THE ORIGIN AND FATE OF AIRBORNE POLLUTANTS

WITHIN THE SAN JOAQUIN VALLEY

VOLUME 4 - SUMMER FIELD STUDY

by

Meteorology Research, Inc. California Institute of Technology Division of Chemistry and Chemical

T. B. Smith Engineering D. E. Lehrman

D. D. Reible F. H. Shair

Prepared for California Air Resources Board

June 1981

The statements and conclusions in this report are those of the Contractors and not necessarily those of the State Air Resources Board. The mention of commercial products, their source or their use in connection with material reported herein is not to be construed as either an actual or implied endorsement of such products.

ii

ABSTRACT

An extensive observational proqram, lasting from November 1978 until

October 1979, was carried out to investigate the origin and transport of

pollutants in the San Joaquin Valley. Field studies were conducted during

the winter, summer and fall. Volume 3 describes the results of the November

15, 1978-December 10, 1978 intensive field study, along with two additional

tracer experiments conducted during relatively stagnant conditions in February

1979 and March 1979. The present volume (Volume 4) describes the summer

(July 1979) program. Volume 5 describes the fall (September 1979) program.

Participants in this study were Meteorology Research, Inc., California

Institute of Technology, Rockwell International (EMSC) and Environmental

Research and Technology (ERT). Six tracer releases provided the core of the July 1979 field program.

These releases were supported by supplementary meteorological observations

and airborne air quality sampling. Three Rockwell International vans,

located at Modesto, Merced and Madera, operated continuously to provide

additional air quality data. Filter samples obtained at each of the vans

were analyzed by ERT to investigate the particulate chemistry in the area.

The July 1979 field program was characterized by relatively warm

temperatures at the 850 mb level compared to the previous five-year average

suggesting conditions more conducive than average for pollutant buildup.

Maximum ozone concentrations observed during the July 1979 tracer

studies ranged from 0.11 to 0.17 ppm and were relatively uniform throughout

the valley. During the tracer studies, maximum carbon monoxide concen­

trations ranged from 2 to 5 ppm, and maximum NOx concentrations ranged from

0.18 to 0.32 ppm; both the CO and NOx concentrations reflected strong urban

sources and were closely related to peak traffic periods.

During July, the average wind flow into the valley at Stockton and

Los Banos was a11 hours of the day.

At Fresno and Visalia the low level winds were usually from the southeast

during the early morning but from the northwest during the rest of the day;

the duration of the southeasterly winds was longer at Visalia, associated

i i i

with the northward spreading of the "Fresno eddy" which develops during the

night as a result of stable conditions in the southern end of the valley.

Tracer released from Manteca during the morning of 7/13/1979 was

transported by northwesterly winds along Highway 99 for about 40 miles and

then along the San Joaquin River the lowest portion of the valley). The

tracer released from Manteca during the afternoon of 7/16/1979 was also

transported along the San Joaquin River. Horizontal and vertical rates of dispersion of the tracer were consistent with neutral or slightly unstable

atmospheric conditions, during both tests.

Tracer released from Livermore during the afternoon of 7/18/1979 was

transported by westerly winds over Altamont Pass and into the San Joaquin

Valley. On the day following the release, the tracer "cloud" was transported

down the western side of the valley in a manner similar to that found during

the releases from Manteca.

Tracer released from Reedley during the afternoon of 7/25/1979 was

initially transported by the upslope winds into the national forest and park

areas of the Sierra Nevada Mountains. Some of the tracer was then trans­

ported by the nighttime downslope winds and finally impacted regions on the

western side of the valley. Tracer released aloft into the nighttime jet was transported to the

extreme southern end of the San Joaquin Valley by late morning of the day

following the release. The nocturnal jet appears to be an efficient mech­

anism of transport to the southern end of the valley, but minimal ground level

impacts occur until the surface mixing layer deepens during the following

day.

Tracer released from Pacheco Pass during the afternoon of 7/30/1979

was carried aloft and essentially none was detected at ground level within

the valley.

In summary, pollutants transported into the San Joaquin Valley from

the California Delta, San Francisco Bay and Livermore regions were found to

primarily impact the western side of the northern half of the San Joaquin Valley.

The meteorological conditions during the summer are much less con­

ducive to pollutant build-up than the relatively stagnant conditions which

often occur during the winter.

iv

The principal exit region for pollutants from the valley is the

Tehachapi mountain ridge which forms the southeast border of the valley.

The upslope flow along the north-south edges of the valley is relatively

inefficient in removing pollutants because of its diurnal nature and the

broad width of the valley. Consistent with the influx of air at the mouth

of the valley, the transport within the valley was generally southward.

The nocturnal jet enhances this southward movement and provides a mechanism

for distributing pollutants throughout the valley.

V

1.

2. 2.1 2.2 2.3 2.4

3. 3.1

3.2

3.3

3.4

3.5

3.6

4.

Table of Contents

Introduction

Overview of the Meteorology and Air Quality Introduction Meteorology Air Quality Particulates

Tracer Surrmaries Test 1 13-14 July 1979,

(0700-1300 PDT) Test 2 16-17 July 1979,

(1300-1900 PDT) Test 3 18-19 July 1979,

(1510-2030 PDT)

Manteca Release

Manteca Release

Livermore Release

Test 4 25 July 1979, Reedley Release (1200-1700 PDT)

Test 5 27-28 July 1979, Airborne Herndon-Chowchilla Release (2300-0215 PDT)

Test 6 30 July 1979, Pacheco Pass Release (1200-1725 PDT)

Conclusions

Page

1-1

2-1 2-1 2-1 2-18 2-25

3-1

3-1

3-33

3-66

3-89

3-112

3-130

4-1

vi

LIST OF TABLES

Table No, Page

2.2.1 2.2.2 2,2.3

2.3.1 2.3.2 2.3.4 2.3.5

2.4.1

2.4.2

3.1.1 3. 1.2 3. 1.3 3, 1.4

3.1.5

3.2.1 3.2.2 3.2.3 3.2.4

3,2,5

3.3.1 3.3.2 3.3.3 3,3.4

3,4.1 3.4.2 3.4.3 3.4.4

3,5.1

3.6.1

Average Surface Pressure Gradients (July 1979) 2-3 1000-foot Resultant Winds (m/s) - July 1979 Average Wind Components* Along Valley Axis (July 2-7

Maximum Hourly Concentrations (ppm) July 2-19 Maximum Hourly Concentrations (ppm) July 2-20 Average NMHC Concentrations (ppb) July 06-09 PST 2-23 Time of Maximum Concentrations PST July 1979 2-24

Average Total Particle diameter<~ 20 µm) Concentrations Measured During July 1979 2-25 Estimated Contributions of Source Types to Average Fine Particle Mass During July 1979 2-27

Surface Winds at Manteca 13 July 1979 3-3 Aircraft Mixing Heights July 13, 1979 3-11 Maximum Hourly Concentrations July 13, 1979 3-14 Air Quality Measurements CARB San Joaquin Valley Project July 13, 1979 Sampling 3-16 Air Quality Measurements CARB San Joaquin Valley Project July 13, 1979 Sampling 3.... 17

Surface Winds at Manteca 16 July 1979 3-35 Aircraft Mixing Heights July 16-17, 1979 3-40 Maximum Hourly Concentrations July 16, 1979 3-42 Air Quality Measurements CARB San Joaquin Valley Project July 16, 1979 Sampling 3-44 Air Quality MMesurements CARB San Joaquin Valley Project July 17, 1979 Sampling 3-45

Surface Winds at Livermore 18-19 July 1979 3-68 Aircraft Mixing Height July 18, 1979 3-70 Maximum Hourly Concentrations July 18, 1979 3-74 Air Quality Measurements CARB San Joaquin Valley Project July 18, 1979 Sampling 3-78

Low-Level Winds 25-26 July 1979 3-91 Aircraft Mixing Heights July 25, 1979 3-96 Maximum Hourly Concentrations July 25, 1979 3-98 Air Quality Measurements CARR San Joaquin Valley Project July 25, 1979 Sampling 3-99

Maximum Hourly Concentrations July 27, 1979 3-118

Maximum Hourly Concentrations July 30, 1979 3-134

vii

LIST OF FIGURES

Figure No. Page

2.2.1 850 mb Temperatures - July 1979 2-2 2.2.2 Comparison of Wind Component (600 m) and Pressure Gradient 2-4 2.2.3 Comparison of Wind Component (600 m) and Pressure Gradient 2-6 2.2.4 Average Wind Components Along Valley Axis July 1979 (05 PDT) 2-9 2.2.5 Average Wind Components Along Valley Axis July 1979 (09 PDT) 2-10 2.2.6 Average Wind Components Along Valley Axis July 1979 (13 PDT) 2-11 2.2.7 Average Wind Components Along Valley Axis July 1979 (17 PDT) 2-12 2.2.8 Average Wind Components Along Valley Axis July 1979 (21 PDT) 2-13 2.2.9 1000 Ft-agl Streamlines - 18 July 1979 (21 PDT) 2-15 2.2.10 1000 Ft-agl Streamlines - 18 July 1979 (05 PDT) 2-16 2.2.11 Component Winds Along Valley Axis (Fresno) July 27-28, 1979 2-17

3.1.1 Surface Weather Charts - 13 July 1979 (05 PDT) 3-2 3.1.2 1000 Ft-agl Streamlines - 13 July 1979 (07 PDT) 3-4 3.1.3 1000 Ft-agl Streamlines - 13 July 1979 (09 PDT) 3-5 3.1.4 1000 Ft-agl Streamlines - 13 July 1979 (13 PDT) 3-6 3.1.5 1000 Ft-agl Streamlines - 13 July 1979 (19 PDT) 3-7 3.1.6 1000 Ft-agl Streamlines - 14 July 1979 (03 PDT) 3-8 3 .1.7 Vertical West-East Cross Section of Wind Component (m/s)

to Valley Axis - 13 July 1979, 07 PDT 3-10 3.1.8 Maximum Hourly Ozone Concentrations (pphm) - 13 July 1979 3-12 3.1. 7 Vertical West-East Cross Section of Ozone Concentrations (ppb)

Measured Between 0646-0916 PDT - 13 July 1979 3-13 3 .1.10 Sampling Routes 13 July 1979 3-15 3.1.11 Aircraft Sounding - 13 July 1979 3-19 3.1. 12 Aircraft Sounding - 13 July 1979 3-20 3.1.13 Aircraft Sounding - 13 July 1979 3-21 3.1.14 Aircraft Sounding - 13 July 1979 3-22 3.1.15 SF5 Release - Manteca 13 July 1979 3-24 3.1. 16 Sampler Locations 3-25 3.1.17 Highway Traverses 3-28 3.1.18 Gaussian Comparison 3-29 3.1.19 Tracer Trajectory 3-31 3.2.1 Surface Weather Charts - 17 July 1979 (05 PDT) 3-34 3.2.2 1000 Ft-agl Streamlines - 16 July 1979 (13 PDT) 3-36 3.2.3 1000 Ft-agl Streamlines - 16 July 1979 (19 PDT) 3-37 3.2.4 1000 Ft-agl Streamlines - 17 July 1979 (09 PDT) 3-38 3.2.5 Component Wind (m/s) From Turlock - 16 July 1979 3-39 3.2.6 Maximum Hourly Ozone Concentrations (pphm) - 16 July 1979 3-41 3.2.7 Sampling Routes - 16 July 1979 3-43 3.2.8 Aircraft Sounding - 16 July 1979 3-46 3.2.9 Aircraft Sounding - 16 July 1979 3-47 3.2.10 Aircraft Sounding - 16 July 1979 3-48 3.2.11 Aircraft Sounding - 16 July 1979 3-49 3.2.12 Aircraft Sounding - 16 July 1979 3-50 3.2.13 Aircraft Sounding - 17 July 1979 3-52 ..,, t"\ 1 A

J.l.l'+ Aircraft Sounding - 17 July 1979 3... 53 3.2.15 Aircraft Sounding - 17 July 1979 3-54 3.2.16 Aircraft Sounding - 17 July 1979 3-55 3.2.17 SF5 Release - Manteca 17 July 1979 3-58

Vii i

LIST OF FIGURES (Continued)

Figure No. Page

3.2.18 3.2.19 3.2.20 3.2.21 3.3.1 3.3.2

3.3.3 3.3.4 3.3.5 3.3.6 3.3.7 3.3.8 3.3.9 3.3.10 3.3.11 3.3.12 3 .3.13 3.4.1 3.4.2 3.4.3 3.4.4 3.4.5

3.4.6 3.4.7 3.4.8 3.4.9 3.4.10 3 .4.11 3.4.12 3.4.13 3.4.14 3.5.1 3.5.2

3.5.3 3.5.4 3.5.5 3.5.6 3.5.7 3.5.8 3.5.9 3 .5.10 3.5.11 3.5.12 3.6.1 3.6.2

3.6.3 3.6.4 3.6.5 3.6.5

Sampler Locations - Test 2 3-59 Highway Traverses 3-61 Gaussian Comparison 3-62 Tracer Trajectory 3-65 Surface Weather Charts - 18 July 1979 (05 PDT) 3-67 Time-Height Cross Section Component Winds (m/s) From Altamont Pass 18-19 July 1979 3-69 1000 Ft-agl Streamlines - 18 July 1979 (15 PDT) 3-71 1000 Ft-agl Streamlines - 18 July 1979 (19 PDT) 3-72 1000 Ft-agl Streamlines - 19 July 1979 (05 PDT) 3-73 Maximum Hourly Ozone Concentrations (pphm) - 18 July 1979 3-75 Sampling Routes 18 July 1979 3-77 Aircraft Sounding - 18 July 1979 3-79 Aircraft Sounding - 18 July 1979 3-80 Aircraft Sounding - 18 July 1979 3-81 SF5 Release - Livermore 3-84 Sampler Locations - Test 3 3-85 Tracer Trajectories 3-87 Surface Weather Charts - 25 July 1979 (05 PDT) 3-90 1000 Ft-agl Streamlines - 25 July 1979 (15 PDT) 3-92 1000 Ft-agl Streamlines - 25 July 1979 (23 PDT) 3-93 1000 Ft-agl Streamlines - 26 July 1979 (05 PDT) 3-94 Time-Height Cross Section Component Winds (m/s) from Cherry Gap 25 July 1979 3-95 Maximum Hourly Ozone Concentrations (pphm) - 25 July 1979 3-97 Sampling Routes 25 July 1979 3-100 Aircraft Sounding - 25 July 1979 3-102 Aircraft Sounding - 25 July 1979 3-103 Aircraft Sounding - 25 July 1979 3-104 SF5 Release - Reedley 3-106 Sampler Locations - Test 4 3-107 Air and Auto Traverse Comparison 3-108 Sampler Trajectories 3-111 Surface Weather Charts - 28 July 1979 (05 PDT) 3-113 Time-Height Cross Section Component Winds (m/s) from Madera 27-28 July 1979 3-114 1000 Ft-agl Streamlines - 27 July 1979 (23 PDT) 3-115 1000 Ft-agl Streamlines - 28 July 1979 (09 PDT) 3-116 1000 Ft-agl Streamlines - 28 July 1979 (11 PDT) 3-117 Maximum Hourly Ozone Concentrations (pphm) 27 July 1979 3-119 Wind Profiles Test 5, 27-28 July 1979 3-121 Nocturnal Jet Velocity Profiles 3-122 SF5 Release - Airborne 3-124 Sampler Locations - Test 5 3-125 Air Trav Data Comparison 3-126 Sampler Trajectories 3-128 Surface Weather Chart - 30 July 1979 (05 PDT) 3-131 Time-Height Cross Section of Through Pass Component of Wind (m/s) at Pacheco Pass - 30 July 1979 3-132 1000 Ft-agl Streamlines - 30 July 1979 (15 PDT) 3-133 Maximum Hourly Ozone Concentrations (pphm) - 30 July 1979 3-135 SF5 Release - Los Banos 3-138 Sampler Locations - Test 6 3-139

ix

1. Introduction

SurT111er months in the San Joaquin Valley are characterized meteor­

ologically by intense solar heating and generally clear skies. Strong frontal passages do not occur but weak cold air troughs move through the area resulting in changes in stability and fluctuating mixing heights.

These changes are reflected in significant day-to-day variations in pollutant levels in spite of the apparently small changes occurring in the synoptic weather charts. Fresno-Olive Street, for example, showed

maximum daily ozone concentrations ranging from .03 to .17 ppm during the month of July 1979.

The principal driving force for the low-level winds in the valley is the pressure gradient between the coast and the interior (east of the Sierra Nevadas, for example). The cold air trough passages serve to in­crease these surface pressure gradients and increase the flow into the valley from the northwest.

The strong solar insolation and the possibility of stagnation

episodes within the vaiiey raise serious questions concerning ozone for­mation during the summer months. Additional problems which were addressed during the summer field study were the transport of pollutants from the Bay area into the San Joaquin Valley, the role of the nocturnal wind jet in redistributing material throughout the valley and the effectiveness of upslope transport in removing pollution from the valley.

The summer field program consisted of six tracer releases as listed below. Each release was supported by pibal wind soundings and aircraft measurements. A network of five additional pibal stations was maintained independently during the field study by the California Air Resources Board (CARB). These stations were located at Stockton, Los Banos, Fresno, Visalia and Bakersfield, regardless of test location. Two pibal sounding stations supported by the field program itself were moved from test to test to obtain the best wind coverage possible.

Three Rockwell International vans were positioned to the east of Modesto, Merced and Madera to obtain surface air quality data. Environmental Research and Technology (ERT provided filter samplers which were operated at each van. Analyses and interpretation of the filter samples were carried out

1-1

by ERT. The Atmospheric Testing Branch of the CARB at El Monte obtained hydrocarbon samples several times daily at Stockton, Tracy, and at two locations in Fresno. A number of aircraft samples were a·lso obtained. The

samples were subsequently analyzed by CARB for C2 through C10• The following tracer releases were carried out during July 1979:

Release Location Date Release Time Jul_y 1979 PDT

Manteca 13 0700-1300

Manteca 16 1300-1900 Livermore 18 1510-2030 Reedley 25 1200-1700 Herndon to

Chowchilla (airborne) 27-28 2330-0215 Pacheco Pass 30 1200-1725

The present volume (Volume 4) discusses the details of the July field program including a11 pertinent tracer and aircraft sampling data (Appendix to Volume 4). Surface and pibal wind data have been furnished to CARB on magnetic tape. Separate reports (Volumes 6 and 7) give the details

of the Rockwell International and ERT work, respectively. Portions of these reports have been used in the present volume where appropriate.

Volumes 3, 4 and 5 of the report series cover the details of the three field programs. Volume 2 contains an extended summary of the entire program and a discussion of a number of special analysis topics which resulted from the field measurement program. Volume 1 is an Executive Summary of the program.

1-2

2. Overview of the Meteorology and Air Quality

2.1 Introduction

The following sections describe the general conditions which occurred during the July 1979 intensive field period. The overall meteor­ological conditions are summarized and compared to climatological records to determine the representativeness of the test period. Descriptions of

air quality and particulate concentrations for the intensive period are sunmarized from the more extensive reports by Rockwell International and ERT which appear as Volumes 6 and 7 of this report series.

2.2 Meteorology

850 mb Temperatures

Temperatures at the 850 mb level provide a simple indicator of the regional air pollution potential. Warm temperatures aloft create the

stability required to trap the pollutants in the lower layers. Figure 2.2.1 shows the daily variation in 05 PDT temperatures at

850 mb for Vandenberg AFB and Oakland during the month of July 1979. The five-year average temperatures for Vandenberg and Oakland are also shown in the figure.

After the first seven days of the month, the temperatures at 850 mb were generally above normal. Test dates are indicated in the figure. All tracer tests were carried out under conditions of above normal temperatures aloft. As indicated, Test 3 was conducted with the 850 mb temperature eight degrees above normal and represents the most stable episode period encountered during July.

Surface Pressure Gradients

In the absence of major changes in synoptic weather patterns during July, the principal driving force for winds in the San Joaquin Valley results from lower surface pressures east of the Sierras relative to the coastal areas.

Strong surface heating in eastern California and Nevada causes a low pressure, thermal trough to persist throughout most of the summer.

2-1

.,,..,.,,.,,·'

'·\i -Five Year

I Average ------- -...-20

u I \,~

"' ,_ w

=> er 10 l l l l l l

N w Tests I 2 3 4 5 I, "' I Q.N :,,:

,_w

Vandenberg

:;."' Oakland

Tracer Relei1ses0

1

5 10 15 20 25 30 Date

Figure 2.2.1 850 mb Temperatures - July 1979

ll/DZZ

Table 2.2.1 gives the average surface pressure gradients during

July 1979 between San Francisco Airport and Las Vegas. This parameter is

one indicator of the strength of the surface pressure gradient affecting

the valley. Other pressure differences could also be used. The table shows typical diurnal changes in pressure gradient with peak values in the late

afternoon when the results of the afternoon heating have taken effect.

Day-to-day relationships between surface pressure g~adients and

wind speeds are apparent but are occasionally masked by local effects not adequately measured by the simple, single pressure gradient parameter being

suggested above. Figure 2.2.2 shows the daily variations in pressure gradient

for July 1979 at 1600 PDT related to the 600-m winds at Los Banos and Stockton

at 1700 PDT. Wind speeds in the figure refer to the component directed along the valley axis with positive numbers referring to wind flow from Stockton

toward Bakersfield.

Table 2.2.1

Average Surface Pressure Gradients (July 1979) San Francisco-Las Vegas

Time Pressure Difference (PST) (mbs) 00 6.0

03 5.6

06 4.6

09 4.4 12 5.2

15 6.3

18 6.7

21 6.2

The pressure gradients in Figure 2.2.2 indicate lower than average

values throughout much of the month with the exception of two periods around

the 10th and 27th. Reference to Figure 2.2.1 indicates that the warm temper­

ature period during mid-month was associated with below average pressure

gradients.

2-3

1 0

"' ...... E:

C 5 w w CL. I V) ' ' / \. ...,_... STOCKTON ( 17 PDT)C

WIND COMPONENT ALONG VALLEY AXIS

z

3:

0

1 0 1 5 20 25 30 DA TE

.0

\J

E

.... z L.J... C C( IX (.!'

L.J IX :, V)

10 I 6 Year Average

VJ 5 L.J IX CL.

1 0 1 5 20

PDT PRESSURE GRADIENT (SFO- LAS VEGAS)

25 3 0 DA TE

81/054Figure 2.2.2 Comparison of Wind Component 600 m) and Pressure Gradient

July 1979

2-4

There is considerable similarity between the pressure gradient vari­

ations and the wind speed characteristics for Stockton and Los Banos. In

particular, the large pressure gradient values near the 10th resulted in

unusually strong wind flow. The pressure gradient peak on the 27th is also

somewhat reflected in the Stockton wind speeds. The primary difference

between the two plots occurs near the 20th when the major drop in pressure

gradient is only partly reflected in the Stockton-Los Banos winds.

A similar comparison of the San Francisco-Las Vegas pressure gradient

and the Bakersfield wind at 600 mis shown in Figure 2.2.3. In this case,

the minimum pressure gradient on the 20th shows up clearly as a negative

wind component at Bakersfield. The similarities in the two plots, in fact,

are quite pronounced with the exception of the peak pressure gradient on the

27th.

These figures indicate the association between surface pressure gradi­

ents and the flow along the valley axis but suggest that the details of the

wind response to gradient fluctuation may not be entirely consistent through­

out the valley. In particular, the northern and southern parts of the valley

may respond in somewhat different ways.

Valley Wind Characteristics

Pibal wind coverage during July 1979 was carried out for 22 days at

the five locations shown in Table 2.2.2. Observations were taken on virtually

every day at the times shown in the table. Additional observations were made

on test days but are not available for the entire 22 day period.

Resultant winds at 1000 feet (agl) for the 22-day period have been calculated by averaging wind components over the 22 days by time of day.

Principal features shown in the table are:

Northwest winds at Stockton and Los Banos at all hours. Southeast winds at Fresno (09 PDT) and Visalia (05 and

09 PDT) in association with the Fresno Eddy.

Peak winds at 21 PDT for most locations.

Light west to northwest winds at Bakersfield except for

late afternoon and evening.

2-5

l 0

"' ....... E

0 5 LW LW Q..

V')

C z: ...... ::i:

0

l 0 l 5 20

..c::,

~ LW .... 0 cc 0:: t!:)

LW

0:: ::, V')

V')

LW 0:: Q..

l 0

6 Year Average

5

PDT PRESSURE GRADIENT (SFO-

l 0 1 5 25 3 0

Figure 2.2.3 Comparison of Wind Component (600 m) and Pressure Gradient July 1979

2-6

BAKERS FI ELD ( 1 7 PDT)

WIND COMPONENT ALONG VALLEY AXIS

25 30 DATE

LAS VEGAS)

DA TE

81/055

Table 2.2.2

1000-foot Resultant Winds (m/s) July 1979

PDT 05 09 u i7 2i

Stockton 310°/4.4 319°/3.3 316°/3.5 321°/4.8 291°/7.4

Los Banos 304 /5.5 320 /4.1 341 /4.3 335 /5.1 328 /7.4

Fresno 338 /3.9 134 /2. 9 282 /2.5 303 /4.5 313 /7.7 Visalia 167 /2.4 169 /3.5 285 /2.1 316 /3.9 320 /4.6

Bakersfield 316 /1.0 276 /0.4 309 /1.9 317 /3.9 330 /2.7

Table 2.2.3 shows the average wind components directed along the axis

of the valley for July 1979. Surface wind components at Stockton are shown

together with 1000-foot components at all pibal locations. Positive values

indicate flow directed from Stockton to Bakersfield.

Table 2.2.3

Average Wind Components* Along Valley Axis (July)

a. Surface Winds (m/s) Location Time (PDT)

03 09 15 21

Stockton 2.0 2.7 3.9 3.5

b. 1000-foot Winds (m/s)

Location 05 09

Time (PDT) 13 17 21

Stockton 4.3 3.3 3.5 4.8 5.7

Los Banos 4.9 4.2 4.3 5.1 7.4

Fresno 3.8 -3.8 1.7 4.0 7.7

Visalia -2.1 -3.3 0.9 3.8 4.7 Bakersfield 1.3 0.2 1.8 3.8 2.7

* Negative components refer to southeasterly winds

2-7

As indicated in the table, flow is directed into the valley in the

lowest 1000 feet at all times of day. The negative values at Fresno and

Visalia result from the influence of the Fresno Eddy, Peak flow into the

valley occurs at 21 PDT. It is to be noted that the flow along the valley

is relatively constant at all locations at 17 PDT, suggesting a constant flux

into and out of the valley. For the other hours, however, continuity is not

maintained and it is clear that major areas of convergence and divergence

must exist.

The component values along the axis of the valley are shown in more

detail in Figures 2.2.4 through 2.2.8. Average profiles of the axis wind

component are shown for each location at 05, 09, 13, 17 and 21 PDT.

The principal features of interest in the figures are the following:

The average profiles at 17 PDT (Figure 2.2.7) are

similar at all locations.

The average profiles at Stockton and Los Banos

are similar at all times.

At 21 PDT the Visalia profile is similar to Fresno

but with slightly reduced speeds. The Bakersfield

profile at 21 PDT, however, shows a marked decrease

in velocity to 1000 m (agl) and an increase in speed

above that height. This is interpreted as the first

evidence of low-level blocking of the flow in the

southern end of the valley by stability and terrain.

It is apparent that a part of the flow is diverted

aloft to a level where escape over the terrain is

possible. This is considered to be the initiation of the Fresno Eddy.

At 05 PDT the effect of the blocking has extended up­stream to Visalia. Velocities are reduced in the

lowest 1000 mat both Bakersfield and Visalia but

increased aloft. This development is associated with

the spreading of the Fresno Eddy to the north.

2-8

'o I

I

f ),

y

\I

2500

~ \

t 2000 ~

e ~ ~

0 ,•I

z =:, 0 er '-'>

w 1500 ~ > 0 cc c::c ~ :i:::

.... ~ w :i:::

1000

500 -- STOCKTON I•---- LOS BANOS ------- FRESNO

I

f

I

•I•I I

•I

I I

,1 --VISALIA r _---BAKERSFIELD

•I

-5 0 5 r./s -5 0

Figure 2.2.4 Average Wind Components Along Valley Axis July 1979 (05 PDT)

8 ~

'-' ..,

I

I•

,' I f '

I

5 m/ s

II /049

2-9

2500

i 2000 ~

E-0 z :=, 0 ex: Cl

1500

1-:r:: Cl

LIJ :r::

l 000

-- STOCKTON ---- LOS BANOS ------- FRESNO

.•

I ,•

I

•I

I

•

I,•

--VISALIA ----BAKERSFIELD

0

500, .•· .... ' I

<( 1' , .. r ••·I•

-5 0 5 w,/ s -5 5 m/ s

11 /050

Figure 2.2.5 Average Wind Components Along Valley Axis July 1979 (09 PDT)

2-10

2500

2000 E ~

0 z :=, 0 c::: t!l

L..i 1500> 0 a:l < I-X t!l

L..i X

1000 -- STOCKTON

'~, - --- L,.U,;, BANOS ·····-· FRESNO

500

-5

Figure 2.2.6

. ;

•I

•' •

' •

J ; __ VISALIA I ~---BAKERSF!cL:)

I

I•I '•' •I

•I

I

•

0 5 11/ s -5 0

Average Wind Components Along Valley Axis July 1979 (13 PDT)

2-11

~ . ' . ~

I

• I. '

'

2500

2 000 ....... E ~

C z ::, 0 c:: c.:,

w 1500> 0 cc c:c I-:c: c.:,

w :c:

1000

500

F

SCK >Lose

. ~ ' '

__ SiOCKiOI\ BANOS---- LOS

•..•.•. FRESNO

f

• f :

\

~ \

' I I ~ ' ~. ·~ :

;

' -5

Figure 2.2.7

0 5 ., s -5 0

Average Wind Components Along Valley Axis July 1979 (17 PDT)

2-12

,, \ .I \

~

\ ~\

~ I

1,/J

5 II/ S

ll /052

• •

,~'-. \

•, \ '. ' ---. '-._

'_

"'

2500

2000 E

C z: :::, 0 c:: t.:,

1soo-

cC

1-::t: t.:, .... ..... ::t:

1000

Isoo+-

-- STOCKTON ---- LOS BANOS ------- FRESNO

-5

Figure 2.2.8

Loss

SC(!K~,F .

•.. .. I\ : .' .•

.• .\\··.·,. .

....

I

'· \

\'. ' ~ \ -I

··-.r h

I ;

,._) ,,~,.,.

.:.. -

0 5 .. , 5 -5

Averaae Wind Comoonents Along Valley Axis July 1979 (21 PDT)

2-13

V B

1 f\\ t '•

•

I ' • •

'• I

I• I\

•

1

•I I

•I

•

--VISALIA -- --BAKERSF!EU

' j• \

♦

~ '

' I ' I

/ •

0

81/053

By 09 PDT the blocking in the lowest 1000 m affects

the wind flow at Fresno. Both Visalia and Bakersfield

continue to show increased velocities above 1000 m.

Remnants of the low level blocking and increased

flow aloft continue as late as 13 PDT but to a

reduced degree. By 17 PDT the flow becomes rela­

tively uniform at all locations.

The foregoing leads to a physical picture in which the northwesterly

flow is blocked in the southern part of the valley by terrain as low-level

stability develops in the early evening. The low-level flow is diverted into a cyclonic eddy about 1000 m deep which gradually extends to the north as far

as Fresno. Some of the northwesterly flow approaching this eddy is deflected

aloft and is able to escape from the southern part of the valley at altitudes

above 1000 m.

Two phases in this development are shown in Figures 2,2.9 and 2,2,10,

At 21 PDT on July 18 (Figure 2.2.9) the flow in the valley was uniformly from

the northwest at 1000 ft agl. The wind speed at Bakersfield (3.7 m/s), how­

ever, was considerably less than at locations to the north, indicating the onset of the blocking effect. By 05 PDT of the following morning (Figure

2.2.10) the eddy at 1000 ft had extended as far north as Fresno.

Of the 22 days in July 1979 for which detailed pibal data were avail­

able, the Fresno Eddy formed on 18 days. There was no significant eddy on July 10, 11, 26 and 28. Reference to Figure 2.2.1 indicates that these days

were characterized by cold trough passages aloft, resulting in disruption of

the stabilizing conditions required for the eddy formation. Under these

slightly less stable conditions, wind flow can continue from the northwest

all night, transporting air out of the southern part of the valley.

Nocturnal Wind Jet

On numerous nights a nocturnal wind jet is observed to form in the

San Joaquin Valley, particularly in the Fresno area. Northwest winds in­

crease in the low levels, peaking at 21 to 23 PDT. An example is shown in

Figure 2.2.11 for the night of July 27-28 when a tracer release was made

into the center of the jet. The time section of valley axis wind components

2-14

...,

4 N i

. . . " . - --Figure 2.2.9 1000 Ft-agl Streamlines - 18 July 1979 (21 PDT)

2-15

•ta.I ~ft ! If If '.

. . . " . - . -,. ...... ,·.-·· ...... -

•.•

.... ,. Figure 2.2.10 1000 Ft-agl Streamlines - 19 Juiy 1979 (05 PDT)

2-16

0 0 0

\..., _.-o1711D ~ \ '-./\)

0

-- I \ E 1447 ~

~' C z :::::, 0 0:: <.!) 1170 ('Lu > 0 ... 3 a:l c(

846 I-:c <.!)

N ..... I,__. Lu

-..J :c 612 r-

313 I-

, I \ --... 3 __________,

' ~ \..@_ rT~ ~,,,3 m/s

0 0 81 /043

11 15 19 23 3 7 11 TIME ( PDT)

Figure 2.2.ll Component Winds Along Valley Axis July 27-28, 1979

(Fresno)

indicates increasing low level velocities beginning about 19 PDT with a peak near 300 m elevation at 23 PDT. The influence of the Fresno Eddy is shown by the negative wind values at 09 PDT.

The jet is caused by decreasing friction in the low layers accompany­ing the evening stabilization of the low levels. Under the influence of a strong driving force due to the existing pressure gradient, the air aloft accelerates resulting in relatively high velocities at low levels. During the 22 days of pibal data in July 1979, a strong jet occurred on nine nights while a moderate jet formed on four others. Further discussion of the

nocturnal jet is given in Volume 2.

2.3 Air Quality

Tables 2.3.1 and 2.3.2 give the maximum hourly concentrations of various parameters as observed during the July 1979 intensive field program. Concentrations were observed at Modesto (RI), Merced (RI) and Madera (RI) by Rockwell International vans. The remainder of the concentration data were obtained from CARB Air Quality Data. Similar data for the months of July 1977 and 1978 are also included for comparison.

Comparison of July 1977, 1978 and 1979 indicates that peak hourly con­centrations were very similar in all three years. It is therefore concluded that the pollutant conditions during the field period were as representative

of Juiy poiiutant episode conditions as could reasonably be expected.

Ozone

Maximum hourly ·concentrations of ozone in Table 2.3.1 indicate rather uniform values throughout the valley but with slightly higher concentrations near the major urban areas. A number of locations on the eastern side of the valley show maximum values above the federal standard of 0.12 ppm. There were eight days of exceedances at the Modesto (RI) site during July 1979 and five and eight exceedances at the Merced and Madera sites, respectively. Lowest hourly maxima occur on the western side of the valley. There appears to be little change over the three-year period 1977-79. Maximum concentrations recorded at the regularly reporting stations were .16, .16 and .17 ppm in the three years. Shaver Lake shows a peak hourly value of .13 ppm for each year, indicating the importance of upslope fiow from the valley.

2-lo

--------------------------------------------------------------------------------

Table 2.3.1

Maximum Hourly Concentrations (ppm) July

03 co Field Field

Location 1977 1978 1979 1977 1978 1979

Bakersfield .12 .13 .16 8 6 4

Coalinga .10 .10 1 2

Five Points .12 .08 .08 2 2

Fountain Springs .13 .13 Squaw Valley .13 .16

FNO-But 1er

FNO-CSU .17 2

FNO-Downtown

FNO-Olive .16 .15 .17 8 4 5 Hanford .12 .05 .11

Lindsay .11 .14

Los Banos .12 .13 .10

McKittrick Merced .14 .10 3 2

Modesto .12 .17 3 3 Oil dale .16 .14

Shaver Lake .13 .13 .18 2 2 1 Stockton .16 .14 4 3 Taft .09 .10

Turlock .15 .15 .16

Visalia .09 .13 .12 5 4

Modesto (RI ) .19 0.6

Merced (RI) .13 Madera RI .15 1.2

2-19

--------------------------------------------------------------------------------

Table 2.3.2

Maximum Hourly Concentrations (ppm)July

X 2 Field Field

Location 1977 1978 1979 1977 1978 1979

Bakersfield .38 .35 .27 .04 .08 . 06

Coalinga .04 .09

Five Points .02 .01

FN0-CSU

FN0-0live .43 .15 .18 .02 .02 McKittrick

Merced .24 .13

Modesto .22 .39 .02

0ildale .15 .15 •07

Stockton .23

Visalia .20 .17 .13

Modesto (RI ) .04

Merced (RI ) .03

Madera (RI) .02

2-20

co The maximum CO concentrations during July 1979 show the strong

influence of urban centers. Bakersfield and Fresno consistently record the

highest values in the valley, ranging from a peak value of 5 to 8 ppm in the three-year period. Peak hourly values of 1-2 pm'are typical for the rural areas and the west side of the valley.

Nitrogen Oxides

Nitrogen oxides (NOx) concentrations also reflect the influence of

urban areas. Generally, Fresno and Bakersfield report the highest hourly concentrations. In July 1979, however, there were four days at Modesto during the month which exceeded peak concentrations at any other location.

With the exception of Modesto, the peak hourly NOx concentrations during July 1979 appeared to be slightly lower than observed in 1977 and 1978. In the rural areas and the western side of the valley, NOx concentrations tend to be very low, frequently not exceeding .10 ppm.

Sulfur Dioxide

Sulfur dioxide concentrations in the valley were generally low during July 1979. Highest values were recorded at Bakersfield and Oildale where .06

and .07 ppm, respectively, were observed. The remaining maximum values measured in the valley were .01 to .02 ppm. These background values were the same as observed in July 1977 and 1978 but the concentrations for Oildale and Bakersfield were slightly lower than observed in the previous two years.

Hydrocarbons

Non-methane hydrocarbons (NMHC were measured at Stockton, Tracy and two locations in Fresno during July 1979. Samples were obtained and analyzed

by the Atmospheric Testing Branch, California Air Resources Board (El Monte). Samples were usually taken three times per day and subsequently analyzed for

C2 through C10-

2-21

Table 2.3.4 gives the average concentrations of various hydrocarbons

measured during July. Total NMHC averaged less than 200 ppb with the ex­

ception of Riverside which was influenced by one large sample of propane.

The automobile contribution to NMHC was low at all stations as suggested

by the low values of acetylene. Propane was the largest contributor to the

total NMHC concentration.

NOx concentrations were not obtained at Stockton during July 1979.

Concentrations of NOx at Union Island between 06 ad 09 PST ranged from .01

to .04 ppm. Values at Stockton may have been somewhat higher. Use of the

Union Island NOx values yields an average NMHC/NOx ratio of about 5 with

a range from 2 to 14 on individual days. The small concentrations of NMHC,

however, preclude the formation of much ozone, particularly in view of the

low concentrations of the more reactive forms of NMHC.

Time of Peak Hourly Concentrations

Table 2.3.5 gives the principal periods of the day when peak ozone

and NOx concentrations were observed at several stations during July 1979.

On some days, the peak concentrations occurred outside of the principal

period indicated. If such occurrences were sufficiently frequent the time

of day was included in the table in parentheses.

It is apparent from the table that there are two peak ozone periods

in the northern part of the valley. One of these occurs near or slightly '

after noon and can be attributed to local sources. The second occurs be-

tween 15 and 20 PST and must be associated with transport of ozone or pre­cursors into the area. It is to be noted that the late afternoon peak at

the three Rockwell sites appears to be at about the same time of day. As a consequence, the evidence of a pulse of ozone moving from north to south

along the valley axis is not particularly good. Anthropogenic activities along Highway 99 with associated urban influences may be a better source

for the late afternoon peak. The stong urban, local influence at Fresno is apparent from the

timing of the peak at 11-13 PST.

NOx peaks occur most frequently during the morning hours from mid­

night to 08 PST, reflecting the accumulation of combustion products during

the most stagnant period of the day.

2-22

Table 2.3.4

Average NMHC Concentrations July 1979 (06-09 PST)

(ppb)

Name Number of Samples Ethane

Stockton 9 11

Tracy 9 11

CSU 3 22

Fresno Riverside

2 20

Ethylene

Acetylene Propane Propylene Pro pad i ene

Isobutane

8

7 45

8 0

12

7

6 18 6 0 9

11

10

49 10 0 7

9

9 209

21 0

13

N-Butane 20 13 14 23

1-Butene 2-Butene y _____ .,L ----

1~openLctne

N-Pentane

1 4

.., ~ t::::J

13

1

3

17 8

1

3

24

16

0 5

61

39

Total 134 99 167 418

2-23

Table 2.3.5

Time of Maximum Concentration (PST) July 1979

0 NO Modesto (RI) 17-20 (13-16) 06-08 (20-23) Merced (RI) 16-20 (13-14) 00-07 Madera (RI) 11-14 (16-20) 00-06 (11-12) Turlock 12-14 ( 15-17) Modesto 14-17 05-07 Madera 14-17 FNO-CSU 11-13

2-24

2.4 Particulates

2.4.1 Total Particle Composition

Average total particle concentrations from the July 1979 intensive

are listed in Table 2.4.1. The major components on the average at aii three

sites were silicon, sulfate, and carbon with silicon tending to be the

largest, and sulfate and carbon concentrations being nearly equal. Average

concentrations of the crustal-like elements were highest at Merced and about

equal at Modesto and Madera. Average concentrations of the other elements

were not significantly different from one site to another. The average mass

concentration at Merced was about 20 percent higher than at the other sites.

Table 2.4.1

Average Total Particle (diameter <~ 20 µm) Concentrations Measured During July 1979

Component Modesto (14 Sameles) Merced Location (14 Sameles) Madera (7 Samples)

(,, n /m3)\t"' ;:, I '" I (% Mass) (µ g/m3) (% Mass) (µg/m3) (% Mass)

Mass 68.6 82.3 64.0 so=4-

9.5 13.8 8.9 10.8 7.0 10. 9

N03 3.1 4.5 2.7 3.3 2.4 - 3.8 +

NH,1·+

2.9 4.2 2.4 2.9 1.8 2.8

C 7.8 11.4 8.3 10.1 7.3 11.4

Al 3.5 5.1 4.8 5.8 3.9 6.1

Si 10 14.6 14 17.0 11 17.2

Cl 0.10 0.1 0.13 0.2 0.078 0.1

K 0.99 1.4 1.3 1.6 0.99 1.6

Ca 0.97 1.4 1.3 1.6 0.82 1. 3

Ti 0.19 0.03 0.26 0.3 0.21 0.3

V 0.019 2.6 0.020 0.02 0.018 0.03

Fe 1.8 0.02 2.6 3.2 2.1 3.3

Ni 0.011 0.04 0.0086 0.01 0.0078 0.01

Zn 0.030 0.03 0.035 0.04 0.020 0.03

Br 0.020 0.2 0.021 0.03 0.019 0.03 nL t'U " 1 ')u • .1..>

/'I , /'IVe .J.V

/'I ,v,i /'l /'lO'l

V• VJV /'l 1V••

Sum of Measured Comeonents 41.1 59.9 46.9 57.0 37.8 59.0

2-25

2.4.2 Source Contributions to Total Particle Concentration

Averages of the estimated contributions of the source types to total

particle samples for the July 1979 period are in Table 2.4.2. Emissions of

crustal-like materials accounted for the largest fraction of the mass.

Emissions from uncultivated land contributed substantially less material than

did emissions from cultivated land.

Emissions of crustal-like materials accounted for the largest fraction

of the mass. Emissions from uncultivated land contributed substantially less

material than did emissions from cultivated land.

Contributions of particles emitted directly by motor vehicles and oil

combustion were small, accounting for less than 1 percent of the mass at all

sites.

Ammonium sulfate contributed 9 to 15 percent of the average mass, while ammonium nitrate contributed 3 to 6 percent. Carbon from unidentified

sources accounted for about 10 percent of the average mass. The source types in the calculations, including excess carbon, accounted

for 96 to 102 percent of the average measured mass.

2-26

Table 2.4.2

Estimated Contributions of Source Types To Average Total Particle Mass During July 1979

Source Type Modesto 14 Samples)

Location Merced

14 Samples) Madera

(6 Samples) (µg/m3) (%) (µg/m3) (%) (µg/m3) (%)

Cultivated land 37.0 54.0 57.0 70.0 49.0 74.0

Uncultivated land 6.0 9.0 3.0 4.0

Motor vehicles (primary)* 0.4 0.6 0.4 0.5 0.3 0.5 Oil combustion (primary)** 0.2 0.3 0.2 0.2 0.2 0.3

(NH42 S04 10.0 15.0 8.0 10.0 6.0 9.0

(NH4) N03 4.0 6.0 3.0 4.0 3.0 5.0

Unidentified C 8.0 12.0 8.0 10.0 8.0 12.0

Sum 66.0 96.0 80.0 98.0 67.0 102.0 Measured Mass 69,0 82.0 66,0

* Includes only motor vehicle exhaust. Resuspended road dust is not

distinguishable from cultivated and uncultivated land. Conversion

of NOx emissions to nitrate is included with NH4 N03. ** Sulfate formed from S02 emissions and nitrate formed from NOx emissions

2-27

3. Tracer Summaries

3.1 Test 1 13-14 July 1979, Manteca Release 0700-1300 PDT)

3.1.1 Meteorology

General

The synoptic meteorology of the 13-14 July period was characterized by an extensive, flat high pressure region aloft over the southwestern states (Figure 3.1.1). Maximum heights at 500 mb were located just offshore of California inducing subsidence and warming of the air aloft over the region of interest. The warming and stabilization of the atmosphere is reflected in the 850 mb temperatures from Oakland and Vandenberg shown in

Figure 2.2.1. At the surface, a thermal trough was established over the Central Valley and southern desert resulting in an on-shore pressure gradient. Clear skies prevailed throughout the San Joaquin Valley. Visibilities were greater than 20 miles in the northern region of the valley, but decreased to about 10 miles in the southern portions. Surface temperatures were near normal for the time of year; maximum temperatures near 100°F were measured at all locations in the valley with Bakersfield reporting a high of 104°F on the afternoon of the 14th.

Transport Winds

Surface winds at the tracer release site are tabulated in Table 3.1.1 from the start of the release until midnight when the northwesterly flow ceased and winds became light and variable. The winds at the release site were persistent from the northwest at speeds ranging from 2-4 m/sec throughout the morning and afternoon. Streamlines of the airflow at 1000 ft-agl, con­structed from observed pibal winds, are depicted on Figures 3,1.2 through 3.1.6. At 0700 PDT on the 13th, a strong northwesterly flow was present on the west side, extending the entire length of the valley. At the southern end, a Fresno eddy had formed. Air was diverted and returned northward along the east flank of the valley. The formation of the eddy is a common occur­rence in the summer months and is described in more detail in Volume 2 of this study.

3-1

l­o 0..

U")

Cl

,-...

°'...... °'

>, r­:::,

-:,

M ......

V)

+-' ~

..c ~

u s.. Cl)

..c +-' ~ Cl) 3:

Cl) u .... ~ ~~-

......

....... M

Cl) ~ ::,

-~ C'l

LL.

I

Table 3.1.1

SURFACE WINDS AT MANTECA 13 JULY 1979

T;m,l"I, Wind (PDT) (m/s)

0700 290/2.4

0800 285/3.1

0900 295/4.2

1000 300/4.2

1100 300/3.8

1200 295/3.8

1300 300/3.6

1400 300/3.5

1500 300/3.3

1600 315/3.2

1700 305/2.9

1111"'-

., nnn. "'Inn'"' r:'!OUU ;)UU/ C.o :;J

1900 305/1.8

2000 270/1. 2

2100 290/1. 3

2200 ?QI; /1 . i:;---, .... -2300 005/0.6

3-3

-("

st.._,••c'!!f!f'•

. . . - - - --Figure 3.1.2 1000 Ft-agl Streamlines - 13 July 1979 (07 PDT)

3-4

...

U&.LI

0 C'...

-~., ! 1f' Ip,. . . . - - - --·- :; . . ' ... .-..

-, 4;·

. ;'

Figure 3.1.3 1000 Ft-agl Streamlines - 13 July 1979 (09 PDT)

3-5

~ N I

.,_, .. -_!_••=~!•~c::::~!-~tf_:__:___~_ c-,... - July 1979 (13 PDT)

- Figure 3.1. 4 1000 Ft-ag1 Streaml ,n. es - 13

3-6

...

HM.I

-~ • '! ! 'If If ,. . . . - - - --

I

Figure 3.1.5 1000 Ft-agl Streamlines - 13 July 1979 (19 PDT)

3-7

..,

sc ... ,~ft.........¥.....JJf..-.Jf ••

. . . . . - --Figure 3.1.6 1000 Ft-agl Streamlines - 14 July 1979 03 PDT)

3-8

By 0900 PDT (Figure 3.1.3) the southerly flow had extended as far

north as Modesto Reservoir so that the eddy dominated the entire valley.

This northward extension was unusual within the July observational period.

Generally, the eddy does not extend very much beyond Fresno. The eddy per­

sisted through most of the day (Figure 3.1.4) but was replaced by northwest

winds throughout the valley by 1900 PDT (Figure 3.1.5). By 0300 PDT (Figure

3.1.6) on July 14, however, another eddy had developed in the southern end

of the valley. This eddy continued to grow northward to encompass Fresno by

0900 but did not extend as far north as Modesto Reservoir.

The importance of the northward extension of the eddy on the morning

of July 13 was that the normal northwesterly flux of air entering the valley

was forced to the western side and was constricted in horizontal width.

Velocities were consequently increased considerably compared to the flow field

usually observed. This is shown dramatically in Figure 3.1.7 where a vertical

cross section of the flow field from Modesto Reservoir to Los Banos has been

constructed. Pibal winds were resolved into up and down-valley components at

construct the figure. Winds of Los

Banos at 500 mas a result of the constricted flow.

Under these flow conditions the tracer released from Manteca was di­

verted to the west side of the valley and was carried rapidly southward. The

eddy mechanism provides a means for redistributing the tracer throughout the

valley by the following day.

Mixing Heights

Mixing heights were determined from aircraft soundings by noting the

top of the pollutant or low-level turbulence layer. Table 3.1.2 gives the

mixing heights for all soundings made on July 13.

3-9

..-V)

E I E ~

~ :I: C!l ...... LU

w ~ I ..... 0

8 4

0

1500

/ ,/,;l m/1

1000

Southerlly Wind

INortherl:~ Wind 16

500 I- ,I ___,--4

;_//12

----·----....... ---~

_,____________ o

---------· I~

' 4 81/037

0

LOS BANOS TURLOCK I

MODESTO RES.

Figure 3.1.7 Vertical West-East Cross Section of Wind Component (m/s) (Positive Component into Valley) - 13 July 1979, 07 PDT

to Valley Axis

Table 3.1.2

AIRCRAFT MIXING HEIGHTS JULY 13, 1979

Time Location* Mixing Height (PDT) (m [above ground level]) 0603 Modesto Airport 210

0842 7 W Livingston 480

0916 15 E Modesto Airport 270

1648 Modesto Airport 570

1919 7 W Livingston 720

1951 15 E Modesto Airport 480

(* Distances in miles)

3.1.2 Air Quality

Regional Pollutant Levels

Maximum measured hourly average ozone concentrations for July 13 are shown in Figure 3.1.8. Within the valley, on the 13th, exceedances of the California ambient air quality standard were experienced only at Fresno and Bakersfield. However, in the Sierra Nevada, downwind from both urban sources, violations of the standard also occurred. On the 14th, widespread exceedances of the ozone standard were experienced in the northern and eastern

sections of the vaiiey. Oniy on the extreme west side did concentrations remain less than .10 ppm.

Maximum hourly concentrations for CO, S02 and NOx anywhere in the valley on July 13 are shown in Table 3.1.3. Maximum values for the Rockwell International sites are also included.

The effect of the southerly flow on the east side of the valley (Figure 3.1.3) on ozone concentrations is shown in Figure 3.1.9. This cross section across the valley between Los Banos and Modesto Reservoir was con­structed from aircraft soundings and horizontal traverses. Low levels of ozone aloft between Los Banos and Turlock) correspond to the northerly flow of air shown in Figure 3.1.7. On the eastern side of the valley, ozone concentrations were much higher in the southerly flow. The Fresno eddy therefore provides a mechanism for redistributing pollutant concentrations within the valley.

3-11

~.- I ---- --½- ,.:,:-,r_ -- ~--: -- ---- ------- --,., ~- • - -C. - .A.' 1 ,r - --' .

f \ -~r- . - . . I

!1 ~ "\. ! - l

--~\\ ~·. ~··, r\ \ \. 'hl\: "'--~=S --~ Cl

~ ~ ·i "1;,? '1,-tg J,. !, -;.<~ . , '. (-"--~_·_t ~\·'""·'"'" ~ J.~-~_;.~ - , -~ -,~

- ) '--1:! .· / ,~~.,, \) =;t' ., ~ \. c-1:-·,

L Ct:, ~:&. I"'~\:~ -D- J=-<- 6 .<\ .. ~ ~ ;, ~)-,

\. :[)::~:~"§'~ J_ ,-o:,c;:,, \ . '. ~~ 17:t \]'" ~ -\?>.,- f-,_, . ,,,.~~U'-" c. - • -. 0"1 :~-. '\....._, '-~__, .....~ '~ ~~ ..:.,~:o~~ir~J~< ~~\~ ~= ~~~-. ~~8 ~ -~;~~-J;] "\\ ·-,.. ,

l~, .~;.- ~ < - J --:::- ~· ,~ I

\1.:..""'--.~- ·.. r., ~- 11 ·. >--~ ~ \°'~ ' -,-.\ - , ' . - - --=- ~.\.. "" '

(~~~. L\\~ ~- "t/~ u·. - ~~\' 1

~~~~\t~t 5 ~ 7 J,~ ¼~ ~~\) ~ 1~~ 1 () ~ _ 12 \ L -"'° ;"'0./'-~ ~'\Q -,..__,.,.- , "~ ') ' . . ~J - ...:, .

.... --..

.

.

y -~, 2'_.Ji~--

- --,,_ ,-

,~- -'-~

~.. -........:

'

5

1

0- ~-~ '-<;-.._ - .... -

..1 J t._,-1,j - ~' '-

,,, -' .:,

'.

-·

;'...

\ ... ._ ~

\

.

N I

CJ ,o -..

Figure 3.1.8 Maximum Hourly Ozone Concentrations

3-12

(pphm) - 13 July 1979

1500

1000 ~

-1/1 E I

E ~

I-::c c.!)-w

I w I-' ::c w

500

90~

70/,/

-·---

' '~

-10/ .., _,o/ ,____ 80~

~ 81 / 038

O~ I I

LOS BANOS TURLOCK MODESTO RES.

Figure 3.1.9 Vertical West-East Cross Section of Ozone Concentrations (ppbMeasured Between 0646-0916 PDT - 13 July 1979

Table3.l.3

MAXIMUM HOURLY CONCENTRATIONS JULY 13, 1979

Parameter Location Maximum Value m

S02

S02

Fresno-01 i ve

Modesto

.02

•02

co Bakersfield 4.

NOx

S02

S02

NOx

NOX

NOx

Bakersfield

Modesto (RI) Merced (RI)

Modesto (RI)

Merced (RI)

Madera (RI)

.20

< • 01

< • 01

.02

•01

.01

Aircraft Sampling

Two sampling flights were made, one in the early morning (0603-0929

PDT), and again in the late afternoon (1648-2014 PDT). The sampling routes

were designed to define the distribution of air quality meteorological condi­

tions in a vertical cross section across the San Joaquin Valley. Traverses

at foui constant altitudes weie flown along a valley transect passing near

Turlock and Modesto Reservoir. Spirals were flown at locations roughly one­

third and two-thirds distance along the traverse route and over the Modesto

Airport. Figure 3.1.10 shows the sampling routes for both flights. Tables 3.1.4 and 3.1.5 give the general pollutant characteristics found on each part

of the sampling route.

In the morning the horizontal distribution at 1500, 3000 and 5000 ft

msl displayed the same general trends; ozone and bscat were greatest on the

east side of the valley, decreased to the center of the valley, then remained

relatively constant on the west side.

3-14

\

I 1 761: .,._~ ,., -·.. ~ .::~ ~66 l:

\\' 1.\.

-',~;t:•·te· ·,-~-

10 nm

SAMPLING ROUTES· 13 JULY 1979 P. M.

Figure 3.1.10 3-15

Table 3.1.4

AIR QUALITY MEASUREMENTS CARB SAN JOAQUIN JULY 13, 1979 SAMPLING

VALLEY PROJECT

Start Time (PDT) 0603

0646

0721

Location (Point)

1

2-3

3-2

03 Mean Max eeb eeb 79 103

74 101

85 111

bscat Mean Max x10-6m-l)

55 164

68 290

54 114

S02 Mean Max peb peb

1 2

0 1

0 1

NOx Mean Max peb peb

5 17

6 22

4 13

NO

Mean eeb

3

2

2

Max eeb

10

10 10

0803

0842 2-3 4

92

95

101

114

41

49

84

124 0

1 1

2

4

4

12

12

2

2

10

9

w I ..... °'

0901

0916 4-5 5

73

104

83

186 77

86

154

190

0

1

1

3

14

6

24

22

5

3

13

13

Table 3.1.5

AIR QUALITY MEASUREMENTS CARB SAN JOAQUIN JULY 13, 1979 SAMPLING

VALLEY PROJECT

Start Time PDT 1648

Loc,at ion (Point

1

03 Mean Max (eeb l (epb 106 139

bscat Mean Max (x10-6m-l

44 154

S02 Mean Max (eeb (eeb

1 2

NOx Mean Max (eeb (eeb 10 40

NO

Mean 1:eeb

5

Max (eeb -

17

1n4 2-3 138 157 75 150 1 1 10 29 3 14

1801 3-2 123 176 53 140 0 1 7 23 4 15

1839 2-3 145 192 62 146 1 2 7 22 3 14

1919 4 llO 141 57 150 0 1 9 44 5 34

1938 4-5 134 154 67 126 -1 0 9 22 3 10

1%1 5 154 188 73 138 1 3 10 23 53 17

w I ..... .....

The contrast between the eastern and western sides of the valley is

shown in Figures 3.1.11 and 3.1.12 which were taken to the west and east of

Highway 99, respectively (see Figure 3.1.10). Figure 3.1.12 shows a marked

ozone layer centered at 600 m (agl) with a peak concentration of .18 ppm. This

layer also exhibits high bscat values, indicating the aged nature of the pollutants. No such layer is shown in Figure 3.1.11 on the west side of the

valley.

High concentrations of ozone continued to be present aloft over the

eastern part of the valley during the afternoon. Figures 3.1.13 and 3.1.14

show soundings made at Points 1 and 4 (Figure 3.1.10) during the late afternoon.

The observed mixing height was about 500-600 m for both soundings with ozone

levels of .14 to .15 ppm within the mixing layer. On the east side of the

valley, however, (Figure 3.1.14) the ozone concentrations aloft reached a

maximum value of .18 ppm in contrast to .11 ppm over Point 1 (Figure 3.1.13).

Southeast winds within the upper ozone layer continued through 1300 PDT but

had shifted to north to northeast by the time of the sounding (Figure 3.1.14).

3-18

(flF,Pl T '- .:1~ lJ l ~•L;'J f)J Zl-lP~-R0 ~2:1~:Cl p t.,f;t 1.,

Ll ~I! 7 / I, I / ·l ~ CIJ TI ·v1_t< ,-)CJ ;,;f 4 LAHT~ILl(Ll~A~\: ot.~/ o

Tl~f: ~!4t: 1~ TtJ j!"ld:,::'6 ~lh. L~C~~C il~~.: le 1'1~,ll

-1r---------J--------10--------,o--------Ja--------41--------~0--------cc--------10--------do--------qo-------1ccl~Jdl ,,,,., l I 1

I ~~U I "'"" ll L T I 14701 .,x~ l r 1 l44LI I .,., B l T I

l-. l u I "NE* l T I.<~ LI I 8 D L T~~ .¢:

1 'j 'i r:i I l r ""' ,,u I.> lO I .:::,'4 ~ I) l T LEGEND 12-iu 1 11.=:: ll !l l T 12~( I ;;: J 0 l T FULL IL l( I ::: H L < r PARAMETER SCALE llMJ~ll:JC I <· X 'I C L T -I l 7 /J I .,;.; D L I (Turb) 10 cm •ta sec - 1 E* I 14u I N<X R L l T

O. S ppm z1 11 u I ,;i.;,:: 0 L L T (Oa)

lu80 I ~S* d L l T (NO, NOx) O. 2 ppm N,X l~~O 1 ;;._x h C l T

A I iJ ltl I [, l 1 (SOa) O. l ppm 5** ~ L 9'-lt; I S1H--A 1'! 0 L I 1

., 1) (b,.,.,) 10 x l~-~ m - Br ~60 I l T

I QJu I " d J l T o•- 100' C** (Temp) T T 'll)O I *X ~u l r

w u 117u I I\ ,J l T (Dew Pt) 0 • - 100' C D I "' *

f-J n ~4U I ¢:) ~ :) l T t •110 I *~ ~d .J l T'° ,~o I 5 ::ii:~ 1~ G l T,~., I ¢¢: t tl l T Figure 3.1.11 Aircraft Sounding - 13 July 1979 M Jl(J I N* * ,J l T

o9U I V d I) t l T M <,t,0 I ¢X h iJ L * s <,jU I *X d U l T E L oOO I h D l T E~"

.._j 10 I >* 0 !.) l I t ~4u I S* ll U l T t ~lu I S* 8 D l f r 4 ij(J I '-'N ll (J l t T 4 'i'l I "X 'l 0 l ff

:_i,:)4bJ I ti 11 T () ;;. tl I)19(1 I 'l T t

3oli I \'I\ ~ C l I f J3u I Ill 5 X l C l T f JOt; ,, :( ~I ~ C L r llu 1 ~ • M C l T l 4 G I S,,-.1)( ,1 C I L 10 I '.i I\ X a I) 1 T l lHu I .:.;, X o C l 'l I l I ~ ~ J( 0 l II\, "

~

llu I k C l T q., ' I X I\ G l r

• " <

t-hu I 'j•'lj r, 1/J

l 0- - - - - - - - -r:--- -- -- -- lo- -- - --- - L )- -- - - -- - 1 1l- -- - --- - ., -1-- - --- - - --11~ - - - - - -- - ti,~-- - - ---- 7ii- - - - - - - -11•1- - - --- -- - qi)------- I ,l)tl

Pt--1'\Ct "...:T -.~~ fl,ll :.CAL.:

(~fPLJ V~M ~l ~uf) :lJ 11-AP~-~~ 52:t4:L1 PAGc 2fJ

UI\ ff 7/11/ll .:icurf r1vt" fJ Cf• r c.., I t,, ... r INL,t LAH lg 11,ft:1•1 •\J\: 1H, 1\/ h ll•c: ~:1,,:11 T;: 'l:l4UI ~IN. G1~C1;f..,L lltV.: "' .,,,.~u

-10---------n--------10--------lo--------Jo--------4n--------~0--------oc--------1c--------aa--------Qo-------1cc l5h0 I f)j;¢ ·If. l 1 I l'>JLJ I 1,:..:~ \t Z T t l:OGLl I J1.¢: :¢1, l T I

I• 7u I C *<" l 1 I 1-.4•) I ... o,:* ~ l I I

1-.Jul "''* l 1;q.; I ,,x h l l

LEGENDl 3 '>L I s;.¢-" n C l T I J 1 t,, ~f ~ ur tt L 1 12. -JO M*t.; i F l r FULL I lt>C *~ F l T PARAMETER ~ lli!!!.Qb

, 1t.:3L: .k Ed 0~I (Turb) 10 cm 3/s sec-, E:1, •)LJI NS*~ D i T ,. .;.I J7u, G l 1 (Oa) 0, 5 ppm :z; I l '- e C T* l

(NO, NO•I 0. Z ppm IN,Xl ll~ ~1* EI:) L l T I OAu J;r ~ ri l T (SOa) 0. I ppm s 10~0 so BU l 1

l IUlO ~o 8 ~ l T 10 x 10-• m -, •

lb,.., I IS T -,qi) SNE~ H U L 1 I 'H'll.: • 0 l T (Temp) O"-IOO'C T T '<Ju ~ ~• 8 Ut l T

., X (Dew Pt) o•- IOO'C ID w u ~OU· ijUF l 1 I 0 ~70, ::: ¢ !J T~ l

0 t li,.O ;l1f .¢, ~ u L T N

Figure 3.1.12 Aircraft Sounding - 13 July 1979

.. bl'l S,N* ~ [) l T ]ijQ t-,p=: .. ;:: l T 75U ,.5, t • lT* 7l0• NS* du T l ,. t,-11) N:::Jl 0 R T l

5 obU NOf ll 1 T l l h JU ., st l, d T l

bO•J ~IS X E D b T l ~n ~"- Jl 0 >I Tt l ')'t(]1 ,;1 K [ltl T l f 5 111, I,; 5A D d T ,l E 4~UI N S X uu T / E • 5:J, IJ J" 5 X IT 4-'ll X d u fl ,qu .:;: X dD lT t 3~U 0 iiO l T F•

¢J 1~ X o/) l T t J0U \," X bO l T F ,.ll( X fl r c' 4,J' ~· .... • I) I ti L s Jf p I) l T ' l ,J ~ X tl fl f I.,.; ~ t. f) ' T I l ,', \, ,... .., JI; I) 1

1 'j I ,.. ,. •jf'

r11., " f( p;

- l d---------•,-· - --- --- 1•,--- - --- -2:~---- -- -- j 1;-- -- -- -- <.t'J---- - - -- .. ,1- - - - - - --n-J-- - - - --- Jr!-- -- --- - 1 >- --·-- -- -Q1J------- JLC 1>1 f<LI f'. f l r:: ~ l..1.l ',t,~t,

(t)r:µt T .ih~ Cl il-'1_,,) 1;3 !l-APH-1)0 )~:22:J4 P AG t

UVfS P(lt,,Il'A T 7/13/IY ~ ( lj f I

LA~TKIGCt/~A~~; hr)q/ Tl~r: lb:47:4U re 11: ,:Ll ~I•~• GMCL~I; tlfV.: z9 ~,~,u

-1a---------.1--------1~--------20--------io--------4.i--------~o--------•o--------1a--------~o--------qo-------1cc 1 ') 1. (J I f;<•NHC L T Cl l :-,r:1, I <•hi l T Cl 1., 7,J I <•N*• l T Cl

l '• 40 "'''ti JC t l T CI 14 Ill * Cr. * l T Cl 11~0 * 0 e f l T CJ l j "l(J I~ X :.i, * l l CJ l J. ?t; t l T CI l /Q~l f]~ I: l CI I LoC ~ ;~:f l I LEGEND CI l .! HJ ~~•Cijt T Cl l l '1 e, S 00i L T FULL CI I l 7 u ~ c~ l T PARAMETER ~!!.,. CI~ I 14 J ~. ~ r. l I CI

(Turb) 10 cm •1., sec-, EI l l J 'l -~iC Ml( l I CI' Iv P .J ~ ~. :.;. X f l I (0:,,) 0. 5 ppm z CI lO~U *X l T CI

A 10/U :. 1,J;. t l T (NO, N01) a. 2 ppm N,X CI L '1\.ilij ~N C.* i. l T CI

(502 ) 0.1 ppm s T Yn1J s * a l T CI I ~~.I \C¥k l T IOxlO-•m- 1 B CJCbscat)I -I 1)1..1 ~,.:: t,.: Li l T CIw

I u 1170 ~tt\; !,:: t· l T (Temp) o·-1oo•c T CIN ..... r, ~4C: ~u :::x f l T CI

(Dew Pt) 0 • - 100 • C Dt dlO t l T CiS O "" 7PO ,I*• F T CI(CN) 100 x IOa cm ·a

-, , (.1 Cs tl T CI.. *" ,. 1ld '., N bJCl) F i. T CI c:,QJ N -~ Dl< LET CI f)b(I DX Figure 3.1.13 Aircraft Sounding - 13 July 1979 CI* *

5- o1U :, N H D X l H CJ t,r,,::L "b DX l tl CI i.; 7t) '> " 'I * f I T CI - ~-)

,,.. r, 8 O,X I' L T CJ ., l il 1;"" ti ex f l T CJ 4 ~ ~J •; " 11 ex l T (J

4':)lJ Nt11)X C l T~ Cl ... ~d s t l T CI* 3YC I: T\ "" l CJ'" •i * 36d " ,, n f l T CJ j :hJ ,) ~ ti ( 0 t l T CI 30l) s ~ ~ti LJ l T CI '1,; \ ~X d 0 I' l T CI l¼L \ ~A M I) f l T CI ,10 f\ J. I, 0 L Tt <I l2L r, ~-,~ l T CJ l~J '> ~ ~11 Q I r I CI 11~ ~ ~ X ij 11 l T CI ~J l\j i~ "C l f t CI l1L I ~ l l f CJ l<i a < l I f Cl

- i o - - - - - - - - - 1i •- - - - - - - - 1 8 - - - - - - - - .: o - - - - - - - - :.. n - - - - - - - - 4. l - - - - - - - - '=' t, - - - - - - - - o ·1 - - - - - - - - 7 o - - - - - - - - - - - - - - - ~ o - - - - - - - Ju Cll-J -

Pt~Ct~J ~r ~~LL 'l(~l~

C"i-:._)t 1 vFr l)l "'1;_,) ·)J I l-1\1.lfJ-dO ~:d: -?/: j4 ,,. AG c 2()

c 4 1 • r, 1,1n I'<- CUT t 1;y,_u P~tr.f '1 LA,clklU(~/~A)\; Oo4/ 8 1 I.• I , I Q : 'i I : 1 4 T,J , 0 : •, : 1 I ~I~. ~~(L~C ~Ltv.: ,.7 ~,~s1.1

-1a---------o--------1,>--------JJ--------iil--------4:1--------so--------6a--------10--------eo--------~o-------1co 1 ~-"i,'J I •'•D~ fT l Cl L ':> '0 SX N Dti I ! CI I -:.no ,.x i;g t Cl l ~ 7'> N~ XOti ~ ! CI 14·• 0 l Cl l4lu "' *. ' ~ " * l l Cl 13,u X 'i I\ < f T l CILEGENDl .i ""J <_;r.., :;,u T)I L C l _;,(.J 'ii\ I q r l C l29u ~~ ') .A t'-' T l FULL

C l t ,, •J ,, ;( PARAMETER ~MBOLV•' l ~ C 1<1~ ls "" (Turb) 10 cm "la sec-, E C 1/l)C "'s • l C I I 7 0 1\5 X fl-' l (Oa) 0. 5 ppm z C l l•+o l* X C(NO, NOx) 0. 2 ppm N,XI I I u s~ JI. * ~ T l C l C l~l.) T* X l o (SO3 ) 0. I ppm s C l L •:;u S~ X F till T C'l !OxlO-•m-1

L l<l./0 )~ I( .:. ~ 0 T l (b,...) B C T '':J s. ~ X t I~~ l I C/tl') ;11. • * u l (Temp) 0° - I00"C T

C C

w I 1 4·\u X ¢ LI l C N ,,oo * (Dew Pt) o·-1oo·c D

u s I: 'I (; T lN " X C 1) 8 7U SN , I: !l C T l 100 x 10• cm-• C C

• (CN)t htfU 51, I: ~ C T l C n Lu I~ 5 X E H IJ T L C 7110 I( '\ :;:. Tl hU " s ... u,c

C

"' no :,N ,. C LT

¢ Figure 3.1.14 Aircraft Sounding - 13 July 1979 C

C ,.~ tJ9l) i-s • ,. 0 C ,.s bt,1) s 11. r ,. D C l t,'IJ 'I r.~ x ll D LT Cl

tiOo * E *• 0 l T CI ~l() St, ~ Xll C l T CI ')(t') '\ " • Xd 0 l T CI -' l. (j ~ * ll I D l T CI <+itu S "E 8X C L T CI .. 'i,J ~ Xr e L T CI 4lU S~ ~~ Ll ' l T CI jtl.J ~ 11. Ob C l T CI :1ufJ ')f',jJ( il Tl CI i 1

: l 5"' ;'. ~ I) l T Cl j/lu I T CI ,' 70 ~ '). ·l IJ l Cl

') I r :1 )( U T

,- ''°' L

, CI 1111 ) I\ t iJ X U L T CI I ·I 'J N ,:, "I( r~

/ "' J

l CI l •, u " t [) I CI l ;, l " ' I 1 (I

_, II,!\ \ u T (I', I T (I",

-l')---------J--------10--------L 1)--------,0--------4;)--------~il--------b'l--------1·1--------hf)--------y 1)-------1cc ~cf'(li~T U~ ~Ull \CAL~

3.1.3 Tracer Test 1

Release Location: Manteca, San Joaquin County

Time and Date: 0700-1300 POT, 7/13/79

Amount: 104 pounds of SF6 per hour

Release conducted during northwesterly winds of between 2 and 4 mps.

Throughout the release day, winds on the western side of the valley were

northerly while an opposing southerly flow was noted on the eastern side of the

valley.

Initial transport southward

During Automobile Traverse 1-1, beginning about 0900 PDT, a maximum SF6

concentration of about 320 PPT (450 PPT/lb-mole of SF6 released/hr) was

detected near Modesto along Hwy 132. 179 PPT of SF6 was detected during the

0900-1000 PDT automatic hourly-averaged sample at Modesto (see Figure 3.1.15).

Modesto I ies about 16 miles south of the release site thus the average tracer

transport speed was at least 8 miles/hr (3.5 mpsl. This compares favorably

with the 2-4 mps surface winds measured at the release site between 0700 and

0900 PDT. Automobile Traverses 1-2, 1-4, 1-5 and 1-8 al I passed through

Modesto on Hwy 132. The tracer plume retained the structure found during

Traverse 1-1 until about 1400-1500 PDT, about 1-2 hours after the end of the

release. At the Modesto hourly-averaged sampler, 250 +/- 30 PPT ( 350

PPT/lb-mole SF6 released/hr) was detected between 1000 and 1400 PDT. Only 117

PPT, however, was detected during the 1400-1500 PDT sample.

Continued southward transport during afternoon

The tracer was also detected further downwind during a number of

automobi ie traverses. During Automobiie Traverse 1-6, a maximum concentration

of 240 PPT (340 PPT/lb-mole SF6 released/hr) was detected along Rd J17. During

Traverse 1-9, 124 PPT of SF6 (174 PPT/lb-mole SF6 released/hr) was detected

along Hwy 140, west of Merced. During Traverse 1-12, 161 PPT (226 PPT/lb-mole

SF6 released/hr) was detected along Hwy 140 and concentrations as high as 116

3-23

SJV-1 7/13/79 - 7/15/79

300 1 Jfhn, MODESTO 0 I+ I I I I I I I I I I I I I I I I I I I I I I I I I I I+ I 1 , I I , I l I I I

300 rI LIVINGSTON 0 I I I1fil+u I I I I I I I I I I I I 1 , I I LJ I I I ~ I ' I , I+ I I I , I I I I I

100 Ii DOS PALOS 0 1 I 1 1 I~ L__J I I 1 1 I • hi I H 1 1 I 1 1 I 1 • I 1 • I H I t I I 1 • I

100 r TRANQUILITY 0 I I I 11 1 I L I I 1 +J1::6 1 I L L b-t-t I f r:::6--i L-I L I L I lx:x1xlx1r1xlx1X1xlzi'+ I

100 I. MADERA 0 1 I 1 1 11 t .p ,.LrwJ--u I 1 1 I I K---Lt J 1 1 I 1 1 I : , I 1 1 l 1 1 I H +1 • I

100 r-' . O'NEALS

0 I , 1 11 1 I 1 : ,r1xixlwx1rlx1X1rlx1X1xl I t I 1 1 l 1 ' L L l I t+A L I 1 1 I =4 I I I 100 r

MARIPOSA 0 I t L I 1 +I H I tM:I I l L l L 1ylxw•xlx1,1xlxwxb:x1 Li I I c I l t t I 1 +I L L I L l Il­

o... 0..

r, (D LL lJ) LJ

100 r (It 1.1. d , w , , , J .J , , 1I , L, bhr.l , , 1 , , 1 , , 1w .., T

100 r-1

0 I 1 •+LJ 1,, 1,, L, 1,, L, b-w ix-I, 1, 1 I 1 1 I u 100 r

_i,,l,c_JL_,. ,,l,..J,,1,,1,,1,,1,,1,,1

PATTERSON4 L 1 I I I I • 1 , • 1

GUSTINE Li ,4 1 , I,, I,, 1

MERCED . 1

IQ

100 r , CHOWCHILLA

0 I I I 1, I I+ I I I t::H::t L I 1 , ' I I I I , Lj H I Htttt! I I I ' ' I ' ' I+ I I ' I I 100 r FRESNO

0 j 1 1 I 1 1 I 1 1 I • 4I • '= k..J I L I I H 1 1 6 1 wI I 1 1ttlw.ttttttlx-tutl,,.11:ttlw+t+ I 100 r OAKDALE

0 I+1 J • 1 l , 1 I I H 1 • I 1 1 I 1 1 I 1 1 I Ht'ttl,,.HtHtl,,.Ht:tltk:HtHti.+ 1 I 1 1 I 1 1 I 1 • I 100 r-

:I I I

0 Lft I I I I f

6 9 12

RELEASE RELEASE

MODESTO RESERVI I I I I I I • I I I- I I I

I I I I hi I I I I I I Ld I I I I I J 1 I I I I I I I+ I I I I I I I I I I I 15 18 21 24 3 6 9 12 15 18 21 24 3 6

PACIFIC DAYLIGHT TIME

LOCATION: 623 LBS SF6 AT MANTECA TIME, 0700-1300 PDT, 7/13/79

Figure 3.1.15

• INDICATES MISSING DATA ARROliS INDICATE BOUNDS OF StMPLING PERIOD

3-24

----

SJV

1

.. '

'

:~ ).' I .~Art,~

j,TA,"•,HS.'­,,;,.,,,:«:.,,,.

',

"-4,0'f'AMl!r. \ il,.J,,111/1.

\ ~> - ' A '-,

Figure 3,1.16

* INDICATES SAMPLER LOCATIONS ((@), IS THE RELEASE SI TE 3-25 ~/

PPT (163 PPT/lb-mole SF6 released/hr) were detected along Hwy 152, west of

Chowchilla. During Traverse 1-13, SF6 concentrations of about 90 PPT (125

PPT/lb-mole released/hr) were detected over a wide zone along Hwy 180, west of

Fresno. The locations of the maximum concentrations detected during these

traverses indicated that the tracer was initially transported southeasterly

along Hwy 99. Along Hwy's 140, 152 and 180, however, the plume appeared to

have shifted towards the west. This may have been due to the action of the

southerly flow in evidence on the eastern half of the San Joaquin Valley.

Because of the strength of the southerly flow on the eastern side of the

valley, the northerly flow on the western side may have been diverted more

towards the west.

Further evidence of the shift westward of the SF6 can be found in the

hourly averaged data. Al I hourly-averaged data collected is included in Figure

3.1.15. SF6 was detected at Livingston, along Hwy 99, between 1000 and 1100

PDT. Livingston lies about 40 miles south of Manteca, suggesting a mean

transport speed of about 10-13 miles/hr (4.4-6 mps). SF6 concentrations above

15 PPT were first detected at Dos Palos, about 70 miles south of the release

site and 25 miles west of Chowchi I la, during the 1500-1600 PDT sample,

corresponding to a mean transport speed of about 8.8 miles/hr (3.9 mps).

Finally, SF6 was detected at Tranqui I ity, about 100 miles south of Manteca and

25 miles west of Fresno, during the 1700-1800 sample which corresponds to a

mean transport speed of 10 miles/hr (4.4 mps). Maximum hourly-averaged tracer

concentrations of 162 PPT (228 PPT/lb-mole of SF6 released per hour), 92 PPT

(129 PPT/lb-mole released/hr) and 54 PPT (76 PPT/lb-mole released/hr) were

detected at Livingston, Dos Palos and Tranquility, respectively. The maximum

concentrations detected at these fixed sampling sites agreed favorably with the

maximum concentrations detected during corresponding automobile traverses.

Note that essentially no SF6 was detected at sites along Hwy 99, south of

Livingston, or In the foothi I Is on the western slope of the Sierra Nevada

Mountains. Again, this is consistent with the apparent decoupling between air

flow on the west and east sides of the San Joaquin Valley:

3-26

Comparison of plume dispersion to Gaussian plume model

The tracer was apparently transported by strong, unidirectional winds

suggesting that the tracer transport and dispersion might be accurately modeled

via the Gaussian plume model. As shown in Figure 3.1.17, the concentration

profiles encountered during most traverses were essentially Gaussian in shape.

The standard deviation in concentration was estimated to be about 1.81 +/- 0.26

miles for traverses along Hwy 132 through Modesto. The average trajectory from

Manteca to the plume centerline at Modesto meets Hwy 132 at an angle of about

45 deg. Thus the crosswind standard deviation in concentration was about

1.81*sin(45 degl=l .3 miles=2.1 km. Thus the horizontal dispersion of the

tracer at this distance downwind corresponded to Pasquil I-Gifford stabi I ity

class C. The estimated crosswind standard deviations in concentration along

other automobile traverse routes are included in Figure 3.1 .18. The

Pasqui I I-Gifford Stabi I ity Class curves presented are extrapolations of the

curves presented in Turner (1970r". The horizontal dispersion is consistent

with Pasqui I I-Gifford Stabi I ity Class C or D for distances less than 100 km

downwind of the source. The deviation at greater distances may be due to

variations in wind speed or atmospheric stab ii ity that occurred near nightfal I.

Also included in Figure 3.1.18 is the vertical standard deviations in

concentrations estimated from the crosswind integrated surface concentrations

(see Turner, 1970). The data shows no significant tendency to increase with

distance downwind of the source, suggesting that the tracer was wel I-mixed over

an essentially constant height. The vertical standard deviation is 80% of the

mixing height. Based on the traverses along Hwy's 140 and 152, the maximum

mixing height was about 400/.8=500m or about 1640 ft.

Carryover into subsequent day

Low levels of SF6 ((5-10 PPTl were detected throughout the San Joaquin

Vai iey north and east of Fresno on the day fol lowing the release. Due to the

I imitations of the SF6 measurement technique, it is not possible to

quantitatively estimate the amount of carryover into this day.

* Turner, B. 1970: Workbook of Atmospheric Dispersion Estimates, PHS Publ. No. 999-AD-26, 84 pp.

3-27

TRAVERSES SJV-1 '"'

HWY 132 TRAVERSE 1-5 1235-1316 PDT:1ill~k. ,,,,,,, """;;; -----DESTO

~ \

~RAV 1-9 1428-1518 PDT

I ii ii II II II lV:::> MERCED

~'

'"',

\ -,, TRAY 1-12 1688-1814 PDT

',,

HWY !~ ,,0!11Uli1111il!Ui1,

\ \

\

AVE 7

FRESNO

T 3SS PPT 1

Figure 3.1.17

3-28 NORTHERN SJV SCALE - le 208000

SJV-1 GAUSSIAN COMPARISON 100

X ~

... IJ. LL UI 0 u z 0 1-4 CJ') 10 a:: w ll. (/) 1-4

C

. N 1-4

0:: 0 :I:

1

D

10000 r

A 8 C

X

... IJ. IJ. UI 0 1000LI

z Q0 C 1-4 (/) E0a:: w ll. (/) F 1-4 100C

t-• 0:: UI >

10 I I I I I I I I I I I

10 100 1000

DOWNWIND DISTANCE. KM Figure 3.1.18

o DATA TAKEN AFTER END OF RELEASE 3-29

Summary

During this experiment, the tracer was released at the northern mouth of

the San Joaquin Valley. In this vicinity, a northerly flow (blowing into the

val leyl persists essentially 24 hours per day during the surTY11er. Pollutants

generated in the San Francisco Bay Area and the California Delta can be

transported into the San Joaquin Valley through this region.

During this test, the tracer was released during the morning. Typically,

the atmosphere is more stable during the morning than during the afternoon. On

the day of the test, however, the wind flow patterns detected in the valley

suggested more unstable conditions than might normally be expected. High wind

speeds were detected, for example, at Los Banos (16 mps at 0700, 1000 ft

elevation). In addition, southerly winds were found on the entire eastern haif

of the valley while strong westerly winds were detected on the western side.

At one time during the day, the velocity shear between the western and eastern

sides reached as high as 24 mps. These conditions led to dispersal of the

tracer at a somewhat higher rate than might be expected from meteorological

data collected only at the release site.

The tracer was initially transported along Hwy 99. The tracer was then

transported down the lowest part of the valley, along the San Joaquin River on

the western side. There was no evidence of the tracer being influenced by the

upslope winds along the Sierra Nevada on the east side of the valley. An

overview of the tracer transport path is shown in Figure 3.1.19. Since the

tracer tagging pollutants from the San Francisco Bay Area and the California

Delta was preferentially transported down the western half of the valley, and

since higher concentrations of ozone and other pollutants were found on the

eastern side of the valley, the Bay Area apparently had little impact on

pollutants in the San Joaquin Valley on this day.

The concentration profiles downwind of the release site were essentially

Gaussian in shape. The horizontal dispersion of the tracer corresponded to the

disperion expected for Pasquil I-Gifford Stab ii Ity Class C or D. This

comparison to the Gaussian plume model was based on 12 different traverses

along 5 different routes at various distances downwind. From automobile

traverse data it was possible to estimate that the tracer was essentially

wel I-mixed vertically to a height of about 1650 ft.

3-30

w I w....

@ ,.-,,;'

'\ (v

! JEl.mI Sil£ - rwm:CA I

IC/IllIO 0 10 10

'1111.U

~

~

&J~'

IO<>c,

\_~"--( ~

ARROW POINT INDICATES OBSERVED TRACER LOCATIONS NUMBERS REFER TO HOURS AFTER RELEASE START (0700 PDT., 7/16/79)

Figure 3.1.19

Low concentrations of the tracer were detected over a wide area in the

central and northern valley on the day after the release. At least some of the

tracer released on the previous day was redistributed throughout the northern

valley by the night and early morning wind flow patterns.

3-32

3.2 Test 2 16-17 July 1979, Manteca Release (1300-1900 PDT)

3.2.1 Meteorology

General

and was

states.

The syn

characterized

As can

optic meteorology of 16-17 July is depicted

by a regional high pressure aloft over

be seen from Figure 2.2.1, this period was

in Figure 3.2.1

the western

th~ beginning of

a significant warming trend aloft which was to continue for several days.

At the surface a thermal trough was established over the California interior

which created onshore pressure gradients. Skies were clear within the

valley with only a few scattered cumulus reported over the higher mountains.

Visibilities were reported down to 7-10 miles in the central and southern

portions of the valley in the afternoon. Stockton reported restricted

visibilities due to smoke on the morning of the 16th, but conditions im­

proved later in the day. Surface temperatures were above normal in the

valley for the time of the year. On the 17th, Fresno reported a high

reading of 107°F and Bakersfield 109°F.

Transport Winds

Surface winds from the tracer release site at Manteca during the

release period are summarized in Table 3,2,1. Winds were from the north­

west at 2-3 misec. The regional flows in the San Joaquin Valley during

the experimental period have been determined from the 1000 ft streamlines

and are depicted on Figures 3.2.2 through 3.2.4. At the start of the

tracer release (1300 PDT), the flow was generally from the northwest at

speeds of 2-3 m/sec. In the central portion of the valley, the eddy which had been present during the early morning had drifted eastward, but the

flow on the west side was still being diverted westward by the eddy in­

fluence. On the west side, northwest streamlines continued the length of

the valley. This basic flow pattern continued until the 1900 PDT obser­

vations, when the flow became northwest throughout the valley at speeds

ranging from 3-6 m/sec (Figure 3.2.3). The same general flow pattern

continued for the following several hours, although wind speeds increased

3-33

,-:

:,...., ;:, ....

f­Cl 0..

LO 0

.....°'

....°'

V, .µ I,..

..r:"' u I,... CIJ

..r:

.µ

:;: "'CIJ

CIJ u

'+-"' 1,... ::,

V')

..... N . M

CIJ I,.. ::, C'\

LI..

Table 3.2.1

SURFACE WINDS AT MANTECA 16 JULY 1979

Time Wind (PDT) (m/s) 1300 305/2.2 1400 300/2.7

1500 305/3.0

1600 325/2.7 1700 310/2.7 1800 305/2.8

1900 325/2.3 •

to a maximum (6-11 m/sec) at 2300 PDT. At 0300 PDT on the following morning, an eddy again formed in the southern portion of the valley and continued to

develop, reaching a maximum between 0900 and 1200 PDT (Figure 3.2.4). By 1700 PDT the flow was generally from the northwest again. The vertical and temporal characteristics of the winds aloft can be characterized by the time-height cross section of the winds above Turlock given on Figure 3.2.5. The pibal winds have been resolved into components parallel to the valley axis which are shown in the cross section. The northwest flow was relatively shallow during the tracer release extending only through a 2000 ft layer above the ground. Flow with a southerly component prevailed above. A moder­ate to strong flow transporting air south into the valley persisted at low levels throughout the experimental period. Maximum speeds within the northwest flow of over 10 m/s were observed late in the evening of the 16th.

Mixing Heights

Mixing heights were determined from aircraft soundings by noting the top of the pollutant and/or turbulence layer. Table 3.2.2 gives the mixing layer depths for July 16-17. As indicated, there is a marked tendency for higher mixing depths at the edge of the valley compared to the center.

3-35

....

C'

... .-;· ' .. • . ....

.......

Figure 3.2.2 1000 Ft-agl Streamlines - 16 July 1979 (13 PDT)

3-36

(·

.... .,, C",-,

C"

•,14, • C '! ! 1f f la ... -· - - --

- . r ,...

1a. ..... -·-....... . .. ... ., . , ..

--.... ~-

f

Figure 3.2.3 1000 Ft-agl Streamlines - 16 July 1979 (19 PDT)

3-37

....

.. ·- .... . . ..... au,1..1

••&'!!!IP'• ... . --·

. . . - - - -- .." ,. Figure 3.2.4 1000 Ft-agl Streamlines - 17 July 1979 09 PDT)

3-38

2817

2547

2277

2007 ~

V'I E I

E 1737

I-:c <.!J ...... 1467 w :c

w 1197 I w I.D

923 ......," I

639 '~~

-8 -6

.._)

-6 -4

l ~

2

----o -2-.. ."-... J I ~

2 _____. 340

2-4 -2

,,,,,,,----------------......__...,... _2

f 8 ---.........._fr-~\_---·.:__) __,_ J .__, 4 b 6---:---__...,- 4 ~6"""~8

13 15 l 7 19 21 23 l 3 5 7 9 11 13 15 l 7 19 15

HOUR (PDT) 11/059

Figure 3.2.5 Component Wind (m/s) From Turlock -(Positive Represents Upvalley Flow)

16 July 1979

Table 3.2.2

AIRCRAFT MIXING JULY 16-17,

HEIGHTS 1979

Time (PDT)

July 16

1653 1730

Location*

Modesto Airport Modesto Reservoir

Mixing Height (m [above ground level])

600 770

1755 1851

Foothills Patterson

(30 ENE Modesto) 990 970

1958 July 17

0541 0618

Modesto Airport

Modesto Airport Modesto Reservoir

150

120 80

0642 0732

Foothills Patterson

(30 ENE Modesto) 300 120

(* Distances in mil es)

3.2.2 Air Quality

Regional Pollutant Levels

Maximum hourly ozone concentrations throughout the valley on July 16 are shown in Figure 3.2.6. A number of exceedances were observed in the valley. The highest hourly average recorded was at Bakersfield (.14 ppm). On the following day, a maximum of .17 ppm was observed at Fresno and ex­ceedances occurred at Whitaker's Forest and at Miracle Hot Springs, indi­cating the upslope transport of ozone and precursors from the valley floor.

Maximum hourly concentrations for CO, SOz and NOx anywhere in the valley on July 16 are given in Table 3.2.3. Also shown are the maximum values recorded at the Rockwell International vans for the day.

Aircraft Sampling

Sampling was conducted late on the afternoon of the 16th (1650-2013 PDT) and again on the morning of the 17th (0540-0850 PDT) to determine the flux of pollutants into the San Joaquin Valley. The sampling pattern was

3-40

(

(- Figure 3.2.6 Maximum Hourly Ozone Concentrations (pphm) - 16 July 1979

3-41

Table 3.2.3

MAXIMUM HOURLY CONCENTRATIONS JULY 16, 1979

Parameter Location Maximum Value m

S02 Bakersfield .02 co Fresno-Olive 3.

co Bakersfield 3.

NOx Bakersfield .19

S02 Modesto (RI) < • 01

S02 Merced (RI) < .01

NOx Modesto (RI) .01

NOx Merced (RI) .01

NOx Madera (RI) .02

similar on both days. The flight pattern consisted of a vertical cross section of the valley with two constant altitude traverses and a series of spirals on

a line roughly perpendiclar to the valley axis between Modesto and Turlock.

Spirals were flown over the Modesto Airport at the beginning and ending of

sampling to document any temporal changes. Figure 3.2.7 shows the sampling

routes carried out on July 16 and 17. Tables 3.2.4 and 3,2,5 give the general

pollutant characteristics observed on the flights.

The horizontal distribution of ozone and bscat was reversed from the

sampling on the 13th. The greater pollution burden was found on the west side

of the valley. At 4000 ft-msl (1919 PDT) ozone concentrations averaging over

.10 ppm on the west side decreased to under .05 ppm on the east end of the traverse, Gradients were not as great on the 1500 ft-msl traverse, averaging

.13 ppm on the west side as opposed to .11-.12 ppm on the east side. Maximum concentrations of ozone in excess of .18 ppm were measured over Patterson on

the west side as opposed to less than .14 ppm on the east side. Figures 3.2.8 to 3.2.12 show the aircraft soundings taken during the

late afternoon of July 16. Figure 3.2.8 is a sounding over Modesto Airport.

The mixed layer extends to about 610 m-msl but extensive ozone and bscat exist

3-42

• •;

"""' - ,.... •. - _....___ .

1----S_c_a_l_e__--1( ., :~/: 1 0 nm_ . _ ·-· . ..n, . - · _

SAMPLING ROUTES 16 JULY 1979

Figure 3.2.7 3-43

Table 3.2.4

AIR QUALITY MEASUREMENTS CARB SAN JOAQUIN VALLEY JULY 16, 1979 SAMPLING

PROJECT

Start Time PDT)

Loc:ation (Point)

03 Mean Max (ppb) (ppb)

hscat Mean Max (x10-6m-l)

S02 Mean Max (ppb) (ppb_) -

NOx Mean Max (ppbL (ppb_)_

NO

Mean Max' . __J£P.b) __ Jppb)

0653 l 79 130 80 210 1 2

1730 '),_ 84 138 64 156 1 1

1755 3 99 143 76 158 0 1

1817 4-5 124 155 112 190 1 2 1851 6 124 185 93 184 1 3

w 1919 6-4 80 111 81 152 1 1 I .p. .p. 1959 l 103 168 109 192 1 1

Table 3.2.5

AIR QUALITY MEASUREMENTS CA.RB SAN JOAQUIN JULY 17, 1979 SAMPLING

VALLEY PROJECT

Start Time (PDT

Location (Poii nt)

03

Mean Max (ppb) (ppb)

bscat

Mean Max (x10-6m-l)

SD2

Mean Max (ppb) (ppb)

NDx

Mean Max (ppb) (ppb)

NO

Mean (ppb)

Max (ppb)

0541 1 63 120 76 186 1 2

0618 2 67 105 68 138 1 2

0642'. 3 63 105 64 136 1 3

0706 4-6 73 92 79 144 0 1

0733 6 52 119 56 188 1 11

07511 6- 1i 34 47 30 64 0 1 w I

.p. 082? 4-6 79 108 75 138 1 1

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Figure 3.2.8 Aircraft Sounding - 16 July 1979

.. ~ I) s I) R l E T 4s,o s ('I

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w ,.,Jo (Oa) 0. 5 ppm zu D S C l T .;,. T I

D ll 70 t cl....., * (NO, NOxl 0. Z ppm N,Xh4U s t [J I! L T ,olu t J b l T (SO1 ) 0.1 ppm s 7Ru :, f) l:Jl:: l T

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t,IJO \, * ,. l E T

,10 s Qij ll T Figure 3.2.9 Aircraft Sounding - 16 July 1979 ~41) s * b l T ~lu s n~ F l T <,80 s ~ f l T 450 s HU E l T

*4l0 ; < l T ;G10 s t l T*

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T Figure 3.2.10 Aircraft Sounding - 16 July 1979

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LFigurel

3.2.11 Aircraft Sounding - 16 July 1979 ••RU s 1: o e 1 l ,:. ".,t) 5 t * T l ·~ l u s F 1'.ll T Z J~u s T l :H1LI s rlU E .. l lU '

,,o l1 301) s i·i* lT < lu s d* /T l4~ '., * ll l T dO ':, t lU l T I ij iJ s [ l)c, l 1 J. 'jlJ ':, L l T u~ s I T

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(,1)t=VL T \.t-=K -Jl ,,1L )j Jl-APR-c 1' Slt:22,:ll PAGI 17

cAT 7/l~/7"'1 .<Cult: '1V•k ~CINI I (.AU';1<fll([/Ot1:-:,I._;: t1"1J A

T J r,t,i ; 1 q: '5 d: _-, 7 rq IO: 1 !.- : La ~,~. G~CO~C flr~.: ?Y ~(~-ill

-l~---------u--------lJ--------zo--------,o--------41)--------~G--------6C--------7C--------e~--------qa-------lOC l',h) I s E C e (. ' l r I ':,ill) I ); l U d C i 1 I l ~ 7 •J I ~ l 11 ll C l r I 1•40 I S f O ~ l i T I I • lo I 'i lJf e l l T I 1 ~P,J 1 -> .=u .,, T I H,~,l I > t G c ( l T I I ·1,20 I -; II '1 II IC T It ·>o 'i f i.) " L I libC s ,, C e L I T 12 Iv Sf- [ 1 ( l T I i"l 0 '.iF L e \. I T 1110 \f l) ~( l I l 40 ',[ I) " C l T I 1 I •J sc L tll L T LEGEND l 011 t, '>f (; e l l T

~

l

I O'>ll l : 7 U

qq()

s s s

t t

fj( 1i

C C.ti Gil (.

l l

l

T T I

PARAMETER FULL SCALE ~YMBOL

T "lllli <; IJ ~ C l r (Turb) 10 cm 2/3 sec-, E

w I tn 0

I T IJ I)

ll"'.\1_;

l,D V ~I 1,J ~14 (J

dlU

s C ,. ,.

<; • s t

~1 e ,, ~ D e

D~ CH

C l Cl C Z

C ;_ C i.

T T

T T T

(Oa)

(NO, N01)

(502)

O. 5 ppm

0. 2 ppm

O. l ppm

z N,X

s

"'

7>i0 J~n ir~o 69~

<; )

s s

f C8 t.;( ll

* ~ ,J P.

C C

r C

l l l

E l

T

T T

T

!b,... l

(Temp)

10 X 10-• m -i

O• - 100 ° C

B

T

"' 6~0 s fl ~ C f. l T (Dew Pt) 0 ° - 100° C D ~

l

t,' u ()0(,

'>70 ~) 4 U

5 5 s E S F

11 0 C 0

~ l

* e 13

l ~ I

C (

T

* .. .. (CN) 100 x 109 cm -a C

-; l tl ~t 140

s s

f f

D I)

ti 'l

C C

T l T L Figure 3.2.12 Aircraft Sounding - 16 July 1979

4<;0 s E D ~ .oz ~ • ., t) 5 E o e .. l'l(; ~ E D tt l*

1'>0 s D P. <>C

no 5 0 e l* ,100 s t 0 ~ lCT

.? 70 ~ r, ~ Zll

;?40 s r, ~ l CT

.no :, t Oh I * l ~ 11 5 ~ ;J l E T C

l 'iU s ,, 1: 1 .. T C

1/G q,)

<; <;

~ ,, IC ,, l

T T

t L

t)IJ - e I I C

1 •.; I I I I,, '-- 1 :1- - --- --- -t)- - -- -- - - l 1\--- - ---- l'>-- - - -~·- - ; ,1- -- ---- -,, :J- -- -- -- - 'JO---- - -- -(. ·J-- - -- - --10- --- --- - tjlJ- ---- -- -Q J- ___ ..,, __ 1l:O

µ-~c~~T G~ ~\Jll \(Alf

above this level. Figure 3.2.9 is a sounding made over Modesto Reservoir

about one-half hour later. The mixed layer extends to 840 m-msl. Above this level is a very dry layer from 1050 to 1320 m. Another ozone-rich

layer then extends from 1350 m to 1680 m.

Over the foothills to the east of Modesto Reservoir (Figure 3.2.10)

the mixed layer was considerably deeper (1260 m-msl). Above that level,

however, the ozone-rich layer was also found. The total ozone burden in the

mixed layer was slightly larger than observed at Modesto Reservoir. Figure 3.2.11 is a sounding made at Patterson on the far west side

of the valley. The mixing layer is considered to extend to 1020 m-msl with

high ozone levels (.18 ppm). Above the mixed layer was a deep and well­mixed layer characterized by ozone levels above .10 ppm. This layer extended

to 1980 m-msl. Winds within the upper zone layer were from the south to

southeast for all of the above soundings.

The aircraft completed its afternoon flight with another spiral

sounding at Modesto Airport. Low level stability had developed by this time (1958 PDT) and surface layer mixing was confined to the lowest 180 m (msl ).

Considerable ozone remained aloft, however, isolated from the surface sources

of NO. The total ozone burden above Modesto Airport was not substantially

different from that observed at 1658 PDT.

The aircraft took off the following morning to repeat the flight

pattern of the previous evening. Figure 3.2.13 was the first sounding made

(0541 PDT). Surface depletion of ozone is readily apparent to a level of

330 m (msl), corresponding to the top of the temperature inversion. At hiqher

levels substantial concentrations (.12 ppm) of ozone existed to 1320 m where

a dry layer commenced.

Figure 3.2.14 shows the sounding made over Modesto Reservoir at 0618

PDT. The mixing layer and ozone depletion extends to a somewhat higher level

but concentrations of .10 ppm exist aloft. Over the foothills at 0642 PDT

(Figuie 3.2.15) a similai pattei~ existed but with slightly lower ozone con-

centrations above the mixed layer.

At Patterson, on the west side of the valley (Figure 3.2.16) the sur­

face mixed layer (and ozone depletion) extends to 330 m-msl. Aloft ozone

concentrations of over .10 ppm exist but only to a level of 870 m-msl. Above

this level the dry layer appears as indicated in the Modesto Airport sounding.

3-51

(ti=Pl T vc..: Jl M,;P r,j 11-AP.<-n<J ?~:14:',? I-• Alit

Jt,1• 111//7'1 t<(uH: r:v~R P(INT LA~T~·(GCt/V,~~: blb/

ll""f": c:41:...:1 fLr '1:'it:3:ji 1-'I~. i;l-!(UI\L. £.Ltv.: 29 M(~'iLI

-1n---------o--------1O--------zo--------10--------41--------~n--------hC--------1O--------dU--------4O-------ICC l'"l\r.J I (; S *l 1 1-1n ~ S '>l T I 4 7L, (; s Hf l l ~,4U C s Pl T H•lll s l T') "C

I,, •o 0 5 •1l• T

I ·,~.J s 1.i. t l') T

I J lo -; ,, l T

l c' '-lO 'i J l T l li-JO s e TCl)

C1 i ~:) s U"I l T pn(; 'i 'Je l T I l 7 O s C·l l T l I 4 (J ; t ll e l T 11 Io s F l)t l ,,t ,J'J(i ; t l T• I •-J~ll 'i C e l T

• 1020 s t u e l T

L 9qc 'i E 1 ~\ l T T 41,0 s F C B I T I q30 'i t * L T

w T qoo ', t,; L T LEGEND I

(J'l u i;7U s l)d l T N •J 04U ~ DR l T FULL

~IQ s f C P. L PARAMETER SCALE llMBOL 7~P 'i Do l T 7~u s r-e T (1"urb) 10 cm 3/,- 1ec - E ,. s '-

1

1 ?O Ile T (Oa) 0. 5 ppm z

bQI) 'i Dill' l T M 0011 'i ~Dtl z 1 (NO, NOa) 0.2 ppm N,X 'i t.3U 'i E DU l T

t,QLl 'i l T (SOal 0.1 ppm sL 0" ', 7 ·J s E Dd l T 10 X 10-6 m -l B(b...,)•, 4 J s l T* ll ? 1 ') s 03 T T* (Temp) 0 ° - 100 ° C 'tl-10 'i IJ b lf T

4'Jo 'i 0 ftj ! T (Dew Pt) o•- 100°c D-T

·, lO 'i :Jr Fl T

1 ~o s * 1:l T Figure 3.2.13 Aircraft Sounding - 17 July 1979 j 1(J BU l T

't/L, s C ~ E l

301) ) l r"''' e ,! 1 ~; \ ~ i t,. ') ", I ti ,:: r ,10 ', t d·'.· T .. ,l~U '> T ,, T~l .-:; I) s I

l 1 ,, 'i t-:, 11 T

q,) I S ' <I, T ~

t,r, l ~ i \!1 I <; I l

-11)---------u--------L0--------21--------iJ--------4:)--------~f)--------h)--------10--------~~--------~11-------tcC t>f~(ll"iT ,:F Full ,C~Li,

F

l

. .__,_.,

r> t ;; t 72 I -A~ a - ,rn ~ 5: L4: 'l .'(i_rµLJ \t~ ul ~c~ nj

1,Y rl tl(ll'\( IK(l,llGAP: 111111-1 Ll\r'TKJl;Cl:/PA:.,S: f-;7t,/ Tl~f: ~:lo:£2 TL 6:l~:1~ ~,~. G~(L~i; LltW.: 7 "' P,' I") L ,

-11---------,1--------1a--------20--------10--------4~--------~c--------6C--------7n--------Bn--------QO-------ICC IC S df l T I

IC 'i bt: l T 1 JhO

I " ~ 1 1~, C,, I I) s ,. l 14-, -J JC S ~ 1-l T

l44U I QI Ml T I~ I 81 1 l F T

l :Hh.:i lF- ~ 'I [) T ,; L 1l ~ Sl 1J f l

l 3 2. 1) ~ ~) f l T l ,· -1,;i 51; d I: l T

l Lb li S,I le l T

UHi s u le b l T ) 7 Tinc "

!_) t TI 110 ll l .. ...l 1 .. u C l I I Lo ti l T- LEGEND IL PiJ' s l) l T"

A IO~CI s tLJ 8 l T FULL

L Io?:, f u b l T PARAMETER SCALET 'I'll! ' ~ u ri l T ~2h

I 'lotl s' E u e l T (Turb) 10 cm 2/1 sec-, E r 'IHI s f [, t l T

w I u 401'1 C L; ,i l T (Oa) 0. 5 ppm z

(J'I I) e 70 E D ~ l T w (NO, NOx) 0, 2 ppm N.Xb40 'i C D ii l T

ulu s E Ll l T" (SOa) 0. l ppm s 1PO ~ [) r l T

;~ 7 "lll ,; I., E l T (b,..,) 10 x 10-• m -, B 1?(1 s F u ti l T eQU s .',l, Ii l T (Temp) o·- 1oo•c T"

'., bO(J s blt l T (Dew Pt) o•- 1oo•c D

l h l(. E l T* b :),.1 f C::t> l T ... 1t, s C B F. l T S411 s D Ii 7t T Figure 3.2.14 Aircraft Sounding - 17 July 1979r., 1(1 ., t' Tu ti l ~~d s I) T 4';(1 5 (, " b l f T 4/;) 0 t l c T ,HU s 0 e el l~O , 1; t l T ~

·, L; t I I. T j i '·' .3) (1 0 H l t T 2 71) C e l C 1 l~G C ~ I I I' tlll ·) IJb T l H;; \ LJ~ I I l "i ,i 'i " 1; ,:, T I 1 )I) , r ~ [ I I"

Q, I qf !J I bu I I

-1r1--------- >--------1n--------2~--------11>--------40--------•,11--------~1--------/1J--------dr,-------- 0-------1on P"M(L~I nF fLLL SCALI

COFPLT v~~ \l ~0n 03 /1-APR-dO ~~:to:~L PAf.t 'l

CA Tc: 7/17/7<1 ~CUT I ·,1 a PCl'-cT I

LAPTRIUCt/PAS~: ~/6/ 4 11Mt: b:4L: 'I TL t:~q:44 ~IN, r.~CU~C 1:lrv.: Z74 ~l~Sll

-1n---------o--------tn--------,o--------J0--------41--------5o--------bO--------71--------ao--------9o-------100

o•-1oo•c T

171'11 I C C SFS l T I 17,,ul u CfSJ l T 1710 I '.J *5 ~ l T lo'IDI tJ L~EB l T l t-;i;d [) c.s * l T l 6 ;•q 11 s~ ~ l. T I 5 ,10 ,) *C p l T l'ih0 n SfC 'l l T l i)-;10 I) 5 b* l T l "l Gu I) SfL 4 l T , .. JI) I) ,. d l T 14ll\)

[', 'LJ O*~

:-;:::: ti

rt l

L T

T LEGEND

11,l 0 F* B z T 1 J'lO S*D •\ l T FULL I J.'U *CD H l T PARAMETER SCALE .[:!.M!!.QJ.,

A

1zqo 1 /. 1'>0

¢((;

*C.G h

,l l l

T T

(Turb) 10 cm 2/3 sec-, E

l lllO S* C B l T (Oa) 0. 5 ppm z

w I ...(J1

T I T

u ,J

llOO 11"70 1 t•• u 11 l 0 l O 1~0

S* C H

*S C d C B*s

us ~* ,. tC ~

l l l I l

T T

T T T

(NO, NOx)

cso.1 (b,.., I

O.Z ppm

0. 1 ppm

10 X 10-6 m "l

N,X

s B

~ I O'>tJ * tC ti l T (Temp)lldO IJ S* ~ l T

'I >u I) SCt ll l T (Dew Pt) 0°- 1oo•c D ~ 91t,•., ~ 5Ct B l T

<; 3J *( I. d l T 100 x 10• cm·• C

, (CN)

1-1 q~o SOL I: tl l T ~7J , * l T I*

l eoo :, eC 11 ~ [. T I

C !J B l T Figure 3.2.15 Aircraft Sounding - 17 July 1979 I81U * I7PJ * (, lJ B l T I ., 'lU s t C I) 8 l T I72U s C CE l T I

bqC s * d It T I

t,t,U >* B f..i T IH , l To~O ' (, u I

<JU:J s ( o, e l T I ~7v '.il:.C ~ fl T I .,'l1'tt) 'iltJ l T I ", 1 0 '> L n ~ f L T I

.., ~i IJ ,c I T I I ..,,o :, L d t., l C T I

.t., l l, , l d GI f r I

l'-Jd ·, L - I T

)hll ,c l T c I

"·' L r" l"" -; T T:,,r)·) L I!'

>-••••• .. -f,)••••••••••·•••'"•••••""••••••• llf <' 1 <, I-1 ·)----- --- - ' -- -- -- --1••--- - -- - - t'.0-- -- --- - \1)------- -4,1---- --- -~(J - .. - - ...........

t'ttt(f 1111 ..,,- ,t..ll •'-•l•

PAlJt I JU-APk-tlil ~5: l't:02CtH:i:,l T v f:N tJ l t-'t.hl OJ

1-· CL, T t- Cvt~ PCll-,l !>C~T· 1t11l1~ L~kr~ll1CE/~•A~S: ~,o, 6 TIM : 7;,2:~7 TJ 7:4d: ~ ~IN. GR(U~C flcv.: lU t'C~SLI

-10---------0--------10--------2u--------su--------4,>--------~o--------6C--------1c--------80--------9o-------lOC Is 1t1 IO S H t l T I I, Od

(41.> IO

IC S

S l>t *

l

l

I

r I

14 4-., I~ I 0

IC I u

·, S

-> *

l l

T T

I I ~O I D :, "- l T I J 'io I u :; :.,; l T LEGEND 132u IJ S H l T

l /4l: s cl * l FULL l lbG UH, lLOU

n [)

r,

S e tl S ,, El

c; K ,: Z

T T T

PARAMETER

(Turb)

~ 10 cm •1., sec-,

SYMBf&

E

I J 7L, 1140

D fl

'> c;

u:' M

l l

l T (Oa) o. 5 ppm z

11 I Cl l OfiO

lO"'u

11 J C

:)

s

~

tl

"

l l l

T T

T

(NO, NOx)

(SOa)

0.2 ppm

O. I ppm

N,X

s A L

11,n, -,i(t,

ll 0

s s * l

l T T (b"""')

10xl0-4 m- 1 B

w I Ul Ul

T l T

Ll

960 411] ,rnn tt/0

D I)

r, ,)

:,

,,

* * * l

r T T l

(Temp)

(Dew Pt)

o·-1oo·c

0 • - 100 • C

T

D

I) ,140 \, .;: h l T ,, hill /Ru

s s

(: llH

f ~

l

l T T

Figure 3.2.16 Aircraft Sounding - 17 July 1979 7"lfJ s t c~ l T

"' 72J s ,. 8 l T t,40 ' i:u ~ l T ,. bf>(J 5 c lJl1 l T

~ tdU :, f f) e l T L t011 s E ll 8 L r

..,_ 7LJ s t- ,u B l r ~4U s 0 B E l r ~10 s u 8 * T 4HU ) ,; H t l T 4S1 s CH .. l T 4li, 5 D l r l l j~J ', .. l T >bl) s t* l T ~1 3 tl I s l T :,ou s n E ~ l T nc s ll H l l T ~ 4 0 s 1 H T LI I) s (; ~ l ., I et. ~ l ttl; l '1 lJ

1 l1J

l l , t.•)n

u b :.;, 40 l s :1,

t,I,) l 5 .~ I l

1U l :, 11;

- 11--- -- -- --•)- - -- - --- 10- -- - - - - - c. C- -- - - -- - ·I :1- --- --- -,, ·J- --- -- - - - 'lll- - - - - - - -~ ·)-- -- - --- f •; - -- --- -- df)-- - -·----91)- ------ .l 00

P<k(l·Nl Jf H_;Ll 'i(Mr

Winds in the ozone iayers aioft were from the south for a11 soundings made during the morning. Transport of ozone aloft from the southern part of the valley to the north is indicated in this series of soundings.

3-56

3.2.3 Tracer Test 2

Release Location: Manteca, San Joaquin County

Time and Date: 1300-1900 PDT, 7/16/79

Amount: 104 pounds of SF6 per hour

Release conducted during northwesterly winds of between 2 and 3 mps. A

southerly flow on the eastern side of the valley (the Fresno Eddy) was replaced

during the course of the release by northwesterly winds.

Initial transport southward

During Automobile Traverse 1-1, beginning about 1500 PDT, a peak SF6

concentration of about 630 PPT (880 PPT/lb-mole of SF6 released/hr) was

detected near Modesto along Hwy 132. The peak concentration was detected

slightly to the west of Modesto. 94 PPT of SF6 (132 PPT/lb-mole SF6

released/hr) was detected during the 1500-1600 PDT automatic hourly-averaged

sample at Modesto (see Figure 3.2.17). At the Modesto hourly-averaged sampler,

70 +/- 15 PPT ( about 100 PPT/lb-mole SF6 released/hr) was detected between

1500 and 1900 PDT. The timing between the start of the release and the

detection of SF6 at Modesto was the same as during the first Manteca release.

The concentration profile was centered farther to the west than during the

first test and center! ine concentrations detected along Hwy 132 during this

experiment were about double the corresponding center I ine concentrations

detected during the previous test. The detection of higher concentrations

during this experiment is surprising in that the release began during the early

afternoon rather than during the typically more stable conditions persisting

during early morning. The unusual meteorological conditions alluded to in the

previous test were evidently the source of the enhanced instability detected

during the first test. SF6 concentration profiles detected during Automobile

Traverses 1-2, 1-4, 1-6 and 1-7 showed an SF6 peak near the same location as

found during Traverse 1-1. The maximum concentration detected during the

traverses, however, tended to increase throughout the afternoon. Maximum SF6

concentrations of 632 PPT, 643 PPT, 860 PPT and 1248 PPT (1753 PPT/lb-mole SF6

re! eased/hr),

3-57

SJV-2 7/16/79 - 7.'18/79 150 ,- n-rn MODESiD

0 I f" ' LH I / I I hi I / / 6 , I ,:111:!l:111:111:!!l:1tt:11t..Ji1:1:111..J4,, / I I I I I I I , I I 150 -

PATTERSON 0 I + , I , • I , , I • L L I I O I , , L • t l l:lf:tl:tff:tH..J:tH:11:til:tH:tH.,J' , l , , I , 1 I , , I

150 .= GUSTINE

0 I , , I , +L-1 , LIJ]-1 , Lj / I / L I / I I / ,.,J.,,., I / / I / / I / / I I I I / I I / / I 100 .-

DOS PALOS 0 L, , I , , I + : I t:::d-t--t l I L ) , , I 1 1 L , '4t4 ,.,.l*/:!11..l:!'1*'..j:!1:!!1:iil:!1:1!t:ttl:!t\ , I , , I

100 r TRANQUIL lT¥

0 L / ) / I I I / I I t1=il=6 Ll4U I 1:11;1.,J:!l:::I I / / I / LJ / / kt / I L / I / / I / I I 100 -

OAKDALE 0 I ,,+1 , , I , • 1H I , , I I k-4 1 J INI , I /:IH..,J:!H:IH..,J:!H:IH.,J:!H:IH.J:Jll1' , I • , I 1 1 I , 1 I

100 ,- · MODESTO RES

l­ 0 I + , I 1 1 b,,,J..,...,*L , I ' 1 I , 1 l .1 t I : , I , /1M:!1:1H:td:11;1:111:tl-w,. 1 I • , I 1 , I , , J a.. a.. 100 - LIVINGSTON r,

CD 0 I , , I • , l 1 , I , J , 1 L 1 6 ..1 l • l!,JH*i...J:1114 1..j*i:ll1:IH*i*1.li11:111'4 1 1 I 1 1 I 1 1 I LI. U) 100 -L...J MERCED

0 I • , I , ,rL--ttJ , U::t , 6 cJ u I H I H I , • I µ I , d , , lJ +I , , I , , l 100 ,-

CHOWCHILLA DI LI I I I I I ,L. I I bl L I I I I I I I I / / I I I I t:'H:lfl:JII

f I I I I I I / I I I I I I I I I I

- I

10i -MADERA

0 l,1, I, 1 I , 1 I 1 ,-Ill , 1 I 1 1 I u I H b--, I 1 • I , kb • I , , I , , I , , +, , I 100 -

FRESNO 0 L., • ) , , I , , I , +l+ , I w I t d , , I : , 6 1 I , , '*' I 1 1 I , , I 1 1 I • • I

100 ,-O'NEALS

0 L, 1 I , 1 I 1 1 +1 1 I 1 , l,, 1 I 1 1 L, : I • 1 L, 1 l H Li:!1*l*1:111..J:111:111:4tt:tH:it\ 1 1 I 100 - n MARlPOSf.

0 I j : I ! .,..J I I ...... L u ~ : I LL~ L I- L1 L1 1 lNL-lli~*I..J'!t1:111iJ'!tl" I I I I I I II

12 15 18 21 24 3 6 9 12 15 18 21 24 3 6 9 12

PACIFIC DAYLIGHT TIME

RELEASE LOCATION: 621 LBS SF6 AT MANTECA RELEASE TIME: 1300 PDT, 7/16/79

Figure 3.2.17 • INDICATES MISSING DATA

ARROWS INDICATE <:Ut,DS OF SAMPLING PERIOD

3-58

SJV

2

I 1

.... , l

~,rt,na ·

~Qr ~Cl~w:~7-~fcfi r,dro -...-fywar

ij4 .,

~uno~F"·!.

.-

_,

--~-- ~

t;\,. I. -'lfArl,,t..

:.TA,·.,.13- \ I

f,ittn,"• rAr!~

',

,... I 1,,o•fA...,._ • ~ k..JlllfT.' ..,_ '·

' .- A ......_ J'G ' f ~

l. Vall

. A

t::_~ .,

Figure 3.2.18

* INDICATES SAMPLER LOCATIONS ((~·: IS THE RELEASE SI TE 3-59 ~

respectively. As mentioned previously, Traverse 1-1 began about 1500 PDT,

while Traverse 1-6 began at the end of the release (1900 PDT). The increase in

concentration detected during these traverses was probably due to a

increasingly stable atmosphere as evening approached.

Continued southward transport during evening

As in the previous test, the tracer was detected west of Hwy 99 during

traverses along Rd J17 (west of Turlock), Hwy 140 (west of Merced), Hwy 152

(west of Chowchila), Ave 7 and Hwy 180 (north and west of Fresno). Typical

concentration profiles along these traverse routes are shown in Figure 3.2.19.

The maximum concentrations detected along these traverse routes were 424 PPT

(about 600 PPT/lb-mole of SF6 released/hr) along J17, 347 PPT (490 PPT/lb-mole

SF6 released/hr) along Hwy 140, 112 PPT (158 PPT/lb-mole SF6 released/hr) along

Hwy 152, 55 PPT (78 PPT/lb-mole SF6 released/hr) along Ave 7, and 56 PPT (79

PPT/lb-mole SF6 released/hr) along Hwy 180.

The hourly-averaged samplers also showed behavior similar to that of the

first test. During this test, however, Gustine received high concentrations of

SF6 (maximum of 116 PPT, 164 PPT/lb-mole SF6 released/hr) while Livingston did

not. The tracer plume was thus detected farther west during this test than

during the previous release. Dos Palos and Tranqui I lity were also impacted by

the tracer plume. The arrival of SF6 at Dos Palos (2200 PDT) corresponded to a

mean transport speed of just over 3 mps. Tranqui I lity was close to the

centerline of the plume in that a maximum concentration of 41 PPT (58

PPT/lb-mole SF6 released/hr) was detected between 0200 and 0300 PDT, 7/17/79.

The arrival of SF6 at Tranquility (0000 PDT, 7/17/79) corresponded to a mean

transport speed of about 4 mps.

Gaussian plume model comparison

As in the previous test, the traverse data can be used to evaluate the

dispersion parameters for the Gaussian plume model. As shown In Figure 3.2.19,

the concentration profiles along the traverse routes were essentially Gaussian

in shape. Figure 3.2.20 contains a summary of the horizontal and vertical

dispersion parameters estimated from each of the traverses. The solid lines in

3-60

TRAVERSES SJV-2

TRAVERSE 1-2 1600-1639 PDTHWY 132

TRAV 1-5 1858-211144 PDT

J17

HWY 14111

HWY 152

'-,,

____,\._\..t.tADERA

AVE 7

HWY 18111

FRESNO

3'!1111 PPT I Figure 3.2.19

3-61 NORTHERN SJV SCALE - 1r 208000

SJV-2 100-

2:: X

LL

••

LL w 0 u z 0.... (/) 10 D:: I.LI Q. en .... C

•N.... D:: C::c

• ~ LL I.LIB 1000 z 0

(/) -D:: UJ Q. en

100 -C

...= D:: I.LI >

GAUSSIAN COMPARISON

,.A a C

0

() ----------~D

I I10~·--------.-.__.,......,_._,.,~•~•....________________.......,,~,-1• 10

0 DATA

100 1000

DOWNWIND DISTANCE. KM Fi gu re 3. 2. 20

TAKEN AFTER END OF RELEASE 3-62

the figure correspond to the predicted coefficients for each Pasqui I I-Gifford

Stability Class based on extrapolations of the curves presented by Turner

(1970). The vertical dispersion parameter was again back-calculated from the

horizontal dispersion coefficient by mass balance considerations. As noted in

the figure, the horizontal dispersion coefficients slowly increased with

distance downwind but were generally consistent with Pasqui I I-Gifford Stab ii ity

Class C or D. The apparently decreasing stab ii ity with increasing distance

downwind is surprising in that the shorter distances correspond to

mid-afternoon while the larger distances correspond to the presumably more

stable evening conditions. The calculated vertical dispersion coefficients for

each traverse corresponded to Pasqui I I-Gifford Stab ii ity Class D. The

calculated vertical dispersion coefficients are also consistent with a more

unstable atmosphere (than stab ii ity class Dl with a constant or slowly varying

mixing height. An average transport speed of 3 mps was assumed in the

calculation of the vertical dispersion coefficient. Due to the uncertainties

associated with the vertical dispersion coefficient calculation it is not

possible to determine whether the tracer slowly mixed upward continuously or

quickly mixed within a wel I-defined mixing layer. The estimated mixing height

in the valley, based on pibal data, was 2-3000 ft. If the tracer was

wel I-mixed vertically, the vertical dispersion coefficient calculation suggests

a mixing height of about 400 m or about 1300 ft.

Carryover of tracer

As in the previous test, low concentrations of the tracer (5-10 PPTl were

detected over a wide area north and west of Fresno on the day after the

release. Again, the night and early morning winds apparently redistributed the

tracer throughout the northern valley any tracer not transported out of the

valley.

3-63

Summary

Many characteristics of the first release from Manteca were repeated

during this experiment. An overview of the transport path of the tracer Is

shown in Figure 3.2.21. The tracer was again preferentially transported down

the central and western sides of the valley.

concentrations were detected on the east side of the valley, San Francisco Bay

Area or California Delta pollutants transported into the valley apparently had

little effect on valley air qua I ity.

It was possible to interpret the dispersion of the tracer in terms of the

Gaussian plume model. The horizontal dispersion corresponded to that expected

under mildly unstable atmospheric conditions, Pasqui I I-Gifford Stab ii lty Class

C or D. The vertical dispersion corresponded to that expected in neutral

stab ii ity, Pasqui I I-Gifford Stab ii ity Class D. The vertical dispersion was

also consistent with a wel I-mixed layer with a height of 1300 ft.

As in the previous experiment, low but non-zero concentrations of the

tracer, were detected on the day after the release. It was not possible to

quantify the amount of carryover from the release day.

3-64

lb. e.-ci

<,.I I

O'I u,

'o.......__, 1.,,..._ ..._,......... -\

'\ Cv

~ ~,. ~~

~

! IEl.00: S11£ - fVMEr.A I

11CAU IO 0 IO 10

HllU

0~

~~ _j

100o

ARROW POINT INDICATES OBSERVED TRACER LOCATIONS NUMBERS REFER TO HOURS AFTER RELEASE START (1300 PDT., 7/16/79)

Figure 3.2.21

3.3 Test 3 18-19 July 1979, Livermore Release (1510-2030 PDT)

3.3.1 Meteorology

Genera1

The synoptic meteorology of 18 July, depicted in Figure 3.3.1 was characterized by intense ridging aloft on the west coast, extending well up into northern Canada. Warming of the temperatures aloft due to subsidence is reflected in the plots of 850 mb temperatures at Oakland and Vandenberg in Figure 2.2.1. At the surface, thermal troughing due to heating of the interior resulted in onshore pressure gradients. A high pressure area lo­cated near Four Corners reinforced the surrvner monsoon flow over the southwest desert, allowing moisture to penetrate into central California at middle levels and causing widespread shower activity in the central and southern Sierras. Skies in the valley remained clear and visibilities were generally good except in the northern portion. Stockton reported visibility restricted

to 4 miles by smoke. Temperatures were several degrees above normal with Fresno reporting a high of 108°F.

Transport Winds

As shown in Table 3.3.1, the surface flow at the release site was directed towards Altamont Pass during the afternoon of the 18th and until

......... , I.I,...,_..., .,..,..,..,..,4,. .,.,, ... _.._,..,..,.t -.h..-.,,+ t:.. m/~ ; n~arl_y 111ur11;,1~ on the following UOJ • n111u :::,t,Jct:u:::, OVCIO~'CU OUVUL. V Ill/~ Ill

the afternoon and increased to a maximum of over 8 m/s in the late evening. By 0300 PDT on the 19th, the winds were no longer directed through the pass and speeds decreased. From the pibal data taken at a location 4 miles east of Altamont Pass sulTITlit, a time-height cross section of the wind component representing flow into the San Joaquin Valley axis was developed and is shown on Figure 3.3.2. A main point to be noted from the cross section is the persistence of a significant component of the wind directed ino the valley at low levels (18 hours duration or more). The flow maxima occurred between 2100 and 2300 PDT on the evening of the 18th. Depth of the flow was about 500 m.

3-66

f­C) 0..

U"l 0

,._ °' °'..... >, ~

::, ""'.:)

CX) .....

V, ...., '-­ttl'

.c:: u '-­a.,

.c::...., ttl a.,

3 a., u ttl

'+-5

Vl

..... M. M

a., '-­::, O>·-LJ..

3-67

Table 3,3.1

SURFACE WINDS AT LIVERMORE 18-19 JULY 1979

Time Wind PDT) (m/s)

July 18

1600 255/5.4

1700 245/6.0

1800 250/6.6

1900 250/6.8

2000 250/6. 0 2100 245/6. 5

2200 245/7.9

2300 240/8. 4

July 19

0000 240/7.4

0100 240/6.3

0200 250/4.7

0300 190/1. 3

0400 120/1. 2 l'\L n. IL A0500 C.-:JU/-:J,'t

0600 095/2. 7

0700 150/1.6

0800 155/1. 7

3-68

2 2790

2520 ~ 2250

E ~

Cl 1980z ::, 0 0: (.!' 1710 LU > 0 co 1440 ~

I-:c t!l 1170..... LU :c

:)'896

612

313

C'\ '-'

0 m/s

0

2 2

;---0 0

13 15

Figure 3.3.2

17 19 21 23 l 3 5 7 9 11 13

TIME (PDT) 81 /030

Time-Height Cross Section Component Winds (m/s) From Altamont Pass 18-19 July 1979 (Positive Component Represents Flow Into Valley)

3-69

Flows within the valley during the test can be described by the streamlines constructed from the 1000 foot measured winds from the pibal

network. The 1500 PDT flow is shown in Figure 3.3.3. From the stream-

lines it can be seen that northwest winds were predominant in the northern and central portions of the valley. By 1900 PDT (Figure 3.3.4) the north-west flow extended throughout the valley and persisted until the following morning. Maximum speeds ranging from 8-9 m/s were observed between 2100 PDT on the evening of the 18th and 0100 PDT the following morning. By 0500 PDT the Fresno eddy was established (Figure 3.3.5) in the central and southern

portions of the valley. Subsequently, winds dominated the flow in the southern half of the valley through 1100 PDT.

Mixing Heights

Mixing heights were measured by the aircraft during the afternoon flight on July 16. Heights were determined primarily from the characteristics of the

observed ozone and bscat vertical profiles. Measured mixing layer heights are given in Table 3.3.2. In two of the soundings, there were two principal layers. Heights of both layer tops are given in the table.

Table 3.3.2

AIRCRAFT MIXING HEIGHT JULY i8, i979

Time Location* Mixing Height (PDT) (m [above ground level])

July 18 1645 Modesto Airport 210 (690) 1747 Brentwood 620 (1250)

1830 Livermore 560 (* Distances in miles)

3-70

.... .,, <", ..,..

,:_, ••c.11:!!lf'•

. . . - . - --.._ .-,·- '

L, • ~ •.•

Figure 3.3.3 1000 Ft-agl Streamlines - 18 July 1979 (15 PDT)

3-71

-C'

N I

9tM.I ...

-~ C "! ! tf' r l•

. . . - - - --Figure 3.3.4 1000 Ft-agl Streamlines - 18 July 1979 (19 PDT)

3-72

------

- --

/~ ~ ~---------- . \

l - r 1· - ~ --~~~---------' \\ :\~-l-- . / L

ll '"'°""•,;\\ '--~w ~~ j'> '\.- ,. ('._ ()

~~ ~ _ii t1p '1;-t,( kt-;~~--: ~ "\/..... . i \ -\... ...._ \\.j :•~~ ..'T0 . - .. w-...I?_

c; "-' / . .,,... • '·"-..-,, v-... - - - ·,1r0·~ ~. . --:', C''\<·1"' 4,-,

\.:~ b_ , . -~ _,.;;, >~-,-~?~\:: ,- - -,.....-.--%-~ . -. -~~fo~·-?-:2~_

5u11 ·~~-> "\.. ~--" - .:-,~.. '-

"'"'~"of~t~~\~~ > . ~ ~ -~;-:t.:sl~ '\\ ·-,..,. lt;:.-,·".C:?::..~ < t~ C\.._ ~ <-'~ I \1.~'-7'"',: ,<; . . - ~ "\,.),. ~" ~~- \I '•l <,.) .. - C. ~ _, ~ - •.- ~ ---~,, I \ ~ ~ ~ - .....,. ~'-~~-::) (

~~\:~~ . . ____........_ ' ~~~~~\ \

(· ~~ ~-- ~,:\·. ... y -~-- :s.:_ ·-<';-..... ~

-4.~, , ..... - . "'_: , al "'· ' . ~ .... -.. ~

~

-" ..

\

; ' ..;;, ~. .,,, ....~

f

N I

. ,.. .... ~- ... ·- ;,·

. . . - . .,

.:!-,.

..... .--·

-~ --;·

Figure 3.3.5 1000 Ft-agl Streamlines - 19 July 1979 (05 PDT)

3-73

3. 3. 2 Air Quality

Regional Pollutant Levels

Maximum hourly average ozone concentrations throughout the valley on July 18 are shown in Figure 3.3.6. Exceedances of the .10 ppm standard

were frequent within the valley. Highest observed hourly concentration was .17 ppm at Fresno. Locations within the Sierra National Forest recorded values of .11 ppm.

Maximum hourly concentrations of S02, CO and NOx throughout the

valley on July 25 are given in Table 3.3.3 together with the maximum values recorded at the Rockwell International vans on the same day.

Table 3.3.3

MAXIMUM HOURLY CONCENTRATIONS JULY 18, 1979

Parameter Location Maximum Value fnnm\..,..,,.,

S02 Bakersfield .02 co Bakersfield 2. co Fresno-Olive 2.

co Stockton 2. co Modesto 2.

NOx Bakersfield .19

NOx Modesto (RI) .01

NOx Merced (RI) .05

NOx Madera (RI) < .01

S02 Modesto (RI) < • 01

S02 Merced (RI ) < • 01

3-74

V

~-- c; ~ ',. -A."'1.7-z~

~~

...... .....l. ~~~-- •' ..

C' <"

-~ .. ,.,1•, ~

·. '

"--' . ~ ~- -..

:x::::::::::=, - --••etolO-OICI•

' ---

t. I --- -~ ---~~-::.-- · 2-- -- - - -- - - --- -l. L_:.~~s ~~-e-~~ \_ ,/1_\, ~ ~---::

'.\:w r,.,f: ~ ~- . J~ ',, .f'~~ '- r

Ve~~ ~y "l"'?JZ /,. :.~~~~ ~-,_ t \ I( ~ • iJ -\S<:,_,~,,TO ft y~-:_~~ •,,~ '5\ ~- ~t4 =-: ~~"'~~~~~::_

L t_f, ~- / I ""-~ ~ J'§> ,_\~~ts__~~~ 11 l\ _ / , ; _-~ ~~)-,__ r "'~ ~~\\.-- . - ~) ~- 0?19 ---------~-I ,,_'.',".,cof.:-':,,....,:., ~ ;;:,~~~~~- \~ \ --, __

L --~--;,-...:.-,:;;,_"" 1-N ~ ~ -- --~~ ] '1\ " , '·-" ..s ) -;,,;= "i""'..,,, -.:k: -- , . ~ Lb \ ·.~I t~<-.. \ ?\~ c.-"$_ 12 ~;:, . ~----~ _?~>----·-;: ~ "·C. I \.-. '----2,. t ~ '? ts · ~ ..... C\... ','\ l ! \ ")_~~---:- ~ - . iS--S' : 12 10 \f(_- ·- ~ "'·\ -~ ~ ~ '

(~"~ ~~~~ \,t ~~ -~~~• i·•••m li-. c--._ - ~ . 10 / ( . -- '"' ~ 'JC ~14_/') ·-1-..S,--\ /_-, _ , ~ \ t'·-:s~ _ 1 .;;__~ ~ -~ ,

-~/q

11 ') ' r - ~\ ,( -"-\, I •--:- 1 . - " ~\ ~ 5 -;,--...-_ -\: \.

- ~ \:~ ~ '\ I --.._ • 0~.~y ':~~- ~ ~•~--;;-, ', - ;

'\ 7-,_ , ••, - - --. vi,, . \, --1-'"' 8 ' :

•• ~'< ~' ~~'-.,, 12 '---'u - •,, "- • ', _ \ C' :-...\s. ', \.f, ' ~ - '-' . \

~

0

N I

,:.u.1 •-•-_!=_':'! X == ~

(- Figure 3.3.6 Maximum Hourly Ozone Concentrations (p-phm) - 18 July 1979

3-75

1

Aircraft Sampling

In conjunction with the tracer release from Altamont Pass, the air­plane sampled in the late afternoon (1645-2000 PDT); concentrating on a

triangular route between Tracy, Brentwood, and Livermore. Two altitudes were traversed between Brentwood and Tracy, east of Altamont Pass, and at an altitude within the surface mixing layer on the other two legs. Sampling was also conducted within the mixing layer in the valley to and from Modesto. Spirals were flown at Livermore, Brentwood, Tracy and Modesto.

Figure 3.3.7 shows the flight pattern followed on July 18. Table 3.3.4 gives the overall air quality characteristics observed during the flight.

Sounding profiles for Modesto, Brentwood and Livermore appear in Figures 3.3.8 to 3.3.10.

The sounding at Modesto (Figure 3.3.8) shows several layers of pollu­tants. A lower layer (to 240 m-msl) was capped by a high bscat layer between 270 and 510 m-msl. A very dry layer is indicated between 750 and 1080 m-msl

containing relatively high bscat values. The wind flow in the upper layer was from the northwest.

At Brentwood (Figure 3.3.9) there were two main layers, both charac­terized by high ozone values (maximum .22 ppm). Above 1260 ma very dry and

clear layer is shown. The sounding at Livermore (Figure 3.3.10) shows a well-mixed layer to

750 m-msl with values of ozone to .10 ppm. Above this layer the dry, clear air was again found but a second ozone layer was centered at 1050 m. The wind direction at the height of the second layer was from the west.

3-76

w I -., -.,

\ it.,d ~.\:.,, l~' 0 ~ • '-.._ I)22 1RM

11 / /ON!'1"~_ 6 \s•:(~l'cf'••· i' '1(', k,\~~:C, •, · -_\.'>_ •_I 1-f'\\\ / -i-'<-i~•~2~-

J-,, o:',-,f'!r-C__ - )~,I•. , 6lL'-< \ , \ :\:,J ,- ,-.,~ "'"'"""': .. --~ , \\\, o II ~ 1

.:_:,,, "')-' " /, ~ -\~.~ :,..· )1'~-'-"'-!-:..::rf~ ,;1~.J "'"'···· Lii-'.1/v ·-~~os~- _,~er..,.'½\ OJ \, _ . / \ ..[,~ '\ ~~-.. ;,: '. ,\) °\:~·~0

• i \At ;, c-:;:; ;,.._ \/7 ,. <;;:; ;~!~ ~~~ - - ~ A,~ ..:,uh1not ·•./.:.._~ ./ • ,· • ...._.µ.i..;..'--'-.,.+.,,._~~..,__._~......I.) . \ . ~- .. '"'-I·:\'-./ ~ < '

!lo., -...,, '

~~"?7"~v:r-,......~,

\ L.L

:,.;:

,/1~.f

.,... j

~

8

:13 "

~ANf◊•A~I~.\--~::::--.. .. ---:---'"/1 --:,-· '~.._:_·:,x:,:G,',;b ·.;J.,c-"k;:::: 'I ""'I''~ J .,..[ ••••• ....:.t·~-.:..-.....->::-,~~~-::y/,-;:';.,, :M• ~,~·-~4~0,·~: ,,.•/ ?25s·~::1r-(>,. ';K~~l "•'·::..• ·t;!\_-----,,1)~, '-;;;;-;-;;-' ,, :=_ i', ... ,? ~< (-.i.j·'. \~·/LI_':::·"··-·_'."·~\~,·-r,,:,..,·7 . _.'.r:,~ -.-, .'.:. .. ;----::.... v~. · .. ~.:::,·"1'1v'--,,0.:J•l4_/'\..:..11\'1< '',--+,.Ii.,-·.1 ,, V 11... •

,., ) "7"0 6. 1 ,, ",.;> '< I 1 .. 1 1_'\. .. - _....__.-. -,,, -1· /.,, .,,-, ·~ v.-, ,,,,- 1/ (i'• 1 1 ,•,~~1\'f , ,,, I f, 1:•11 !l.l' , '

<J"\ • •~- _ - - '.;-, •,,,. -:i, _.. ,':' '" / ...... , ',,. ,',,"\ .:., , ·•.:: I\ ' J \ I• J.-. •ce:.·..: I ,'+I<)];~~·,,,>, \ ,. 0 -------, , . [ ,~--·-- r . ; ·· ......~"' ~ :_.___..,, tA-1 fAPf", ."' _, - ....... I~\p--r l~ 41~:1:.'l(~ /I\, ~ ,,. ,..... •,r • 1 1 ..~ r-~ ?, _ ~~·-----,·) /', , 1:.;,n • f'i'j ,, • 1 - ._ -~ .,.,._ .,,,_,.__~ 7 /1 .

-:''Y/.•t \ 1 • < '"' "·'' ::)(:_. ·t•µ~:~.:• ,\J_1 •• \'/ ., '""-. .._,(J ;,~•~";;,,,.•~; .,N"'t:<"• .._~ ~~ ~...._ •~'1\~'~ L'~,', ~i~i ~--: ',, ',Scale /'.' . \ /' l \·i.,,"r•:•·;,// " ·~ 1· I' ,'\ ,;;,••. , ,,.\,.lc'~·~I,_ - i I,

0 ' ' I (.\•IJ.47 / . :-. 't ,\v·, ,t..l ".., I ~'l nr1~ I' --------• ,I ( •'.J~j I ~• I j _J._ j I I I lr.1 .. t (',I;,_~ r-•l -::,<"J ,::-,\.:' \ I l\' 'f ..,,.::-:-.::~ ::1..: • •• ~- c__j

10 nm -I .. .

JH 4 I I ' I ···,: \,:I .... ) ( \··',! .J.,·,-~. 1-- ,, , :fJ'(l 1I ~:.~)•~ (.'r ,.,1

~aMl"'l\ i:iH,-.,, ~11-,. ,.c. ,\, __',_./':' - 4089_••• -~--...¥,...,..,_ __ _.._' _ _; ,_!:,PATTJR',t,. •Jt,~(1, ,~°7',';\,._,• I •_I 1./\ ~--~~ ,,r,, ... ,

<;:AMPLING ROUTES 18Julyl979

Figure 3.3.7

Table 3.3.4

AIR QUALITY MEASUREMENTS CARB SAN JOAQUIN JULY 18, 1979 SAMPLING

VALLEY PROJECT

Start Time (PDT)

Location (Point)

03 Mean Max (ppb) (ppb)

bscat Mean Max (xlo-fim-1)

S02 Mean Max (ppb) (ppb)

NLix Mean Max (ppb) (ppb)

NiJ Mean (ppb)

Max (ppb)

0646 1 37 152 145 ll08 0 33 6 44 4 34

1719 1-2 147 241 163 ll96 1 4 14 32 4 13

17•H 2 132 223 82 196 0 21 17 36 6 18

1812 3-4 117 179 86 144 0 0 20 36 5 13

1830 4 71 145 51 130 0 0 17 44 7 15 w I 1844 4-5 94 165 82 200 -1 0 23 41 10 28

-..J co 1855 5 66 76 37 68 0 0 8 15 8 15

1916 5-3 71 82 35 70 0 0 19 27 12 20

1929 3-5 161 176 109 156 0 0 24 36 7 15

1943 fi-1 158 192 131 266 1 4 23 40 7 15

Pb.Cr lf IJFPLT VfR Ill MtJ'l J.l 00--00 1J:1~,1~

4..Cl.l• ,.,-'It-~ f-'(l~l~.llt·: 7/lt/74 L4RTe I LCI /P4a'i: b1 I'/

~I~. !-rl[L~C ~L•:~.: ,. I 1" :) l)llMi: lo:4',:e, Tu 1,,"i:1~ 4

-10---------o--------1~--------2c--------jn--------40--------'>D--------bC--------10--------oo--------~o-------1co h 3U IC S ~ * 1 l T l',OU IC $ 1\0 f l T l470IC S/1,~*l T 1,4v IC ~ *o"< T l'tlO,llJ S*Otl T Jj~O • _ 'i t\·99fL l 13~0 l 0 s lI\,. T

l 320 II Ll s I<.• L T _; <; ,. ,";,:_, TI 1 'llJ

ILoC cl X Ts ,, "'l I Z :1,J u s Ir I l"4 X T

1200 C s ti r. l X T

1170 11 u s j~OA l T LEGEND ., Tl 140 II JS i! l

I) ,,,i T1 11 v I SN l FULLJudd IC s * iH::l T

J05v IC s "llf l T ~ §YMBOLPARAMETER 4 1020 IC SN ~ TJ( * (Turb) JO cm •13 sec-, El '190 ID s.. Xt l T ~

T Cjt,Q IC 5"')( d T (Oa) O. 5 ppm z" I '13 J IC SNX l t ~ r

T (NO, N01) 0. 2 ppm N,XT 900 ID SX"-l t e w u >i70 IO s 0" T I

., cso.1 0.1 ppm sD ~'tO ID SNX ce T......

1.0 l d I u ID s * tl ~ T Cb_l 10 X 10-•m-1 B 780 IC S* l E e T 7~0 IC ; l ~ F T (Temp) O • - 100 • C T* 720 I D s * l fl T"' b90 D s ,c, l ' tl I: T (Dew Pt) O • - 100 • C D

,I ooU S* x: l B f T s o3u S* X L b E Figure 3.3.8 Aircraft Sounding - 18 July 1979 l oOO SU/I, X t* ,1u s i;C t,. l BE

~ 4(J ,·" • C l C:

'> lO S I\X. C l l_ * 4~U ~ I\ X D l t T H 4'lu S I\ X C l f T 'l 42J SIii • C C T C

l'hl 'it, ~ l E T 3~0 <;" • C l F T ... ., lt; ·)S~ X l f T ~

jlJU 'I t: T t l711 l ~ f'"'S* T 24C \ ,\ X C F ~ T ,,ll C S r1 T I a J s ~. Ll 4 "' T 1-'H, (; l .. I"' . "

l d17) ', " . L ,. T

" ) • Ll 1 f T (J J l l ",;.

J() ,;: A L / I•, ,- T

- i ()- -- ------~)- - -- -- -- in--- - - --- '')- ------ - ) i) •• -- -- -- -- - ·-- - - ·1C)- - - -- - - - t,/)- ---- -- - 70---- ----~ ,)----- ··-- .. o- ---- -- )CC-(o ')-

~csct r,J LI fLLl '..l~L.

~

C0FPLT \fS ul ~~~ OJ oo--ou 13:Jo:19 ~A<.f

fATF: 1/ISl14 ~CLTr: l, Vf ·( p L. I I\ l LA"T"l~(t/PA~S: 617/ 4 TIM•': o:zc:ie To o.,i .. :., ~Ir.. GR(L~C tl~v.: 11~1~\ll

-10---------o--------10--------?C--------]0--------40--------~u--------b0--------7C--------80--------qo-------lCC l~OC IC S e ,,x l 1 I l 4 70 l C S o t l T I l44Ll 10 'i ~~, * l T 1410 I') S ,,,o, l I llijU IC S Ne,•E l T 13~0 ID ~ ci*f l 1 13~0 IC 5 ~P: ti< l 12'10 IC S tld l T,,. ,.

LEGEND1 l 01, l) s r l T u ,c 0 S "ij J( E l l llOO C S XH t l FULL" PARAMETER SCALE ]5YMBOLI I 7o S ",._ ~ » l T I l 41J ':i* E T z* (Turb) 10 ~m •ta sec-, E1110 s £ T l* * 10~0 s ~c *t T l (Oa) O. 5 ppm z I O'iO SN C t T l* (NO, NOx) 0. 2 ppm N,XIOlO S N 0 t ti X T l

~ 991) s ~. C *6 T l 1s0.1 0. 1 ppm s L 'lbl) ~ ~; u * f T l

10 X 10-6 m -iT •nu SN C i<* T l Cb-> B I ',IQU u H8 T l"s.. (Temp> o·-1oo•c TT 870 ~ E•3 T l

w u H'tO S N D T l I " (Dew Pt) 0" - 100 • C 0

0 810 S II i; X6t T l00

·~ ,.

t

0 t 7HO (J T ls " 751) s .. ~ T l* Figure 3.3.9 Aircraft Sounding - 18 July 1979 720 S C II liiX T l

M t,90 s (JI\ Tl bbO S IJ N b X t Tl o3D ~o tt l( E lT"' 5 1>00 SMl nx f ZT

L 5711 S I\C 8 X i * ~40 S ,, 0 •e t T l ,.'>11.J ~ C E T i. 480 s ,, r. X 6 F T l

.. ,a ~N C t\F T l

.. ,a ,, D •

~ T l

]Qt; S~ C X E ,I T l

UJiJ s ~ u IX n T L

HO s ~ IJ X E 'I T ·1cu 5 N C EX tl T l

uo \ ~ G ~ Xrl T l

/ 41) ~ ~ C Xii T l

?IC • rl·.1 1~. L Tl

l·l!.., ii -:; ·~ ,, • l f ,;; ,.ll 'JG '., ~ C *

ll•J J; ~ T ~ "' j•: '> C"' " .' ., ' ¢

I6.i l, l 1 .,;,JI.. lF T '

,J I-10---------J--------to--------,~--------~t;--------4J--------~•)--------L~--------,~--------d'l--------qo-------1cc

I

~[•Ct~T Lf F~ll ~C~lf

PA Lt IIU0--00 IJ:3o:l.,CUFPLl Vfk Ul M~O 03

L:A T··; 7/lt/P k ( Li Tr "1 ,, 1-' l I I, 1 .,.

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-10---------0--------10--------2a--------Jl---------.0--------~o--------oc--------10--------tu--------~o-------1cc 17101 I 1<>811 I I Io'><., I I cl ll I ,qu l -,o O LEGE:ts.'D l ~ 30 •~ou l47Ll 14 4t) PARAMETER

FULL SCALE SYMBOL

l4lJ !Hu 135U 1320 12Q(; I

(Turb)

(Oa)

(NO, NOx)

10 cm •ta sec-,

O. 5 ppm

O. 2 ppm

E

z N,X

w I co....

A L T I T u D

llnC 1230 12CG 11 7.J I I 40 I llO 1080 IO~J lOlO

I I IC IC

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X* NX f:I.\ ~. 1*

L Zt *

l

l l

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T r T T

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(SOal

(bK.. )

(T~mp)

(Dew Pt)

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o•- 100' C

0'-I00'C

s B

T

D

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bLl

JC ID

s s

e*" t. *X

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!Figure 3.3.10 Aircraft Sounding - 18 ,July 1979 -,30 111 s d* X l T

" 9(JU

rl7U JC ID

s s

Cl :;;.

X* t X

l l

1 T .., 84L IC s B r, * L r

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ill - I .')- -- - - - - - - ,,) - - - - - - - - 1 •J - - - - - - - - '- ) - - - - - - - - > :J - - - - - - - - •• \I - - - - - - - - "': i- - - - - - - - r,,; - - - - - - - - 1 1 - - - - - - - - ri, 1- - - - ·- - - - ·1 ·)- - - - - - - I ( +l

1> ~ r ( / 1\ f l. t f l, l l '.: ( tr, ( I

3,3,3 Tracer Test 3

Release Location: Livermore, Alameda County

Time and Date: 1510-2030 PDT, 7/18/79

Amount: 101 pounds of SF6 per hour

Release conducted during west-southwesterly winds (directed toward Altamont

Pass) of between 5 and 7 mps. Winds within the San Joaquin Valley were similar

to previous test

Initial transport into the San Joaquin Valley

The tracer was transported by the generally westerly winds at the release

site through Altamont Pass and into the San Joaquin Valley. The tracer was

first detected in concentrations as high as 103 PPT along Coral Hollow Rd in

the San Joaquin Valley during Traverse 1-1, conducted between 1658 and 1725

PDT. During Traverse 1-6, an essentially Gaussian plume with a peak of about

900 PPT 11300 PPT/lb-mole SF6 released/hr) was detected at about 1930 PDT along

Corrai Hoi iow Rd. Corral ~I low Rd. I ies directly east of Altamont Pass~

During Traverse 1-4 conducted between 1919 and 2045 PDT, SF6 was detected along

Interstate 5 between Gustine and Altamont Pass. The tracer was spread quite

uniformly (peak concentration of 83 PPT) over the entire distance of about 45

mi !es. The route probably traversed the western edge of the tracer plume. The

first evidence of a clear plume within the San Joaquin Valley was found during

Traverse 1-5 in which concentrations as high as about 440 PPT 1640 PPT/lb-mole

of SF6 released/hr) were found along Hwy 132 between 1-5 and Hwy 99. The

tracer concentration profile along Hwy 132 was broader than that detected

during the previous tests from Manteca due not only to the greater distance

traveled but also to the turning and divergence of the Altamont Pass flow as it

entered the San Joaquin Valley. Also during Traverse 1-5, which ended shortly

after midnight 7/19/79, SF6 was detected at about 20 PPT as far south as Hwy

140, west of Merced.

SF6 was detected at the Modesto hourly-averaged sampl Ing site beginning at

2100 PDT, 7/18/79. A maximum concentration of 215 PPT 1310 PPT/lb-mole SF6

released/hr) was detected in Modesto between 2200 and 2300 PDT. As shown in

3-82

Figure 3.3.11, SF6 was also detected at the west San Joaquin Valley sites of

Patterson and Gustine. A maximum of 198 PPT (290 PPT/lb-mole SF6 released/hr)

was detected at Patterson between 0100 and 0200 POT, 7/19/79. Low but non-zero

SF6 concentrations (about 20 PPTl were first detected at Patterson between 1800

and 1900 POT. Between 2000 and 2300 POT, low but non-zero levels of SF6 (10-15

PPTl were detected at Gustine.

Tracer detection during the night fol lowing the release

During the night of 7/18/79, SF6 was detected at 10-40 PPT over a wide

area on the northwest side of the San Joaquin Valley. There was a

concentration gradient between that portion of the San Joaquin Valley closest

to the Altamont Pass (as high as 458 PPTl to that region of the San Joaquin

Valley west of Merced and Chowchilla (10-80 PPTl. Due to the complexities of

the wind flow patterns between Livermore and that region of the San Joaquin

Valley west of Merced and Chowchilla, the tracer concentration profile was

highly irregular. Due to the timing of the release, the tracer was probably

I imited to a shallow layer of air close to the surface. During the night, the surface winds in the northern end of the San Joaquin Valley were quite low. At

Stockton, the winds in the lower 1000 ft were less than 2 mps during the 0100

PDT pibal and essentially calm during the 0300 PDT pibal. As would be expected

from the low wind speeds at Stockton, the hourly averaged sampling sites in the

northern end of the San Joaquin Valley detected SF6 throughout the night of

7/19/79. SF6 was detected continuously at Livingston between 0300 PDT and and

the conclusion of sampling at 1400 PDT on 7/19/79. 98 PPT was detected between

0500 and 0600 POT. SF6 was also detected throughout the night at Gustine and

Patterson, Some SF6 (as high as 59 PPTl was detected as far north as Modesto

between 0300 and 0700 PDT. During the evening of the release, SF6 was detected

at low levels c<10 PPTl as tar south as Fresno. A number of hourly-averaged

samplers and automobile traverses showed these levels. This may have been due

to carryover from the tests conducted 7/13/79 and 7/16/79. It was not possible

to estimate the amount of the carryover.

3-83

I­n. n. r, !D LL Ul L.J

SJV-3 7/18/79 - 7/20/79 ...._,.,.nr - _..

C:IUl<:J • ~ PAT1ERSONA4, I u 1,, I 1:--+! 1, ! 11 b ...1,.w.1....~, 1, 1 ! 11 I 11 I0 10'0 -: GUSTINE

0 I 1 • + · 1 I • • L • • I cCTr+:cH • l-, 1 I 1 1 L, 1 l 1 1 L 6+ 1 1 I 1 1 I 1 1 l ]00,

DOS PALOS

0 I • • I • • I + • 6 • 6 t::d H I • J , 1 w L, , I , : I : I , i I w +1 I • • I 100 - FIREBAUGH

0 1 , , 1 , , , , , 1 , t..Lw H L. , , , , 1 , 1 Li 1 , 1 , , H , , L1 , , , , , 1 6+ 1

100 - TRANCIUlLITY 0 / 1 f j I f / 1 1 I 1 f I I I I ! I I I f l l I N I I b / I f l MH bD l f I I '", I

250 - rfl MODESTO 0 I +1 l • • I • • I • .. b--c:t-l , • l : , I + , I 1 • I 1 1 I I t I I t I I t I : t I 1 1 I

100- ~ LIVINGSTON

0 Lr :+ • · I : 1 Lt-d ~ 1 : ''1 1 : I , • I • , I 1 • I 1 • I 1 , I , • I 100 ,--

MERCED Ii'! I , , I : ,1. l , : l : , I • LI • t I , , I , t I , t:L d L , I .,.,i,.,..1,.'+ I , , I : 1 I - I •

100 -CHOWCHILLA

01:·i·,'+:i•· 1 :·1,1lt1i·1 1 1 ! 1 1l,,l,,l,,!11!41l,•I 100,

MADERA ,.. I , , I • • I 1 1 L .., • 1 ! 1 1 I w- l I tA H 6 , I I hl 1 1 I 1 , I , , I , i I , 1 ! i.:; T I

100 ...-FRESNO

~ j f f I I I I I I I I I I I f I I f I f t j 1 +L~ I,, l I I J t I I I ,..1.i....1.,.,J,..41,.J.,...t I 100,

MODESTO RES 0 ',r-1 Li, I, LI u I 1, L, I, 1 L cJ +,I,, I,, I,, I,, I,, I,, I·· I

100 -MARIPOSA

0 L.1 , I , _.J 1 1 I • LI 1 1 I • 1 I : • I • .J • • I I t I • , I • • I • , I 1 • I , 1 I 1 1 I 100 ,--

O'NEALS 0 I j I I j j I I i ,to ! .. I LJ L,;.....,'7 u . I ; ; L 64 I I I I I I I I I I I II I I I

12 15 18 21 24 3 6 9 12 15 18 21 24 3 6 9 12

PACIFIC DAYLIGHT TIME

RELEASE LOCATION, 541 LBS AT LIVERMORE RELEASE TIME, 1510 PDT, 7/18/79

Figure 3.3.11

• INDICATES MISSING DATA ARROWS INDICATE BOUNDS OF SAMPLING PERIOD

3-84

SJV

3

I

...

1

Figure 3.3.12

INDICATES SAMPLER LOCATIONS

\.LAYfA&U'lt I k.~FT.

\ _;.'- l"'

*

/]); IS THE RELEASE SITE 3-85

--~

Tracer carryover into day following the release

Automobile traverses on the day fol lowing the release showed that the SF6

was spread over most of the San Joaquin Valley north of Fresno. During the

morning of 7/19/79, concentrations ·of 10-20 PPT were detected while during the

afternoon SF6 concentrations were genera! !y be!ow 10 PPT. The concentrations

detected during the day after the release were higher than those found after

the previous releases from Manteca. This was probably due to the late hour of

the release which reduced the loss and dispersion of the tracer during unstable

afternoon conditions and to carryover from the previous releases. Nighttime

wind speeds, at least in the extreme northern end of the valley, were also

lower than during the previous two tests. A mass balance estimate indicated

that about 600 lbs of SF6 could be accounted for in a rectangular area bounded

on the east by Hwy 99, on the west by 1-5, on the north by Manteca and in the South by Hwy 180. This estimate was made using an average concentration of 17

PPT (+/-10 PPTJ detected during Traverses 2-2, 2-3, 2-4 and 2-5 and by assuming

a 2000 ft mixing height. Due to the uncertainties inherent in this

calculation, the mass balance merely indicates that a majority of the SF6

released was detected within the San Joaquin Vai iey during the day after the

release.

Summary

During this experiment, the tracer was released from the Livermore Valley

during mid and late afternoon. High levels of ozone and other pollutants are

typically found in the Livermore Valley, possibly due to transport from the San

Francisco Bay Area. This experiment was designed to determine if these

pollutants represent a significant flux into the San Joaquin Valley. The

tracer was transported into the valley and, as might be expected from the

previous tests, was preferentially transported along the western side of the

valley. An overview of the tracer transport path ls shown in Figure 3.3.13.

Due to the late release time (1510 PDT-2030 PDT), the tracer was detected only

as far south as the region west of Chowchll la and Merced on the night after the

release. The late release time also increased the amount of carryover into the

subsequent day, as compared to the two previous tests. An amount equal to

3-86

·-

w I co ......

Cv,_,,-,,

hlCv6-/0

~ ~~ .._, ) --o---- ~C

! 1£LEA<f SllE - Ll'.!IDE I ,0

ICllll 0

MlllU

10 10

:~

(SJ~'

1000

'i~

~

ARROW POINT INDICATES OBSERVED TRACER LOCATIONS NUMBERS REFER TO HOURS AFTER RELEASE START (1510 PDT., 7/18/79)

Figure 3.3.13

essentially al I of the SF6 released could be accounted for within the northern

San Joaquin Valley on the day after this release. The majority of the tracer

detected on this day must have been due to the release made during this

experiment but it is also possible that a smal I amount of tracer remained from

either or both of the first two tests.

3-88

3.4 Test 4 25 July 1979, Reedley Release (1200-1700 PDT)

3.4.1 Meteorology

General

The synoptic meteorology of 25 July was again characterized by

ridging aloft over the southwestern states (Figure 3.4.1). Maximum heights at 500 mb were located over southern California with consequent warming aloft and atmospheric stabilization as reflected by the 850 mb temperature trends shown on Figure 2.2.1. At the surface a thermal trough

was established over the Central Valley resulting in an onshore pressure gradient. The skies were generally clear throughout the San Joaquin Valley. Visibilities during the test ranged from 15 miles in the northern portions of the valley to 10 miles in the south. In the Fresno vicinity, visibilities ranged from 10-15 miles. Surface temperatures were above normal for the time of the year. Maximum temperature reported was 107°F at Bakersfield.

Transport Winds

Low-level winds during and after the release are given in Table 3.4.1. Early in the release period the low-level winds were southwest, shifting to west or west-northwest by the middle of the release. Wind speeds remained relatively high during the night until the early morning hours.

The 1000-foot streamlines (Figures 3.4.2 to 3.4.4) reflect the moderately strong northwest flow throughout the valley during the night. The wind speed at 1000 ft at Fresno was 11.7 m/s at 23 PDT from the northwest. By 05 PDT, an eddy had formed in the southern part of the valley as shown in Figure 3.4.4.

Pibal winds from Cherry Gap (in the mountains east of Reedley) were re­solved into components parallel and perpendicular to the valley axis. The time

variations in the perpendicular component (Figure 3.4.5) can be used to delineate the diurnal variations in the upslope-downslope flow. As shown in the figure,

a strong upslope flow developed after 11 PDT and lasted through 19 PDT. Maxi­mum depth of the flow was about 800 m. During the balance of the observational period the flow had a component toward the valley at all levels which masked any drainage flow that might have been present.

3-89

WF:DNESDAY, JULY 26, 1979

r-·-~------,, -- T T-- ,,-----, 1- ---~----'t\-,:~p

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SU'RfA([ WEATHER MAP. [-\Y· '\-: -" -'s...-~ ·- -- . ANn STATION W[ATHER :-\_: ~~- -~~- ~-'-- -- --- ---- ---AT 7 00 AM l Sf - - -- -

> .,,., ) ,<' J

Figure 3.4.1 Surface Weather Charts - 25 July 1979 (05 PDT)

Table 3.4.1

LOW-LEVEL WINDS 25-26 JULY 1979

Time Reedley Fresno (PDT) (Surface-100 m) (Surface)

25 July

09 144°/3.7 m/s Calm

11 191 /4.3

13 217 /2.2 240°/2.1 m/s

15 260 /4.5 240 /3.6

17 275 /2. 0 290 /3.1

19 254 /1. 4 300 /3.1

21 27 0 /3. 9 280 /4.1

23 330 /4.2 290 /4.6

26 July

01 320 /3.7 290 /4.1

03 300 /1. 0 290 /3.6

05 305 /0.9 Calm

07 087 /1.4 160 /1. 5

09 152 /1.8 220/2.1

3-91

... ·- .

,,-....._." -, ; ;.•a..:.. ~ l -< - ...,'

'- I \

Figure 3.4. l Streamlines - 25 July 1979 (15 PDT)2 1000 Ft-ag 3-92

---------

....

HM.I

0 C" <"

-~-~Jf-..-Jf , • . . . - - - --

------,

Figure 3.4.3 1000 Ft-agl Streamlines - 25 July 1979 (23 PDT) 3-93

.,..... ···"!!!!''·

111 --~ , .••111<. - ·• ......, .-..

. . . - - - -- ....... ,.

·-7

r

Figure 3.4.4 1000 Ft-agl Streamlines - 26 July 1979 (05 PDT) 3-94

11 13 15 17 19 21 23 i 3 5 7 9 81 /040

TIME (PDT)

Figure 3.4.5 Time-Height Cross Section Component Winds (m/s) From Cherry Gap25 July 1979 (Positive Component Represents Upslope Flow)

-4

-6"

2 790

2 520 ... _4

2250 ........ -6

E ~ 1980 Cl z :=i 0 1710c::

~ c:.!:l

w > 1440 0 c::, .... -4c:,:

::t: f- 1170 c:.!:l ...... u..J ::t: 896

612

313

-===~

-4

m/s

'- -4

Ur··\ '-J ~

-4

-2

3-95

-4

Mixing Heights

Aircraft mixing heights were measured on July 25 and are shown in Table 3.4.2. As noted in earlier tests, the mixing height over the slopes

tends to be somewhat greater (relative to the terrain) than over the valley itself.

Table 3.4.2

AIRCRAFT MIXING HEIGHTS JULY 25, 1979

Time (PDT)

Location* Mixing Height (m [above ground level])

1529 5 N Reedley 785 1603 23 E Reedley 645 (1370) 1735 6 NNE Grant Grove 1060

(* Distances in miles)

3.4.2 Air Quality

Regional Pollutant Levels

Maximum hourly concentrations of ozone are given in Figure 3.4.6. Numerous exceedances of the .10 ppm standard were observed in the north and east portions of the San Joaquin Valley. Concentrations of .15 ppm were measured at Modesto, Fresno and Bakersfield. All three monitoring sites along the Sierra Nevada slopes reported concentrations in excess of .10 ppm.

Maximum hourly concentrations for CO, S02 and NOx anywhere in the valley are listed in Table 3.4.3 together with the maximum hourly values recorded at the Rockwell International vans.

All hourly concentrations were relatively low with the exception of NOx at Modesto. Another unusually high value (.39 ppm) was recorded on July 24 at Modesto. Otherwise, no comparable values were observed during the month. The unusually high values suggest that the measurements may not be representative of a wide area around Modesto.

3-96

l

(

(

N I

s: "-1. t

0 C"

<"

"'d----=.!_~~ ..... .===o 7• ,o ~~ •

figure 3.4.6 Maximum Hourly Ozone Concentrations (~phm) - 25 July 1979

3-97

Table 3.4.3

MAXIMUM HOURLY CONCENTRATIONS JULY 25, 1979

Parameter Location Maximum Value

SD2 Bakersfield .02

CO Fresno-Olive 3.

NDx Modesto .32

SD2 Modesto (RI) < .01

SD2 Merced (RI) < .01

NDx Modesto (RI) .01

NDx Merced (RI) .02 _N_O..A--________M_ad ra RI) .01

Aircraft Sampling

In conjunction with the tracer release near Reedley, the airplane

sampled in the afternoon (1529-1920 PDT) downwind in the Sierra Nevadas. The

sampling route consisted of the following key elements: Three spirals; one in the valley near the tracer release

location, one in the Sierra Nevada foothills, and another

in the High Sierra region at the convergence of the South

and Middle Forks of the Kings River.

Three constant altitude downwind traverses parallel to the

Sierra crest at as low an altitude as safety would permit

and,

A traverse from the Sierra crest down the South and

Main Forks of the Kings River to the valley, descending

with the terrain at as low an altitude as safety would

permit.

Table 3.4.4 gives the overall pollutant characteristics measured on the

flight. Figure 3.4.7 shows the map of the flight patterns employed on July 25.

3-98

Table 3.4.11

AIR QUALITY MEASUREMENTS CARB SAN JOAQUIN JULY 25, 1979 SAMPLING

VALLEY PROJECT

Start Time PDT)

Location Point)

03 Mean Max (ppb) (ppb)

bscat Mean Max x10-6m-l)

S02 Mean Max (ppb) (ppb)

NOx Mean Max (ppb) (ppb)

NO

Mean (ppb)

Max (ppb)

1!,29 1 71 124 97 204 5 7 11503 2 85 112 140 218 4 6 1629 3-4 110 154 155 236 0 2 1711 5-6 102 127 137 234 0 2

w I

<D <D

1:735

lBlO

1B51

7

8-9

10-11

123

144

130

141

183

171

154

159

143

236

230

216

4

0

3

6

3

5

w I ..... 0 0

'=! ' 11 \J ~-~~ SAMPLING ROUT F'S

Fiigure 3.4.7

Aircraft soundings made during the afternoon of July 25 are shown in Figures 3.4.8 to 3.4.10, The sounding over the valley north of Reedley (Figure 3.4.7) shows a relatively well-mixed layer to 870 m-msl. Ozone concentrations

reached a maximum of .11 ppm in this layer. Another pollutant layer with much lower concentrations existed above 1230 m.

The sounding over the foothills east of Reedley (Figure 3.4.8) showed a well-mixed layer to 1620 m-msl but with a higher, mixed layer extending to 2300 m.

The break between these two layers corresponded to a shift in wind direction from the upslope flow to an easterly direction.

In the Kings Canyon (Figure 3.4.9) uniform mixing was evident from the bottom of the canyon at 975 m-msl to 2800 m-msl or roughly to the mean terrain height at that point. Within the mixing layer, ozone averaged about .13 ppm. Thus, the deep river canyons seem to be able to provide a major ventilating mech­anism for valley air. The traverses parallel to the crest would seem to support this conclusion as ozone bulges are evident over the canyons of the various forks

of the Kings River. The maximum mean ozone concentrations encountered during sampling were found on the 1680 m-msl traverse some 30 miles downwind from Reedley. Peak ozone levels were in excess of .18 ppm on that traverse. Over the High Sierra traverse between points 5 and 6, some 42 miles east of Reedley, mean ozone concentrations were still in excess of .10 ppb. The extent of the intrusion of polluted valley air into the mountains is well-defined by the east-west traverse down the Kings Canyon. Ozone concentrations rose to over .10 ppm within a couple of miles from the Sierra crest and increased to a maximum about 5 miles east of

the convergence of the South and Middle Forks of the Kings River (point 7), where levels as high as .17 ppm were measured. Thus, the maximum impacted area from the valley sources can be at substantial downwind distances.

3-101

c 1JcvL r " ..·'-' ut ,ii,..:.;n CJ 0O--no li:~1:0~ PAI,!-

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-1c---------o--------1u--------20--------Jo---------~--------~r--------bo--------10--------do--------so-------1c~ lt'ul G StK I T

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• 114\.I c~ d l T 111 o SCt ~ l T

l lll~U *c d l 1 T l 0~. O u * H l T 1 11.120 S* ~ l T

w T <;q(j *'-: e l T I l, 'ibll o l T"'~ ..... u 9311 U* K l T0

N C 90;, cSt ti l r LEGEND ~70 SL I'. t l T ~40 s C E u T FULL .. h l ll <; U ~ E L T PARAMETER SYMBOL~ 730 s ,) tl t l T ,, ,~o (Turb) 10 cm •t,. sec -i E~ C B1- l 1

> 72-> ~ C ~ lE T (0,.) 0. 5 ppm z l bQC, s C B .. 1

bbl, s u ~ l t T (NO, NO1) 0.2 ppm N,X ~3(1 s D e L E 1 cso.1 0. I ppm s ,iQ1) s 0 B l t T ;7() s u li a (b,..,) BT lOxl0-4 m- 1

j'tlJ s C B fl T (Temp) 0"-I00"C T,10 s C B cl T

4 (1 s .. l t (Dew Pt) o·-1oo·c D 4",IJ s u,i l " T .. l(J s 0 , * 3go 0 l~ T Figure 3.4.8 Aircraft Sounding - 25 July 1979" 3b0 s u d l I· 1

B,.J liO l ~ T

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-10---------J--------10--------20--------1~--------40--------~r--------~o--------10--------eo--------90-------100 Pt~(f"jT C,F FlJll 5CAU

PAl.:d ~JL--~u 12:47:04CLFPL l V':>< Ul MLJ·l 1.)j

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w I u l 77:J s ") b z T E

,..... J 114.J 5 i.; l T E LEGEND0 " I: 171U s C " L T Ew lb~O s L fl l T t

FULL lb5tJ s i; b H T PARAMETER SYMBOL

M lblO s C '\ L Tt ~E. 1l~~o s C E tl l T (Turb) 10 cm%, 11ec - E

1560 ; C ti -" (Oa) 0. 5 p,pm zs 1~3U s C D 'l T 1,

L !~OU s C fl l r f (NO, NOx) 0. 2 p,pm N,X1410 s D a l T E 1441) s D ll L T t 1s0.1 0. I ppm s J <, lu 5 C t1 l T E JO X 10-• :rn- 1(b,..,) BljijQ s i; ti l I f 1350 s D d l r E (Temp) o•-1oo•c T 1320 s (; ti l I E 12qc. s D 6 l T I: (Dew Pt) o·-1oo·c D

l2t>C s 0 l T t l230 s D 1 l I: T Figure 3.4.9 Aircraft Sounding - 25 July 1979 uo~ 'i D ~ z T E I 17u 'i C u l TE I l4u s r ~ l T 111 u s C d l T c ,10~1.l IJ fl l T r ,IL 5u C <l l T ,,1u>u s C l T , ,.s q(J n ti I T

':46,J ) u r, l ~30

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-10---------o--------10--------20--------10--------•o--------~u--------b0--------10--------ao--------qo-------1cc 24QI) I S C Te f, l I 24b0 I S C JT l /4i0 I S iJ •l T tl lo1tCv I Su fl L 2HU I SlJ I Ill l

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(Ca) 0. 5 ppm Z2010 s L -~ LT l

A 1q~o s L ll H l (NO, N0x) 0.Z ppm N,X l l <i'iU s C A '' l T 1 no s L * l (502) 0.1 ppm S I I ti9v s C t1 Tl t 10 x 10-, m -i B(b_lw T ldbU s C e Tl tc

I,__. u 1830 s C ~ Tl E (Temp) o·-1oo•c T 0 C 1800 s C B T l E .i:,.

E 1710 s G ~ T * (Dew Pt) 0 • - 100 'C D l74U s 0 Ii T j~ ':

1710 s 0 e " T l Figure 3.4.10 Aircraft Sounding - 25 July 1979 lbqU 5 0 ~ T l" ti q. ~~lt.5ll s u lt;20 s 0 ,1 Tl E" Es 15qo s ~ ~ Ti~

F.l l~bU s C ti ,)

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~c~C~~T c, FULL srALf

3.4.3 Tracer Test 4

Release Location: Reedley, Fresno County

Time and Date: 1200-1700 POT, 7/25/79

Release Amount: 97 lbs SF6/hr

Release conducted during afternoon westerly upslope winds. Surface winds at

the release site varied between about 2 and 5 mps during the release.

Initial upslope transport

During Traverse 1-1, conducted between 1430 and 1558 POT, SF6 was detected

in two locations along Hwy 63. About 8 miles east of Reedley, concentrations

as high as about 1100 PPT (1660 PPT/lb-mole SF6 released/hr) were detected. A

separate SF6 plume with concentrations as high as about 260 PPT were detected

northeast of Reedley. The release began at the onset of the afternoon upslope

flow, and the existence of two separate SF6 plumes was the result of the wind

direction variation as the flow developed. The plume detected directly east of

the release point was transported by the fully developed upslope fiow that

persisted until between 2100 and 2300 POT. SF6 was detected in the National

Forest and Park areas (Whittaker Forest and Grant Grovel beginning about 1730

POT-1800 POT. This corresponded to a mean transport wind speed of about 5

miles per hour. A maximum hourly-averaged sample concentration of 65 PPT (98

PPT/lb-mole SF6 released/hr) was detected at Whittaker Forest between 1900 and

2000 POT. No other fixed sampling site showed a significant SF6 concentration

during the evening of the release (see Figure 3.4.11). By 1830 POT, during

Traverse 1-5, a distinct tracer plume was detected along Generals Hwy between

Grant Grove and Lodgepole. The concentration profile detected during this

traverse is displayed in Figure 3.4.13. Also included in the figure is the

concentration profile detected by an airplane traverse through the same area.

Excei ient agreement can be seen between the tracer concentrations detected by

the airplane and automobile traverses. It is difficult to assess the crosswind

width of the tracer plume due to the tortuous nature of the traverse routes.

Based upon the airplane traverse data, the crosswind standard deviation in

concentration was between 3 and 4 miles (5-6 km). Grant Grove I ies about 30

miles (48 km) downwind of Reedley suggesting that the horizontal dispersion of

3-105

SJV-4 7/25/79 - 7/27/79

100 l ~ . WH l I 11\11.Cl'I:

0 1 I 1 1 +• • I H::OUb:Cb--b-fb , I t • H:::t I t t I w I 6-1 +t t I t I I FOREST

100 E LODGEPOLE 0 , I,,~ IL I I I J..,_ J L, [ ud I, w HI, It HH':I ,+,II,, I

100 E FRESNO

0 _, I f" 6 t..1 , , I , d /11:Hl:iw:tll-ll!'~.J!tl:lti.+ , I , , I , , I , , I , , I , , I .L..-d

100 li O'NEALS 0 L.Llu_lw.J. 1 I I f.J j / I I / / 6 L L ! I l J t!i / j I I 4 / I / / I / / I

100~ MADERA 0 .I.. I I L I I / / L l:fl:tll-~Ml!tt!'-1 ..J / / LJ / I / / I + / I I I I l / J

100 E CHOWCHILLA 0 1 I+, I 1 1 ) 1 1 L-Mi-, ) 1 t L..J i. L I 1 ..J 1 1 I , 1 µ , I 1 1 L+_Ll_.L.L LJ..JJ

t­ 100 l FIREBAUGHa.. a.. 0 ,l 1 1lHl1~,,l,,l,,4,l,,Lu.J ,.., (0 100 r Li.. ~ TRANQUILLITYUl

0 L I I~ 1 I 1 1 L I J 1 1 l c:L-.J..H l H I tf!'ftlf-.if-Bffu..4-LLLL.lLL1L-1

100 li HURON 0 .1.-LLLL l + , L I I 1 1 I u 1~J : 1 1+1 l 1 Ll.u..1.u.l.u.J

i00 E CORCORAN 0 LU ill L l t"' : L~ I 6--d--, l l H I h L b / ~~... 1:. l I / I \ ' I +d

100 [ ALPAUGH 0 Ll.ul.Li. I 1+I wd u I 1 1 J 1 1 L I I I u H I I t I 1 1 I I d 1 1 Lt+ I

100 Lu WASCO 0 tl..u.l..i.,ptliu-ii-.111-litt1t.t1t.l,.,HI-J,.tlt..J I hj I H µ I I t1t6tt11-~~j

100 rI BAKERSFIELD

0 i...ul L ilLL.p- · 1 t V:L\-J , , L ~ , , J , , L~ : I H ) u I t , I 1 1 l u.J 6 9 12 15 18 21 24 3 6 9 12 15 18 21 24 3 6

PAC!F!C DAY~lGHT ~:~E

RELEASE LiJCf~ !m,: 484 LBS 5c:-5 ,._, Rr~wL~V RELEASE TIME: 1200-1700 PDT, 7/25/79

Figure 3. 4 .11 * INDICATES MISSING DATA

ARROWS INDICATE BOUNDS OF SAH"''..ING PERI!J!l

3-106

SJV

4

Figure 3.4.12

• INDICATES SAMPLER LOCATIONS ~ IS THE RELEASE SI TE

3-107

SJV-4 AIR AND AUTO TRAVERSE COMPARISON 100

01::==--,4....-----L------1~--.......----L---~----' 0 2 4 6 8 10 12 14

STRAIGHT LINE DISTANCE ALONG TRAVERSE <MILES)

Figure 3.4.13

3-108

50

AUTO TRAV 1-5 7/25/79 1B23-191!12

AIR TRAV 1-3 FIRST HALF OF TRAV RT 7/25/79 1B11!1-1B21!1

the tracer corresponded to highly unstable conditions (Pasquil I-Gifford

Stabi I ity Class A or Bl. The rapid horizontal dispersion of the tracer was

probably due in large part to mechanical turbulence generated by the rough

terrain. In order to account for al I of the tracer released, the SF6 must have

been wel I-mixed over a height of about 600 m (about 2000 ft).

Transport during nightime drainage flow

After nightfal I, preferential cooling of the mountain slopes led to

drainage flows oriented towards the valley. The upslope motion of the tracer

was halted. At Whittaker Forest, the tracer was detected throughout the night.

Due to the flow reversal, a 5 hour tracer release led to an 18 hr impact at

Whittaker Forest. The concentration data collected at the hourly-averaged

sampler at Whittaker Forest is shown in Figure 3.4.11. Note that the tracer

concentrations detected at Whittaker Forest dropped to zero during the

subsequent afternoon upslope flow, presumably transporting the tracer out of

the San Joaquin Valley. Also included in the figure is the hourly-averaged

data collected at the other fixed scrnpl ing sites employed during the test. At

most sites within the valley, I ittle or no SF6 was detected. Note however,

that tracer concentrations as high as 31 PPT were detected between 0500 and

0900 PDT at Huron on the western side of the valley. The tracer detected at

this location was apparently transported across the entire width of the valley

by the combination of nighttime drainage winds on the mountain slopes and the

valley floor eddy structure referred to in the meteorological discussion.

Clearly, the nighttime drainage winds reduce the effectiveness of the daytime

upslope flow as a mechanism for ventilation of the valley. Since the afternoon

upslope flow is typically stronger and deeper than the nighttime drainage flow,

at least during the summer, the diurnal mountain-valley wind cycle does account

for a net flow out of the valley. As shown during this experiment, however,

I ittle, if any, of the tracer released into the upslope flow during the

afternoon was transported out of the valley by nlghtfa! !. After midday on the

day after the release, only low levels of tracer were detected in the San

Joaquin Valley. Either the second day of upslope flows were sufficient to

transport the bulk of the tracer out of the San Joaquin Valley or the tracer

was effectively dispersed throughout the valley.

3-109

Summary

During this experiment, the tracer was released from Reedley, a location

southeast of Fresno, during the afternoon. This test was designed to evaluate

the importance of the afternoon upslope flow on the overal I ventilation budget

of the San joaquin Valley and to quantify the impact cf val !ey po! !utant

sources on air quality on the western slope of the Sierra Nevada Mountains.

The tracer was initially transported upslope at an average speed of about 5

miles/hr. Good agreement between automobile and airplane traverse samples was

noted along and above Generals Hwy along the western slope of the Sierra Nevada

Mountains. The tracer concentrations detected during these traverses suggested

that the tracer was wel I-mixed to a height of about 600 m or 2000 ft. The

width of the tracer plume during these traverses was consistent with

Pasquil I-Gifford Stab ii ity Class A or B (highly unstable conditions) over flat

terrain. The enhanced horizontal dispersion of the tracer was probably due to

mechanically induced turbulence over the rough terrain.

As the afternoon upslope flow weakened and reversed during the evening and

nighttime hours, the upslope movement of the tracer was arrested. The 5 hour

release led to a measurable impact 18 hours in length at Whittaker Forest. The

tracer was also detected in fhe San Joaquin Valley during the night after the

release, indicating that at least some of the tracer was returned to the valley

by nighttime drainage flows. The tracer was detected as tar west as Huron,

about 45 miies southwest of the release site. An overview of the tracer

transport path ls shown in Figure 3.4.14.

It was not possible to estimate the amount of tracer remaining in the

valley on the day after the end of the release. Low concentrations of tracer

were detected over a wide area. As wi I I be made clear in the discussion of

Test 5, however, there is reason to believe that at least 25% of the tracer

released during this test remained within the valley during the night of

7/27/79, 2 days after this release. By considering the San Joaquin Valley as a

wel I-mixed tank, this loss rate corresponds to a mean residence time of the

tracer within the valley of just over 2 days.

3-110

WASCO

~ j 1£1..M SITE - lmlEY

C 10

ARROW POINT INDICATES OBSERVED TRACER LOCATIONS NUMBERS REFER TO HOURS AFTER RELEASE START 1200 PDT., 7/25/79)

Figure 3.4.14

3-111

3.5 Test 5 27-28 July 1979, Airborne Herndon-Chowchilla Release (2300-0215 PDT)

3.5.1 Meteorology

General

The major synoptic features of the meteorology on the morning of the

28th are shown on Figure 3.5.1. At 500 mb a weak short wave trough was moving

across the northern half of California, but not significantly influencing the meteorology in the San Joaquin Valley. Temperatures aloft over central

California remained warm as shown by the isotherms at 500 mb and also by the 850 mb temperatures at Vandenberg and Oakland plotted in Figure 2.2.1. At the

surface a thermal trough again developed in the interior of California. Sky

conditions on the 28th were clear and visibilities were generally good. Maxi­

mum surface temperatures were near normal with both Fresno and Bakersfield reporting a maximum of 100°F.

Transport Winds

The tracer release on 27-28 July was made by aircraft at a level of 400 m

above ground. The aircraft track was parallel to the wind, flying back and forth

between Herndon and Chowchilla.

The pibal winds from Madera were resolved into components parallel and

perpendicular to the valley axis. The parallel component was used to examine

the transport up-valley and is shown on the time-height cross section in Figure

3.5.2. From the cross section it can be seen that the night jet was established

at the time of the start of the elevated tracer release and that the jet continued for the release duration. Wind speeds averaged over 12 m/s during this period.

As shown by the 1000 ft streamlines at 2300 POT (Figure 3.5.3), flows

were northwesterly and roughly parallel to the valley axis through the length of

the San Joaquin Valley. The flow remained similar throughout the night. The

streamlines developed from the 0700 PDT data on the following morning show

cyclonic curvature developing at the southern extreme of the valley, signaling

the formation of the eddy which was fully developed by the next observation

time at 0900 PDT (Figure 3.5.4). By the 1100 PDT observation time (Figure

3.5.5), the "Fresno" eddy had moved north allowing the northwest flow on the

west side of the valley, which had persisted throughout the test, to diverge in

the southern end.

3-112

~ Cl 0...

Li> 0

>, ..... :, 'J

00 N

Ill...., s... re, .c u s... QJ .c...., re, QJ

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3-113

l

2 790

2520

2250

E ~ 1980 0 z

0 :=,

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I- 1170::c C!l ...... u.J ::c 896

612

313

0

0

4 ~

8 -..,,

~~' 4

=-----2

2

6

10 12

23 1 3 5 7 9 23

TIME (PDT) 81/041

Figure 3.5.2 Time-Height Cross Section Component Winds (m/s) From Madera 2i-28 July 1979 (Positive Component Refers to Northwesterly Winds)

3-114

t

c--

, ~ N I

SUll,I

-~-'! If 'f ' •• . . . - . . --.. ,. ,.. ....... -·· ' ,, - .-..

....... ~..

Figure 3.5.3 1000 Ft-agl Streamlines - 27 July 1979 (23 PDT) 3-115

I

C'

.._.... ' s,a&.t

•-• C , !'f tf f la

I.JI .......

. . . - . - -- ..,,

r

Figure 3.5.4 1000 Ft-agl Streamlines - 28 July 1979 (09 PDT)

3-116

( ....

-0

•Ut.l

-~., ! 1f ' ••

. . . - - - -. Figure 3.5.5 1000 Ft-agl Streamlines - 28 July 1979 (11 PDT)

3-117

Mixing Heights

No sounding data were obtained from the aircraft flights. Maximum

m,x,ng heights derived from the pibal wind data ranged between 1200 m and

1500 mat Fresno on July 27 and 28.

3.5.2 Air Quality

Regional Pollutant Levels

Maximum ozone concentrations throughout the valley on July 27 are given

in Figure 3.5.6. Highest observed concentration was .11 ppm, measured at the

Rockwell International van near Modesto •• 10 ppm was the highest value recorded

at any of the CARB sites.

Maximum hourly concentrations of other pollutants in the valley on July

27 are given in Table 3.5.1. All values were rather low, indicating a relatively

clear day in the valley.

Table 3.5.1

MAXIMUM HOURLY CONCENTRATIONS JULY 27, 1979

Parameter Location Maximum Value

S02 co NOx

S02

NOx

NOx

Bakersfield Bakers field

Bakersfield

Merced (RI)

Modesto (RI)

Merced (RI)

.04 2. .27

< • 01 .03

•02

3-118

(

N I

C"

0 C"

<".., -z.

1~-UI

ID~ -~-~~--~--:::3' l• ~ -:x:=:::::,:-·-=

• O ID to JO Cl wo• - --' .....

( Figure 3.5.6 Maximum Hourly Ozone Concentrations (pphm) - 27 July 1979 - 3-119

3.5.3 Tracer Test 5

Release Location: Airborne - from Herndon to Chowchi I la, Madera County

Time and Date: 2300, 7/27/79- 0215, 7/28/79

Release Amount: 67 lbs SF6/hr . +Release made into low=leve! Je,. Winds were northwesterly at about

12 mps in the jet.

Nocturnal Jet chracteristics

The nocturnal jet,which occurs frequently during the summer in the San

Joaquin Valley, is formed due to the decoupling of the stable surface layer

from the air aloft. The lack of surface shear stress al lows the air above a

few hundred meters in altitude to accelerate to velocities in excess of 10 mps.

The velocity profile typically goes through a maximum about a thousand feet

above the ground. The velocity profiles measured at Fresno by pilot balloons

are shown in Figure 3.5.7. Note that the 2300 PDT, 7/27/79, and 0100 and 0300

PDT, 7/28/79, velocity profiles are very similar. Note also that the veiocity

decays exponentially with altitude throughout the night (Figure 3.5.8). Only

the slope (or exponential decay rate) varies between the velocity profiles.

The later velocity profiles fal I off more rapidly than the first three. If the

atmosphere could be characterized by a constant eddy dlftusivity, the velocity

profiles might be expected to fal I as the square of the altitude. This

prediction is based on the analogy of flow in the nocturnal jet to the

steady-state problem of shear flow in a channel with paral lei boundaries with a

no shear stress condition at the lower boundary and a constant velocity layer

at the upper boundary. The deviation from the height squared law for the

velocity decay with altitude may be a reflection of the variation of eddy

diffusivity with height.

The presence of a high velocity jet just above the surface layer can lead

to a significant redistribution of pollutants within the valley during the

night. Pollutants that mixed upward during the afternoon could be efficiently

transported towards the southern end of the valley and detected at ground level

as the mixing height increased on the fol lowing day. This tracer release was

3-120

SJV-5 7/27/79 - 7/28/79 5000 -

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,. ,. ~ ,.

FRESNO

VISALIA

4000 -

3000 -

2000 -

1000 -

0 L1 18

...

... " 'I,

l,

\.

~ \. \. \. \. \. f'

l. I, 'I,

\,

\,

\.

~ ~ ~ \ t

24

',,

'-'-.. 'I,

' l. L

l... I

l, I, .. .. .. .. I,

'l. 1 l \. \,

;-. I

... .. .. .. .. .. .. •.. ... .. .. 'I,

• I 6

l, 'I, .. .. .. .. .. ..... .... ...... • .

'\, .. .. \. \. \. I. l l, ... ... .. •

\, ... ... .. .. l. l BAKERSFIELD l 1 1,

•• • T

12

PACIFIC DAYLIGHT TIME

Figure 3,5.7

WIND VECTOR WIND VECTOR

3-121

LENGTH SCALE ALIGNED WITH

- 1 CM• 15 MIS WIND DIRECTION

7

*

1

Hllll

"u w en en ' a: w I-w ~ ....,, 1121 w *C'iJJ ;;Ja.. ren

z ..... 3=

7

1· L

0 1000 2000 3000 4000

ALTITUDE (FT AGL)

Figure 3.5.8

3-122

NOCTURNAL JET VELOCITY PROFILES

FRESNO 7/27/79

• 230111 PDT 1 0100 7/28 3 030111 7/28 5 050111 7/28 7 071110 7/28

5000

designed to evaluate the effectiveness of this transport mechanism. The tracer

was released from an airplane flying in the high velocity portion of the

nocturnal jet. The airplane flew between Chowchi I la and Herndon throughout the

release. The tracer source could thus be approximately characterized as an

elevated, I lne source.

Transport towards southern end of valley

Automobile traverses detected 10-15 PPT of the tracer over a zone about 20

miles wide in the center of the valley. SF6 was detected at ground level along

both Hwy 180, west of Fresno and Hwy 198, west of Visa! ia. SF6 was also

detected at these same low levels at Tranquility as shown in Figure 3.5.9. It

appears unlikely, however, that most of the SF6 detected in these samples was

fran the tracer released into the nocturnal jet. The tracer was spread over a

length of at least 40 miles. 10 PPT SF6 in a volume measuring 20 miles in

width, 40 miles in length and 1500 ft deep accounts for a majority of the

released tracer (about 120 lbs). Yet during airplane traverses conducted on

the day after the release, concentrations as high as 75 PPT were detected aloft

at the extreme southern end of the San Joaquin Valley (see Figure 3.5.11).

Presumably, a majority of the tracer was transported into this zone. It is

also unlikely that such a large fraction of the tracer was transported rapidly

through the stable surface layer of air. A much more I ikely source of the

tracer detected in the center of the San Joaquin Valley is the release begun at

Reedley less than 60 hours previously. The tracer was apparently transported

back and forth across the center of the valley by the diurnally varying wind

flows. Due to the nighttime drainage condition, the carryover was detected in

the center of the valley. The estimate of the total mass of tracer detected

during the mid-valley traverses is about 25% of the tracer released during the

previous test. If al I of this tracer was from the previous test, which appears

I ikely, this loss rate corresponds to an characteristic time for exponential

decay (a mean residence time assuming good mixing within the valley) of just

over 2 days for the meteorological conditions that prevailed prior to this

experiment.

As mentioned in the previous paragraph, the highest concentrations of

tracer (except for a few Isolated samples) were detected on the day after the

3-123

l­a. a.. ,.., to LL. U) L.J

SJV-5 7/28/79 - 7/29/79 50 r-

~ CHOWCHILLA

0 p-d t::t::b-d ' d I I I 1 I I 1 I I , 1 I bl I , I I , I L "+ I , I I I I , , I , , I

50 r FRESNO

I

0 crl-cd-cd , t J..11:11:hu11:/ltht11:ttht11:~ 1 , I 1 , I , 1 I , , I , , I , , I 1 , I , , I 50 r

~ VISALIA

0 I, I l.;-ci I Lt:1 I 6-, I'd I+ I t:d ~ 1 j HI H 1,.' I'' I, I I 50 ..-,

~ FIREBAUGH

0 llt:±-0 Ln-J.11:1 Ltt1thtl!tt Li ,d r::td t:d od I "+ I I I ' ' I ' , I ' ' I 50 r-

~ TRANQUILLITYJ-:i,, ru, t:bd,,, rn,,,,,, LI .l..,.J m 1,, Li+,, 1,, 11 , 1,, 1 0

50 r ~ HURON

0 l,, lt4 6 r6, 1,, L, 6, 6, L, 1,, I,, I,, I,, I,, I,, I,, I 50 r

~ CORCORAN Lt, 1.p,-ru b-d,, 1, LI H 11 d H 1,,,,,,,, r,, 1,, r,, 1,, 1 0

50 r ~ ALPAUGH

0 l t , I.f=1 ' 1 1 l H I I t I 1 1 ) H 6.., b+-; I H I w I H I ••iit+ t i , 1 i t t i 50 ..-

~ DELANO

0 L, f I H Lo+, • ' • I LH--1 t-b J.-o Li I L-,1 Otttt11tlit,. I , , I , t I t , I

50 r ~ WASCO

0 L t If c:i-tt-J-.n J--rrL 1 I t::H I I L U 0tl.t11tt1tltt11:11 !.11ttt'-t I I I I I t t I

50 ~ BAKERSFIELD

••••• ' I I I I ·~ I I I I I

1 1 1 1 1 1 1 10 ;,t '~~~I 'i'2H 1~1~ ~1 ~~ I 3 , ~~.J '11dI tJ 1

1~ ~1 , 0

PACIFIC DAYLIGHT TIME

RELEASE LOCATION, 219 LBS SF6 AIRBORNE RELEASE TIME, 2300-0215 PDT, 7/27/79

Figure 3.5.9 • INDICATES MISSING OAT~

ARROWS INDICATE BOUNDS OF SAMPLING PERIOD

3-124

SJV

5

Figure 3.5.10 • nintrATC'<'.' <'.'AMl'll C'O I nrATTnllC'

1 IUJ 1 l.,M I L.J .JMnr LLI\ LUl.,M I 1 Ull.,)

~)'IS THE RELEASE SITE 3-125

SJV-5 AIR TRAY DATA COMPARISON

t­a.. a..

50r-, (0 ~ (f)....

AIR TRAV 1-7 1124-1137 7/28/79

0 --~~----~-----~---~-~----100

t- I a.. a..

r-, (0 50 ~ ~ (f) '--' '

I

~ )-J0 l I

0 3 6 9 12

TIME <MIN)

Fi gu re 3. 5. 11

AIR TRAV 1-8 1137-115e 7/28/79

3-126

release at the southern end of the valley. An average concentration of 29 PPT

was detected over the entire southern boundary of the San joaquin Vai iey at an

altitude of 1000 ft during Airplane Traverses 1-7 and 1-8 (Figure 3.5.11). The

tracer was apparently transported to the southern end of the val lay by the

nocturnal jet, but there appears to be no evidence of mixing downward by midday

of the day after the release. As the mixing height grows during the afternoon,

however, the tracer transported from the northern end of the va I I ey wi I I have a

chance to mix downward. No automobile or airplane traverses were conducted

during the afternoon to verify this.

Summary

During this experiment, the tracer was released into the nocturnal jet

which frequently develops above the San Joaquin Valley in the summertime. The nocturnal jet refers to a region of air with maximum velocities in excess of 10

mps. The velocity maximum typically occurs about 1000 ft above the surface of

the San Joaquin Valley. The jet apparently forms due to the decoupling of the

air aloft from the surface layer. The lack of shear stress at the surface can

lead to acceleration of the air aloft. This test was designed to evaluate the

nocturnal jet as a mechanism for transport of airborne pollutants from the

northern half of the valley to its southern end.

SF6 was detected at ground level west and southwest of Fresno. The amount ,....&. ~._.. .... ...,..,.,...,,,...4,, ro I o::::i.e.o..-1of SF6 detected within this zone was a majoiity UI Ille; OIIIVUIII I VIV\,.,I..>"""'-'• Yet

the concentrations detected in this zone (about 10 PPTl were an order of

magnitude less than the concentrations detected at the southern end of the

valley on the day after the release. Also, the winds in the nocturnal jet were

directed along the eastern side of the valley. The tracer detected southwest

of Fresno on the night of the release was apparently not from this release but

carryover from the previous experiment. The tracer released during this

experiment was apparently not detected at ground level on the night of the

release. As mentioned previously, tracer from this experiment was detected

aloft at the southern end of the valley on the morning after the release. A

crude picture of the apparent tracer transport path is shown in Figure 3.5.12.

The tracer was apparently stil I confined to a shallow layer about 1000 ft off

the ground. The tracer was probably detected at ground level only after the

3-127

'•I l'ALI• • ID ••.....

~ SITE - ~nm TO OOOHUA •• IO TAFT

ARROW POINT INDICATES OBSERVED TRACER LOCATIONS NUMBERS REFER TO HOURS AFTER RELEASE START (2300 PDT., 7/27/79)

Figure 3.5.12

3-128

mixing height increased to above the level of the tracer al lowing fumigation of

the tracer to ground level.

3-129

3.6 Test 6 30 July 1979, Pacheco Pass Reiease (1200-1725 PDT)

3.6.1 Meteorology

General

The synoptic meteorology (Figure 3.6.1) during Test 6 was character-ized by a region of high pressure aloft at 500 mb centered offshore of the

central-southern California coast. As reflected in the 850 mb temperature trend shown on Figure 2.2.1, the air mass residing over California remained warm and stable. At the surface, a thermal trough was established over the interior of California. A weak weather front off the Washington-Oregon coast was not affecting conditions in the San Joaquin Valley. Skies remained clear throughout the test. Afternoon visibilities in the valley ranged from 10-12

miles, although smoke was observed in the distance at both Stockton and Bakersfield. Surface temperatures were above normal for the date. Both

Fresno and Bakersfield reported maximum temperatures of 104°F.

Transport Winds

During the tracer release, pibal winds were taken on both the west and east sides of Pacheco Pass on alternating hours. The measured winds were resolved into wind components roughly parallel and perpendicular to the orientation of the pass. The parallel component was used to define the flux through the pass and is shown on the time-height cross sections in Figures 3.6.2 (a and b). The major feature of the cross sections is the low level convergence of the flow at the pass, i.e., the flow was directed toward the summit on both sides. This would imply that the tracer material would be carried aloft in the convergence zone. Within the valley, the afternoon flow at 1000 ft-agl is described by the streamlines on Figure 3.6.3. Northwest flow predominated throughout the valley with winds generally on the order of

3-5 m/s.

Mixing Heights

No aircraft sounding data were available during the release period. Maximum mixing depths in the San Joaquin Valley as determined from the pibal data ranged from 1000-1300 mat Los Banos and Fresno.

3-130

l­o 0..

en 0

O'>,-... O'> .....

..., 5,..

..i="' u 5,..

~ ..., QJ"'

3

QJ u

'+-"' 5,.. ::i

C.,")

...... I.O. M

QJ 5,.. ::i Ol·-LL

"' ;,-..J ;:, ....

3-131

0

(a) West Side of Pass (b) East Side of Pass

19 80 ,-1980 ~

u -4 - -)1710f- 1710

-2

1440 1440 - -~V, V,E

I E -~~ IE 11 70 E 1170~

~

I-I-:x:

<.!) :x: 896<.!)...... 896 ......w w:cw

I,_. :x: I -2 w N 612 612

-2

-4-3131 313 r

-2

13

HOUR

15 17

(PDT)

14 16 18

HOUR (PDT) 81 /060

Figure 3.6.2 Time-Height Cross Section of Through Pass Component of Wind at Pacheco Pass - 30 July 1979

(m/s)

....

, C'

..._ .•.·-. ' u.._r

e e C !! 'f tf' -Ip \• L_. .., •

. . . - - - -..

(

Figure 3.6.3 1000 Ft-agl Streamlines - 30 July 1979 (15 PDT)

3-133

3.6.2 Air Quality

Regional Pollutant Levels

Maximum hourly average ozone concentrations for 30 July 1979 are

shown on Figure 3.6.4. Numerous exceedances of California's ambient air

quality standard for oxidant were experienced throughout the valley.

Maximum concentrations (.14 ppm) were measured in the Fresno urban area.

Levels as great as .12 ppm were experienced at Whitaker's Forest in the

Sierra Nevadas.

Maximum hourly values of other pollutants in the valley on July 30

are shown in Table 3.6.1 together with maximum hourly concentrations ob­

served at the Rockwell International vans. Relatively low levels of all

pollutants were observed during the day.

Table 3.6.1

MAXIMUM HOURLY CONCENTRATIONS JULY 30, 1979

Parameter Location Maximum Value

S02 co NOx

S02

S02

NOx

NOx

NOx

Oil dale

F resno-01 i ve r_ .... ..,_,.. f'\14 .,,,, r r.t:::>11u-v 1 1 v-c;

Modesto (RI)

Merced (RI)

Modesto (RI)

Merced (RI )

Madera (RI)

•07

5.

.18

.01

< • 01 .02

.02

< • 01

3-134

l

(

(. Figure 3.6.4 Maximum Hourly Ozone Concentrations (pphm) - 30 July 1979

3-135

Aircraft Sampiing

The aircraft sampled in the late afternoon (1551-1911 PDT on

July 30 to provide (l aerial coverage of the tracer plume and (2 to

measure the flux of pollutants from the Santa Clara/San Benito Valleys into

the San Joaquin Valley. To this end, traverses were flown within the mixing

layer in the San Joaquin Valley, over Pacheco Pass, in the Santa Clara and

San Benito Valley and across the Diablo Range from Hollister to Mendota.

Spirals were flown on the east side and west side of the pass and over Fresno.

Although the data system failed to. record the meteorological and air

quality data, from observations and the strip chart recorder the following

comments are offered:

The top of mixing at Santa Nella Airport was 2700 ft-msl.

Some mixing was observed to 6000 ft-msl in the Santa

Clara Valley.

On the east-west traverse across the pass, ozone sharply

increased just east of Bell Station (near the summit

suggesting vertical transport and little exchange through

the pass.

Ozone levels in excess of .30 ppm were observed at 2500 ft­

msl over the South County Airport in the Santa Clara Valley.

Ozone levels dropped off sharply after leaving Hollister

Airport heading east over the Diablo Range suggesting no transport into the San Joaquin Valley at that time.

3-136

3.6.3 Tracer Test 6

Release Location: Pacheco Pass above Los Banos, Merced County

Time and Date: 1200-1725 PDT, 7/30/79

Release Amount: 99 lbs SF6/hr

Release was made into a convergence zone between a easterly fiow fru11 the San

Joaquin Valley and a westerly flow from the coastal side of the pass.

The majority of the tracer was not detected at ground level during the day

of the release. High concentrations of the tracer were detected only during

Traverse 1-1 which passed through Pacheco Pass and the release area. Low

levels of tracer were detected during other automobile traverses, notably

Traverse 1-2 and 1-3, but the levels detected during these traverses could not

account for more than a smal I fraction of the SF6 originally released.

Automobile traverses were conducted on both the east and west sides of Pacheco

Pass. During Airplane Traverse 1-3 tracer concentrations as high as 253 PPT

were detected. The tracer plume detected during this traverse extended for

about 8 miles with concentrations above 30 PPT. This traverse was about 600 ft

above the release height. This suggests that the tracer was carried aloft by

the flow convergence near the release site. The convergence of air at the

release site is consistent with afternoon upslope flows on both sides of the

coastal mountains that form the western boundary of the San Joaquin Valley.

At fixed sampling sites within the San Joaquin Valley, most sites showed

low, essentially background levels of tracer. The concentration data collected

at each of the fixed sampling sites is included in Figure 3.6.5. The

concentrations detected at these sites may be a smal I amount of carryover from

previous tests. Approximately 1240 lbs of SF6 was released in the San Joaquin

Va\ ley between 7/25/79 and 7/30/79.

Summary

The tracer was released from a pass through the coastal mountain range on

the west side of the San Joaquin Valley. The surface layer flow on both the

east and west sides of the pass were converging, indicating that the tracer was

carried aloft. Significant tracer concentrations were detected only during an

3-137

SJV-6 7/30/79 - 7/31/79

CHOWa-lILLA

CDt:t:c:-0 t::::6~11,,1,,111

FIREBAUGH

0jp 50 r

'

HURON~ t- 0 j pd o.J::O 6 6 d o-±:o I n:-q. , J a.. Q..

50 r .., co I tn u. ALPAUGH '-' ~

0 j +*•*b-Ot----r-~t:=bch*,*l 50,

! I

WASCO~ 10 j +cO..o:--CTb ~

50 1 8/IKERSFlEUl~

I

i I I I f7Hrfl:::rn*,*l*,*,*1*,*,*1*,*,*I*+ , l , I , i I ;0'+'''12 15 18 21 24 3 6 9 12 15 18 21 0

PACIFIC DAYLIGHT TIME

RELEASE LOCATION: 536 LBS SF6 AT LOS BANOS ~cLc~~c llMc: i200-i725 PDT, 7/30/79

Figure 3.6.5 3-138

SJV

6

.. 12' ___,, * -f"'""---""•-'-"I ·- ·-

' ·,

Figure 3.6.6

• INDICATES SAMPLER LOCATIONS <? '.~ IS THE RELEASE SI TE

3-139

airplane traverse conducted about 600 ft above the release site. It was not

possible to determine the transport path of the tracer after being carried

aloft. The tracer concentrations within the San Joaquin Valley were

indistinguishable from background levels.

3-140

4. Conclusions

1. The July 1979 field program was characterized by relatively

warm temperatures at 850 mb compared to average. All tracer tests were ~arried out under above average temperature conditions.

2. Average wind flow into the valley at Stockton and Los Banos

during July is directed from Stockton to Bakersfield at all hours of the day. The principal driving force for this flow is the thermal low pressure area to the east of the Sierras.

3. Average wind direction in the low levels at Visalia and Fresno for the July program was southeasterly during the early morning hours but northwesterly for the balance of the day. The duration of the southeasterly winds was longer at Visalia, associated with northward spreading of the Fresno

Eddy. 4. The Fresno Eddy develops during the night as a result of

stable conditions in the southern end of the valley. The absence of the eddy is associated with the passage of weak, cool troughs through the area.

5. As the eddy develops, the flow above Bakersfield and Visalia (from 1000 to 2000 m, agl) increases compared to the value at Fresno, indicating that some of the northwest flow is displaced upward and over the eddy.

6. The nocturnal wind jet formed to a significant degree during about half of the July 1979 data sample, Peak wind speed occurred at about 300-400 m (agl) at 2100-2300 PDT.

7. Mixing layer depths were observed to range from 600 to 1200 m during the afternoons when tracer tests were conducted.

8. Maximum ozone concentrations ranged between .11 and .17 ppm on the days when tracer releases were carried out.

9. Maximum CO values on tracer days were 2 to 5 ppm while NOx observations ranged between .18 and .32 ppm.

10. NMHC concentrations taken near Stockton averaged less than .2 ppm with iow concentrations attributable to automobile

sources.

4-1

11. The major components of the total particle composition

were silicon, sulfate and carbon. Crustal-like materials

accounted for the largest fraction of the mass.

12, Tracer released between 0700 and 1300 PDT on July 13, 1979 at

Manteca was transported by northwesterly winds along Hwy 99.

Approximately 40 miles south of the release site, the tracer

trajectory shifted westward and followed the San Joaquin

River, the lowest portion of the valley. Pollutants trans­

ported into the San Joaquin Valley from the California Delta

and San Francisco Bay area would also have been transported

along the western side of the valley on this day, minimizing

the impact of these plumes on the urban east side of the

valley. Based on a comparison to the Gaussian plume model, the dispersion of the tracer plume was consistent with neutral

or slightly unstable atmospheric conditions and a mixing depth

of about 1650 ft.

13. Tracer released between 1300 and 1900 PDT on July 16, 1979 at

Manteca was transported by northwesterly winds along the San

Joaquin River. As in the previous test, pollutants transported

into the San Joaquin Valley from the San Francisco Bay area

would have had a minimal impact on pollutant levels on the urban

east side of the valley. Based on a comparison to the Gaussian

plume model, both the horizontal and vertical dispersion of the

tracer was consistent with neutral or slightly unstable atmos­pheric conditions.

14. Tracer released between 1510 and 2030 PDT on July 18, 1979 at

Livermore was transported by westerly winds over Altamont Pass

and into the San Joaquin Valley. The intrusion of tracer into

the San Joaquin Valley was limited due to stabilization (and

comparative stagnation) of the atmosphere after nightfall~ On the day following the release, the tracer "cloud" was

transported down the western side of the valley in a manner

similar to that found during the previous two tests.

4-2

15. Tracer released between 1200 and 1700 PDT on July 25, 1979 at Reedley was transported upslope by the westerly afternoon winds, impacting sites in the National Forest and Park areas in the Sierra Nevada Mountains. The upslope movement of the tracer plume was arrested by the nighttime reverse flow. Some of the tracer carried downslope by the nighttime flow was was transported by flow across the valley floor to Huron on the western side of the valley. The afternoon upslope flow appears to be a mechanism for valley ventilation but its effectiveness is reduced by the corresponding downslope flow at night.

16. Tracer released between 2300, July 27, 1979 and 0215, July 28, 1979 aloft into the nocturnal jet northwest of Fresno was transported to the extreme southern end of the San Joaquin Valley by late morning on the day following the release. Essentially none of the tracer was transported to the ground level during the night of the release. Tracer detected at ground level west of Fresno on the night of the release was apparently carryover from the experiment con­ducted two days previously. The nocturnal jet appears to be

an efficient mechanism for transport to the southern end of the valley, but minimal ground level impacts occur until the surface mixing layer deepens during the following day.

17. Tracer released between 1200 and 1725 PDT, July 30, 1979 at Pacheco Pass west of Los Banos was carried aloft due to the convergence of a westerly coastal flow and an easterly valley uplsope flow. Essentially none of the tracer was detected at ground level within the valley.

4-3

ll~illlilllill~[l\111111105541