed in series with the Hi -Vol
motor. Starting and finishing times are at the discretion of the
operator, although the EPA recommends starting and finishing from
midnight to midnight--24 hours every sixth day. The National Air
Sampling Network operates such samplers over the entire country.
On the other hand, short-term studies to determine day-to-day
variation in particulate levels may require continuous daily 24-
hour sampling.
7.2.3.2 Continuous Gas Analyzers
In general, these instruments are based on one of the
following principles of operation: color i met ry, atomic or mo-
lecular absorption, chemi 1 umi nescence , conductivity, coulometry,
or c omb u st i on .
In the past, colorimetric instructions have been used
with varying degrees of success to monitor air by
sical col or- form i ng reactions to such plumbing and
were required to produce continuous recorded data,
ly, however, the realm of solid-state physics has
sensing equipment that respond to physical rather
properties at even the lowest levels of gaseous air
adapting cl a s-
electronics as
More recent-
produced gas-
t han chemi ca 1
contaminants .
Therefore, emphasis is placed on the more recent physi-
cal instrumentation for the individual air contaminants. Future
development in continuous air monitoring systems will probably be
along the lines of physics rather than solution or chemical
meas urement .
Carbon Monoxide ^
Automated continuous methods for CO include applications
of gas chromatography, nondispersive infrared absorption, cataly-
tic oxidation, and displacement of Hg from HgO to produce mercury
vapor .
477
The most commonly used instruments for CO measurement
are those which use the principle of nondi s pers i ve infrared,
employing either a long path (40 in) or, more recently, a 10 cm
(0.39 in) path of infrared radiation.
These analyzers depend on the characteristic energy of
absorption of the CO molecule at not only its absorption wave-
length maximum of 4.6 but also at a number of equally specific
lines ranging from 2 to 15 , which together differentiate CO
from such interferences as C09, H90, S09 and NO
2*
As shown in Figure 7.2-18, these instruments employ a
heated filament as the source of radiation, a chopper to alter-
nate radiation between the sample and reference cells, a sample
cell (usually copper or brass), a reference cell of the same
material, and a detector.
Sulfur Dioxide ( S 0 2 )
Among the earliest applications of continuous analyzers
to ambient air monitoring were those involving measurement of
SO2. Both continuous and intermittent (sequential) sampling
methods have been employed. These often made use of the colori-
metric method of West and Gaeke. The West-Gaeke method was first
adopted as the approved reference method by the National Air
Pollution Control Association (NAPCA, 1969), before being re-
placed by the EPA colorimetric method.
For the past several years, the monitoring of sources
such as kraft paper mills and oil refineries, whose emissions
require a continuous total sulfur analyzer, has been accomplished
by means of a total combi ned- sul f ur flame photometer.
In this analyzer, sample air is admitted into a hydro-
gen-rich air flame. Specificity to sulfur arises from the use of
a narrowband interference filter that shields the photomul t i pi i er
tube detector from all but the 394 m emission energy of flame-
excited sulfur atoms.
Nitrogen Dioxide ( N 0 9 )
Traditionally, continuous analyzers for NO2 have em-
ployed the Gri es s-Sal t zman modified colorimetric method. Recent-
ly, several continuous NOo-measur i ng instruments operating on the
principle of chemi 1 urn i nescence have been marketed. Here, a
photomultiplier detector is used to measure the luminescence
produced in the gas phase reaction between ozone and NO.
This method directly measures NO rather than N02« It is
mentioned here because it forms the basis for a reliable differ-
a reducing medium
N02 to NO. Subse-
quent reaction of NO, thus formed, with ozone produces chemilumi-
nescence equivalent to NO , where NO- = NO - NO. The sensitivi-
ty of this method is reported as 0.1)1 ppm. To date, sufficient
ential measurement of NOo through the use of
such as stainless steel at 230°C, to convert
478
Out
Dehumidifier
IR source
Detector
Sample cell Interference
Mil
Chopper Comparison cell
Amplifier
Recorder
nzc
Control section
Figure 7.2-18
Diagram of Nondispersive Infrared Analyzer
479
field experience has been obtained to indicate the overall relia-
bility of the instrument over long periods of operation.
Ozone
The first chemiluminescence approach to a specific ozone
determination probably was developed by Regener (1960) Regener
found that, when air containing ozone contacts the surface of a
plate prepared by absorbing rhodamine B on silica gel, a lumi-
nescence is produced from the chemical reaction. The intensity
of the luminescence is proporat i onal to the concentration of
ozone present to concentrations as low as 0.001 ppm.
Regener's detector was found to
of interferences, such as NO?* It was
Nederbracht (1965) detector, wnich employs
of the ethylene reaction with ozone.
be subject to a number
soon f o 1 1 owed by the
the chemiluminescence
A number of commercially available analyzers have now
been marketed. It appears that the ozone-ethyl ene chemi 1 umi ne s-
cent reaction, having been adopted by the EPA as a standard
method for ozone, will soon become the basis for the common
continuous ozone field analyzer. Figure 7.2-19 presents a schem-
atic of a continuous chemiluminescence ozone meter.
Hydrocarbons
Commercial instruments that automatically measure
hydrocarbons fall into two main categories:
1. The total hydrocarbon continuous monitor, and
2. The semi cont i nuous nonmethane hydrocarbon monitor.
Briefly, automatic monitoring of hydrocarbon levels
depends on the fact that most organic compounds easily pyrolyze
when introduced into an air- hydrogen flame. This pyrolysis
produces ions that are collected either by the metal of the flame
jet itself (charged negative) or by a cylindrical collecting grid
(positively charged) that surrounds the flame. The sensitivity
to organic materials varies slightly depending on the number and
kind of ions. As a general rule, however, detector response is
in proportion to the number of carbon atoms in the chain of the
organic molecule. Thus, propane (three carbon atoms) gives
roughly three times the intensity of response as does methane,
and so on .
This "nonselectivity" is both an advantage and a dis-
advantage, depending on the information expected from the air
analysis. Nonselectivity toward hydrocarbons, but selectivity
in the sense that other compounds do not cause response, provides
this continuous instrument with the capability of measuring the
whole general class of organic compounds without concern for
interference. When the instrument response is calibrated using
480
so*. ( i : :
S*u' on \
v<uv[
g
X
140 mm B*0O*S
HO* MfTIR
CM.
BROOfS NfJOlf V»iV[
/
HI
v
I
PirOf I RUCtiO*
ChAMH*
tk
0 1 ? IITIR WIN
. 0 lbO mm BROOKS
llOWMl'tR
(*iRChu[i MinfR
»S9 HO* R(CUL*I0*
C»S' VACUUM
' Rlllif VAlVl
© o
1 — [IH*US1
1hom»^ INOUS'RKS
lO'CA'.C D'ARmRacv
PUMl
Figure 7.2-19
Diagram of Air-Ethylene System for
Continuous Chemi luminescent Ozone Meter
401
methane, the continuous strip chart readout is then a record of
the real-time variation in ambient hydrocarbons as though they
were 100% methane .
The Federal ambient air quality standard of 0.24 ppm
(6:00 to 9:00 a.m.) average for nonmethane hydrocarbons necessi-
tates the selective measurement of this class of compounds in
preference to total hydrocarbons, especially when elevated levels
of ozone are either known or suspected.
This analysis is accomplished by a differential meas-
urement using the following procedure. First, small measured
volumes of air are delivered intermittently (4 to 12 times/hr) to
a flame ionization detector to measure total hydrocarbons.
Following this measurement, another similar sample volume is
admitted into a stripper column, which removes the relatively
heavy non-methane hydrocarbons and water. The effluent from this
column, consisting of methane and CO, then enters a gas chromato-
graph for separation. The methane, which exits first, passes
unchanged through a catalytic reduction tube and into the detec-
tor, where it is recognized as methane. Carbon monoxide, which
exits next, passes through a pi at i num- hydrogen reducing atmos-
phere, and emerges as methane. It is thus detectable by the ion-
izing flame where it is electronically recognized as CO.
Nonmethane levels for these sequential samples results
from subtracting the signal of the methane hydrocarbons from the
total hydrocarbons where nonmethane HC = total HC - methane HC.
7.2.4
Monitoring Program Operation
Monitoring programs require a diversity of skills for
the successful management of a complete program. Key components
of a monitoring program include:
Si te Sel ect i on
System Desi gn
Equipment Selection and Purchase
Initial Calibration and Installation
Onsite Surveillance, Maintenance and Repair
Quarterly Calibration
Data Handling, Reduction, Summarization and Analysis
Qual i ty Assurance
Report Preparation
The costs associated with air quality and meteorological
monitoring programs can be enormous. Therefore, it is important
to isolate the specific data requirements necessary for a partic-
ul ar study area .
Tables 7.2-1 and 7.2-2 recommend various types of air
monitoring and meteorological instrumentation that can provide
reliable data necessary for air quality/meteorological analyses.
482
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tion as presented in the tables include the purchase price only.
Table 7.2-3 provides a review of total program costs as a func-
tion of the various components as detailed above. The range of
cost varies from a simplistic approach (e.g., particulate sam-
pling) to the sophisticated (e.g., full PSD permit support moni-
toring of gaseous, particulate and meteorological parameters).
The prices vary from approximately $10,000 to $200,000 for a year
of monitoring. A sophisticated, multiple site program can easily
cost over one million dollars.
Figure 7.2-20 presents a schedule for the completion of
a one-year monitoring program which indicates a 16 month period
from project inception to completion. This schedule assumes that
no problems arise. Realistically, it often takes two years to
obtain one year of data.
489
Table 7.2-3
Summary of Monitoring Program Costs
Site Selection -$1000
System Design ~$ 500 - $3000
Equipment Selection and Purchase -$2000 - $100,000
Installation and Initial Calibration ~$ 500 - $5000
Onsite Surveillance, Maintenance and Repair -$5000 - $50,000
Quarterly Calibrations ~$ 500 - $5000
Data Handling, Reduction, Summarization and -$1000 - $10,000
Analysis
Quality Assurance ~$ 500 - $5000
Report Preparation -$1000 - $10,000
490
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491
7.3
UK I AH DISTRICT MONITORING REQUIREMENTS
Specific regions within the Ukiah District lack sub-
stantial air quality, dispersion meteorology and climatological
data necessary for Environmental Impact Statement (EIS) devel-
opment and would require ons i te air quality and/or meteorological
monitoring programs to supply supportive data for future analy-
ses. Table 7.3-1 provides an evaluation of the adequacy of the
current data base for air quality impact analyses for lands
currently under BLM jurisdiction. A satisfactory rating indi-
cates that sufficient data exists within the particular area to
provide s i t e- s pec i f i c information necessary to accurately de-
scribe the air quality/meteorological baseline. An unsatisfac-
tory rating indicates that insufficient site-specific data are
available for use in future EIS level analyses.
As outlined in Table 7.3-1, climatological data are
readily available for all BLM lands in the Ukiah District. These
data are generally adequate for accurate si t e- spec i f i c assess-
ments. On the other hand, considerable data resolution would be
necessary for s i t e- speci f i c dispersion meteorology and air quali-
ty assessments for the various BLM land areas in the Ukiah Dis-
trict.
Coastal Region
For BLM lands located in the coastal region, climatolo-
gical data are generally satisfactory for any analysis that would
be required for BLM lands. Dispersion meteorological data are
generally acceptable in terms of the basic parameters wind speed,
wind direction and atmospheric stability. More sophisticated
data on winds aloft and mixing height are generally not satisfac-
tory in any portion of the Ukiah District. Air quality data are
only satisfactory along the coastal area in terms of total sus-
pended particulates. Onsite monitoring would be recommended for
the remainder of the criteria pollutants as well as visibility.
Coastal Mountains - Northern Area
Climatological data are once again satisfactory for the
preparation of climatological analysis for this portion of the
Ukiah District. Dispersion meteorological data, however, are
almost completely lacking and are unsatisfactory for an analysis
of the ventilation potential of this region. The Geysers KGRA is
one exception to the unsatisfactory nature of the data base in
the northern portion of the coastal mountains. In this region,
considerable meteorological, air quality and gaseous tracer
studies have been conducted around the Geysers thermal area.
Air quality data in this portion of the District are
generally unsatisfactory with the exception of total suspended
particulates. Monitoring for the criteria pollutants is general-
ly only conducted in the metropolitan portion of the Distict in
the extreme south and visibility data tend to be lacking through-
out the District.
492
Table 7.3-1
Summary of the Adequacy of CI imatological , Dispersion
Meteorological and Air Quality Data for BLM Lands in the Ukiah District
BLM Land Areas
A
B
C
Parameters
Coastal
Coastal Mountains
Northern Area
Coastal Mountains
Southern Area
Climatology
Temperature
Precipitation
Others
Dispersion
Meteorology
Wind Speed
Wind Direction
Stabil ity
Winds Aloft
Mixing Height
Air Quality
TSP
so9
NOx
03X
CO
Visibility
Satisfactory
Satisfactory
Satisfactory
Satisfactory/ A
Satisfactory^ '
Satisfactory
Unsatisfactory
Unsatisfactory
Satisfactory
Unsatisfactory
Unsatisfactory
Unsatisfactory
Unsatisfactory
Unsatisfactory
Satisfactory
Satisfactory
Satisfactory
Unsatisfactory),^
Unsatisfactory,,,;
Unsatisfactory^ '
Unsatisfactory
Unsatisfactory
Satisfactory
Unsatisfactory
Unsatisfactory
Unsatisfactory
Unsatisfactory
Unsatisfactory
Satisfactory
Satisfactory
Satisfactory
Satisfactory/, I
Satisfactory^ '
Satisfactory
Unsatisfactory
Unsatisfactory
(3)
Unsatisfactory),^
Unsatisfactory/.^
Unsatisfactory^ '
Satisfactory ,**
Unsatisfactory^ '
Unsatisfactory
Satisfactory - Sufficient site-specific data to accurately describe a particular
parameter for future EIS analyses.
Unsatisfactory - Insufficient site-specific data to accurately describe a particular
parameter for future EIS analyses.
Local terrain features will result in dispersion characteristics not well defined
by the available data.
2
Primarily for BLM Lands in northern Mendocino and eastern Humboldt Counties.
3
Unsatisfactory in Colusa County.
4
Satisfactory in Napa County.
49.3
Coastal Mountains - Southern Area
As described for the other two portions of the Ukiah
District, climatological data are once again satisfactory.
Dispersion meteorological data are satisfactory in terms of the
basic parameters wind speed, wind direction and atmospheric
stability but are unsatisfactory for the more sophisticated
parameters winds aloft and mixing height. These latter parame-
ters are generally only available at major National Weather
Service stations and as a result of site specific studies con-
ducted by applicants for major power development projects. Air
quality data in this region are again largely unsatisfactory with
the exception of ozone for which sufficient data exists.
Future Monitoring
The monitoring requirements required in support of air
quality permit applications are an oblibligation of the Appli-
cant. The data have been presented to inform the Federal Land
Manager (FLM) of monitoring requirements, as the role of the FLM
in the protection of air quality has increased in recent years.
The 1977 Amendments require the FLM To take an active role in
E PA ' s PSD permit process. In addition, the FLM must actively
protect the "air quality related values", primarily visibility,
of Class I Areas (i.e., national parks, monuments and wilderness
areas [See Section 6.4]).
towa
v i s i
must
t i ve
stud
expa
i ncl
Nort
New
pact
pi es
t rac
The FLM is
rd meet i ng the
b i 1 i t y in Class
be esta bl i shed
Agreement wi t h
i es for Class I
charged with ensuring "reasonable progress"
national goal of remedying impairment to
I Areas. To do this, a visibility baseline
BLM is presently entering into a Coopera-
the EPA which will begin visibility baseline
areas in California. This program will be an
nsion of the EPA's Western Fine Particulate Network which
udes forty stations uniformly distributed throughout Montana,
h Dakota, Wyoming, South Dakota, Utah, Colorado, Arizona and
Mexico. The purpose of this study is to determine the im-
s of western energy resource development. Particulate sam-
are taken twice weekly and undergo mass concentration and
e element analysis.
The visibility monitoring program will include two
initial site locations. One site will be located in the Susan-
ville District and one within a desert area of the Riverside
District as mandated by the EPA. The objective of the program is
to measure visibility, aerosal characteristics and climatology in
remote areas influenced by industrial expansion and population
growth. The program is also to differentiate between natural and
man-made contributions to visibility degradation.
In addition to sophisticated visibility measurements by
telephotometers, nephelometers and color photography, size segre-
gated particulate sampling will be conducted with subsequent
494
trace element analysis. The measurement program will be sup-
ported by basic meteorological monitoring including wind speed
and direction, temperature and relative humidity.
Baseline visibility is poorly defined in the Ukiah
District. However, monitoring programs should emphasize those
areas that incorporate or are adjacent to Class I areas. There-
fore, visibility monitoring would be recommended near either the
Point Reyes National Seashore or the Redwood National Park.
495
7.4
GLOSSARY OF TERMS
Ace uracy
Anisotropic
Turbul 1 ence
B i - V a n e
Chemil uminescence
Chromatograph
Col on" met ry
Conductivity
Constant Level
Bal 1 oons
Cou 1 ometry
Durab i 1 ty
The closeness of the instrument output to the
true value of the parameter.
Turbulence which is directionally dependent.
A wind direction instrument designed to rotate
around a vertical axis to measure the azimuth
and elevation angle of the wind.
The use of a phot om u 1 t i pi i er detector to
measure the luminescence produced in a gas
phase reaction between two species.
Analyzers used for the separation and measure-
ment of volatile compounds and of compounds
that can be quantitatively converted into
volatile derivatives.
The measurement or analysis of shade, tint,
value, brightness and purity of a color.
The property or power of conducting or trans-
mitting heat, electricity, etc.
Constant level balloons are used to determine
the trajectory of an air parcel at a desired
pressure level during a given time interval.
A method used in microanalysis to determine
quantities in solutions by measuring the
amount of electricity required to effect a
chemical change.
The ability of an instrument to survive vi-
brations and shock encountered in transporta-
tion, rough handling and normal operating
cond i t i ons .
Dustfal 1
Dynamic Response
Fl ame Ioni zat i on
The simple collection of dust due to gravita-
tional settling.
The real time reaction of an instrument.
The ionization of gas samples through their
introduction into an air hydrogyn flame.
Species specific ions are then measured by a
detector which measures ion intensity result-
ing from the flame ionization of any organic
compound .
496
Fl ame Photometry
Gri ess-Sal t zman
Method
Hi gh- Vol ume
Hydrot hermograph
Nephel ometer
Net Rad i at i on
Net Radiometer
Nond i spers i ve
Infrared
Ab sorpt i on
Pilot Balloon
Precision
Psychrometer
Pyranometer
Pyrhel i ometer
Rad i osonde
The use of a hydrogen rich air flame to induce
the emission of excited atoms specific to the
pollutant being measured.
A continuous colorimetric method for NU?
detection.
The collection of particulate matter on a
filter medium through the collection of an air
sample at a continuous standard rate.
An instrument for the measurement of tempera-
ture and humidity through the use of human
hairs which increase or shorten as a function
of atmospheric moisture content.
An instrument which indicates visibility
impairment due to the presence of particulate
matter in the atmosphere.
The difference between the total incoming
radiation and the outgoing terrestrial radia-
tion.
An instrument for the measurement of net
radiation.
The use of the principal whereby gaseous
compounds absorb infrared radiation at specif-
ic wave lengths. In nond i spers i ve absorption,
a detector is exposed to a wide wave length
band of rad i at i on .
A method for the measurement of wind velocity
and wind direction as a function of height
using a gas filled free balloon.
The degree of closeness of a series of read-
ings of an unchanging parameter.
An instrument which combines a dry bulb and
wet bulb thermometer for the subsequent calcu-
lation of humidity.
An instrument used to measure direct radia-
tion.
An instrument used for the continuous measure-
ment of direct solar radiation.
The use of a free balloon to carry meteoro-
logical sensors and a radio transmitter aloft.
497
Rawi nsonde
Rel i abi 1 i ty
Sensiti vity
Sim pi i c i ty
T-Sonde
Theodol i te
Total Radiation
Transm issometer
UVW Anemometer
A method of measuring winds aloft using a gas
filled free balloon and radio direction find-
ing apparatus, usually radar.
The ability of an air quality or meteorologi-
cal instrument to provide reprod uceabl e re-
sults.
The smallest change in the measured variable
that causes a detectable change in the output
of the inst rument .
Describes an instrument that can be operated
by an individual through the use of Standard
Operating Procedures.
The use of a free balloon to carry a tempera-
ture sensor and radio transmitter aloft.
An optical system used to measure the azimuth
and elevation angle of a pilot balloon.
The direct radiation from the sun plus the
diffuse radiation from the sky.
An instrument used for the measurement of
visibility through the measurement of the
transmission of light over a fixed baseline.
Usually on the order of 500 - 700 feet.
An anemometer designed to measure wind speed
in the horizontal (x and y directions) and
vert i cal .
498
BIBLIOGRAPHY
Angell , J.K. and Pack, H.J., "Analysis of Some Preliminary Low
Level Constant Level Balloon, (Tetroon) Flights." Monthly
Weather Review, 88, pages 235-248, 1960.
Cooke, T.H. "A Smoke Trail Technique for Measuring Wind" - Quar-
terly Journal of the Royal Meteorological Society, 8_8, pages
83-88, 1962.
U.S. Department of Health, Education and Welfare, "Air Qual i ty
Criteria for Sulfur Oxides" Chapter 2, page 21, Washington,
D.C. , January, 1969.
U.S. Environmental Protection Agency, Ambient Monitoring Guide-
lines for Prevention of Significant Deterioration (PSD)", EPA
450/Q-78-019, May, 1978 (OAQPS No 1.2-096).
AUbratV
edera\ Center
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QC 882
Baseline meteorology and ai:
quality in the Ukiah Distr
OVERLAY A
BLM LANDS UKIAH DISTRICT
20
_L_
40
I
MILES
BUREAU OF LAND
MANAGEMENT DOMAIN
60
_J
OVERLAY B
UKIAH DISTRICT TOPOGRAPHY
ELEVATIONS
DUUU
3000
1500
500
0
^
W SAC RAMI.NTl]
OVERLAY C
CLIMATIC ZONES FOR UKIAH DISTRICT
COASTAL MOUNTAIN
SACRAMENTO
OVERLAY D
MEAN ANNUAL TEMPERATURE CONTOURS (°F)
60
OVERLAY E
MEAN ANNUAL PRECIPITATION (INCHES)
SAN RAFAEL •
OVERLAY F
CALIFORNIA AIR BASINS IN THE UKIAH DISTRICT
j NORTH COASTAL MOUNTAINS
OVERLAY G
MANDATORY CLASS I AREAS UNDER 1977 CLEAN AIR ACT AMENDMENTS
ELK VALLEY
Redwood National Park
ONLY THE WILDERNESS
PORTIONS ARE DESIGNATED
CLASS I
W. SACRAMENTO
Point Reyes National Seashore*
m
ell, J.K. an
Level C
Weather
ke, T.H
t
CHAMPION W|0 90
LASR IN 9 „
x 12