EPA-600/3-77-055
June 1977
Ecological Research Series
STUDIES OF OXIDANT TRANSPORT BEYOND
URBAN AREAS
New England Sea Breeze • 1975
Environmental Sciences Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
-------
!) RESEARCH REPORTING SERIES
v
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring • -
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
EPA-600/3-77-055
June 1977
STUDIES OF OXIDANT TRANSPORT BEYOND URBAN AREAS
New England Sea Breeze - 1975
by
H. Westberg, E. Robinson, D. Elias and K. Allwine
Air Resources Section
Chemical Engineering Department
Washington State University
Pullman, Washington 99164
Contract No. 68-02-2239
Project Officer
Joseph J. Bufalini
Atmospheric Chemistry and Physics Division
Environmental Sciences Research Laboratory
Research Triangle Park, North Carolina 27711
ENVIRONMENTAL SCIENCES RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
-------
DISCLAIMER
This report has been reviewed by the Environmental Sciences Research
Laboratory, U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the views and
policies of the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or recommendation
for use.
ii
-------
ABSTRACT
The relationship between sea breeze winds and ambient ozone concentrations
in two areas of southern New England is examined in this report. Air quality
along the Connecticut coast is strongly affected by a well developed sea breeze
because this system provides a mechanism for transporting the urban plume from
the New York City-New Jersey complex over coastal Connecticut. It is apparent
that air pollution control strategies for southern Connecticut must recognize
the advection of pollutants by the sea breeze. In the Boston area, sea breeze
situations are not as common or as extensive as observed along the Connecticut
coast. Arrival of the sea breeze at a Boston area station was usually associated
with a decrease in ozone concentration. Data used in this analysis was collected
during the summer of 1975.
iii
-------
PREFACE
During the Summer of 1975, Washington State University participated in
an extensive air pollutant monitoring program in New England. Primary ob-
jectives of the field program were to monitor ozone and ozone precursors
over specific parts of the New England region and determine to what extent the
oxidant problem in the Boston area is attributable to transport. Specific
topics to be considered included: (1) oxidant formation and transport within
the Boston and New York City urban plumes, (2) oxidant behavior in relation to
high pressure systems, (3) coastal Seabreeze effect on oxidant levels, (4) re-
lationships between ozone layers aloft and temperature inversions, and
(5) ozone transport in^the Connecticut River Valley. The field study, which
began on July 15, involved research teams from Washington State University
(WSU), Battelle, EPA-Research Triangle Park, EPA—LAS VEGAS and EPA—Region I.
In a previous technical report we provided a tabulation of the data col-
lected by WSU during the six week sampling period. The purpose of this manu-
script is to provide an analysis of pollutant behavior in relation to sea
breeze winds in the metropolitan Boston area and along the Southern Connecticut
Coast.
i v
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CONTENTS
ABSTRACT 111
PREFACE iv
FIGURES . vi
TABLES ..... viii
ACKNOWLEDGMENTS ix
1. Introduction . 1
2. Summary and Conclusions 4
3. Experimental Methods 7
4. Results and Discussion 9
Sea Breeze Effects in the Greater Boston Area 9
Sea Breeze Effects in the Groton, Connecticut Area ... 31
REFERENCES 51
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FIGURES
Number Page
1 General features of a sea breeze wind system .......... 2
2 Location of surface wind ( «^ ) and ozone stations
in Boston Area ........................ 10
3 Surface ozone concentration (ppb) in southern New
England at 1500 on July 27, 1975 ............ ... 19
4 Surface winds in southern New England at 1500 on
July 27, 1975 ........................ 19
5 WSU aircraft flight path on the afternoon (1450-1755)
of July 27, 1975, with ozone concentrations (ppb)
marked at specific points along the route . . . . ...... 20
6 WSU aircraft flight path on the afternoon (1200-1440)
of August 2, 1975, with ozone concentrations (ppb)
marked at specific points along the route .......... 23
7 WSU aircraft flight path on the evening (2035-2320)
of August 2, 1975, with ozone concentrations (ppb)
marked at specific points along the route ......... . 24
8 Surface ozone concentrations (ppb) in eastern
Massachusetts at 1400 on August 13, 1975 ........ . . . 29
9 Map showing Groton study area ................. 32
10 Battelle aircraft flight path on afternoon (1400-1530)
of July 22, 1975, with ozone concentrations (ppb)
marked at specific points along the route .......... 36
11 WSU aircraft flight path on the afternoon (1315-1555)
of July 22, 1975, with ozone concentrations (ppb)
marked at specific points along the route .......... 37
12 Surface winds in southern New England at 1500 on
July 22, 1975 ........ ................ 38
13 Calculated trajectory (Stanford Research Institute)
of air mass arriving at Groton, Connecticut, at 1700 on
July 22, 1975 . . ...................... 40
VI
-------
Number Page
14 Battelle and WSU aircraft flight paths during
morning hours on August 10, 1975, with ozone
concentrations (ppb) marked at specific points
along the route 43
15 Surface ozone concentrations (ppb) in southern
New England at 1100 on August 10, 1975 44
16 Battelle and WSU aircraft flight paths during
afternoon hours on August 10, 1975, with ozone
concentrations (ppb) marked at specific points
along the route 45
17 Calculated trajectory (Stanford Research Institute)
of air mass arriving at Groton, Connecticut at 1300
on August 10, 1975 49
18 Surface ozone concentrations (ppb) in southern New
England at 1300 on July 27, 1975 50
-------
TABLES
Number Page
1 WSU Ground and Aircraft Measurements 8
2 Meteorological Measurements at Logan Airport on
August 2, 1975 H
3 Surface Winds at Logan International Airport 12
4 Pibal Data from Boston, MA at 1309 on August 13, 1975 16
5 Ozone concentrations (ppb) at Coastal Stations in
Boston Area on Sea Breeze Days . 17
6 Hydrocarbon Concentrations (ppbC) Measured at JFK
Building on August 11, 1975 26
7 Ozone and Wind Data at EPA-RTP Chickatawbut Hill Site
on August 10, 12 and 13, 1975 27
8 Meteorological Measurements at Groton, CT on July 22, 1975 ... 34
9 Surface Data Recorded at Groton, CT on July 22, 1975 35
10 Surface Data Recorded at Groton, CT on August 10, 1975 42
11 Surface Data Recorded at Groton, CT on July 27, 1975 47
12 Pibal Data from Groton, CT at 1510 on July 27, 1975 48
VTM
-------
ACKNOWLEDGMENTS
We wish to thank the Environmental Protection Agency, Environmental
Sciences Research Laboratory, Research Triangle Park, NC, for financial sup-
port of this work. The guidance and technical advice provided by Dr. J. J.
Bufalini was much appreciated. We also thank the University of Connecticut--
Marine Sciences Institute for providing space and electrical power for our
laboratory trailer. Assistance by the EPA-Region I Air Branch is also grate-
fully acknowledged.
IX
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SECTION 1
INTRODUCTION
The sea breeze is a coastal wind that blows from sea to land. It is a
localized wind circulation pattern that is caused by the differential thermal
properties of land and water. During daylight hours, the land area along a
coastline is heated to a higher temperature than the adjacent body of water.
This creates a mesoscale low pressure cell over the land surface which causes
air movement from the higher pressure sea area toward the lower pressure land
area. Above the sea breeze there is often a compensating land-to-sea movement
that completes the cycle. Figure 1 provides a diagram of sea breeze charac-
teristics.
The sea breeze is half of the coastal diurnal wind cycle which also in-
cludes the oppositely directed nighttime land breeze. At night the sea is
generally warmer than the land and consequently the surface wind flow is
reversed and a land breeze is observed. The sea and land breeze cycles are
important air pollution distribution mechanisms in coastal regions because of
the regular diurnal nature of the process and its predominance over synoptic
weather patterns in many situations. A well developed sea-land breeze system
also provides the opportunity for a recirculation of pollutants since emissions
incorporated in the land breeze phase could be returned to the source area
after onset of the onshore flow.
As a meteorological phenomenon, the sea breeze has received considerable
attention since, on a small scale, it illustrates the principles which are
involved in the conversion of the sun's radiant energy to the kinetic energy
of atmospheric motions. Allusions to sea breeze type circulations have
occurred in writings since the time of Aristotle. A reference to a sea
breeze type circulation occurs in Aristotle's writings of approximately 350
2
B.C. Francis Bacon refered to the sea breeze as turning winds in his essay
-------
about wind in 1664. Much of the"early work in this century on sea breeze
3
circulations was performed by the Dutch and Germans, notably van Bemmelen
and Koschmieder who reported on land and sea breezes in Batavia and Danzig,
respectively.
RETURN
FLOW
CLOUD ZONE
ONSHORE FLOW
100- 1000 m
SEA BREEZE
FRONTAL ZONE
Figure 1. General features of a sea breeze wind system.
In the United States, there have been several studies of sea breeze pat-
5
terns along the Northeast coastline. Fisher conducted a sea breeze study
along the Connecticut coast near Block Island in 1960. Other studies of sea
breeze circulations include Frizzola and Fisher in 1963 at New York City;
Angell and Pack7 in 1965 at Atlantic City, New Jersey; and Raynor, Hayes, and
Q
Ogden along Long Island. Additional studies have been conducted on the West
q
Coast by Edinger and along the western shore of Lake Michigan by Lyons, Cole
-------
and Olsson. Since the sea breeze is dependent on temperature differences
between water and land it is not suprising that the occurrence and persistence
of a sea breeze are very dependent on meteorological conditions. Strong solar
insolation is a necessity as well as daytime temperatures that rise above
local water temperatures. Synoptic pressure gradients must be weak since
strong gradient winds will overpower the mesoscale sea breeze pattern. A sea
breeze is most commonly recorded during the summer months and especially dur-
ing periods when a high pressure system is centered over the coastal region.
12
Lyons has pointed out that no two sea breeze conditions are alike, but
they all have many similar characteristics. Under ideal conditions (i.e.
near zero gradient flow) the surface layer of onshore flow will vary in depth
from 100 m to 1000 m, wind speeds are in the range of 10-15 mph and the re-
turn flow layer aloft is about twice the thickness of the in-flow layer.
Wind speeds in the return flow layer aloft are normally less than 10 mph and
consequently are quite easily masked by synoptic winds. Typical areas covered
by the sea breeze are from 20 km seaward to 20 km inland.
-------
SECTION 2
SUMMARY AND CONCLUSIONS
Relationships between ambient air quality and sea breeze conditions in
southern New England have been examined in this report. Data employed in this
analysis were collected during July and August, 1975, by research teams from
Battelle (Columbus), EPA-Las Vegas, EPA-Research Triangle Park and Hashington
State University. Additional useful information was obtained from the Nation-
al Weather Service and the Massachusetts, Rhode Island and Connecticut State
ozone monitoring networks. This report concentrates on sea breeze—pollutant
interactions in the.-Boston area and along the southern Connecticut coast near
Groton.
In the Boston area, sea breeze conditions were observed on about 25% of
the days from mid-July until the end of August. The onshore flow was gener-
ally restricted to a shallow coastal zone. The sea breeze flow seldom pene-
trated inland as far as Norwood and Bedford (12 miles).
Sea breeze winds can have either a moderating or enhancing effect on
ambient ozone levels in the Boston area. It would be very difficult, how-
ever, to predict in advance which of these conditions would prevail on any
particular day. Probably the most common situation is for the sea breeze to
act as a cleansing mechanism for pollutants with lower ozone levels recorded
in the region covered by the marine air. This was generally characteristic of
the more vigorous sea breeze situations. On occasions when a weak land breeze
preceded the onset of a sea breeze, ozone concentrations at coastal stations
usually increased quite rapidly at about the time the onshore flow began and
then remained at a relatively high level for several hours. Evidence was pre-
sented which strongly suggests that on at least two occasions, sea breeze
winds contributed to a return of early morning Boston emissions to the city
later in the day. This transport cycle appeared to be restricted to a layer
-------
immediately above the surface. Sufficient data was not collected to document
recirculation aloft of contaminated air parcels within a sea breeze cell in
the Boston area.
In the Groton area of the Connecticut coast a well-developed sea breeze
wind pattern was an almost daily occurrence during the 1975 experimental pro-
gram. High ambient ozone concentrations usually coincided with a sea breeze
regime in this area. Aircraft flights over Long Island and the Atlantic Ocean
south of the coast showed clearly that the pollutants observed in the coastal
areas had been advected over the area by the sea breeze. The pollutants over
the ocean were part of the urban plume originating in the New York City -
northern New Jersey interstate area.
At Groton there was apparently one situation where the surface sea breeze
was linked with a compensating reverse flow aloft forming a potential closed
circulation cell. Such a situation could form a mechanism for the recircula-
tion of pollutants over a source area. However, this mechanism is considered
to be unimportant in pollutant distributions along the Connecticut coast com-
pared to the advection of the New York City urban plume.
The analysis of the Connecticut sea breeze situations showed that these
local wind patterns were much more important than "transport layer" (300-
1000 m) winds for explaining the occurrence of high ozone levels in the Groton
area.
It is quite evident that sea breeze situations in the Boston area were
not as common or as extensive as were observed during the same period along
the Connecticut coast. Although we have not carried out a detailed climatolog-
ical survey of the Boston area, the observed lack of a well developed sea
breeze is probably related to the nature of the synoptic weather systems that
moved through the area during the study period. Persistent gradient level
winds from the westerly quadrant hindered inland penetration of the sea breeze
in the Boston area. Along the Connecticut coast, gradient winds from the west
tended to cause the sea breeze to veer from a southerly to a more westerly
flow, but the sea breeze was not directly opposed as in the Boston area.
Air quality along the Connecticut coast is strongly affected by a well
developed sea breeze because this system provides a mechanism for transporting
the urban plume from the New York City - New Jersey complex into Connecticut.
Sea breeze - pollutant relationships in the Boston area are not as well defined;
-------
however, arrival of the sea breeze at a station usually was associated with a
decrease in ozone concentrations. It seems quite apparent that air pollution
control strategies for coastal Connecticut must recognize the advection of
pollutants by the sea breeze while in the Boston area this represents only a
minor feature with little probable impact on control strategies for the urban
area.
-------
SECTION 3
EXPERIMENTAL METHODS
Material used for this sea breeze analysis included meteorological and
air quality data collected in the New England region by Washington State
University, Battelle, EPA-RTP and EPA-Las Vegas during July and August of 1975.
Table 1 provides a summary of measurements made by the Washington State Univer-
sity group. The other three research teams monitored most of these same para-
meters. A detailed description of the program design, location of monitoring
sites and experimental techniques has been provided elsewhere .
Two other data sources provided valuable information: 1) National
Weather Service wind data recorded at coastal airports in New England; and
2) Massachusetts, Rhode Island and Connecticut surface ozone data obtained
from state monitoring stations.
-------
TABLE 1. WSU GROUND AND AIRCRAFT MEASUREMENTS
Ground-Level Measurements
Ozone Wind Speed
Oxides of Nitrogen Wind-Direction
Total Hydrocarbon Turbulence
Methane Dew Point
Carbon Monoxide Solar Radiation
Individual C^-Cg He Temperature
Halocarbons Vertical Temperature Discon-
tinuity (Acoustic Radar)
Aircraft Measurements
Ozone
Condensation Nuclei
Visual Range (Nephelometer)
Temperature
Relative Humidity
Navigational Parameters (VOR, DME, Altitude, etc.)
Bag/Can Samples (Hydrocarbons, Halocarbons, NO , etc.)
A
-------
SECTION 4
RESULTS AND DISCUSSION
SEA BREEZE EFFECTS IN THE GREATER BOSTON AREA
A careful analysis has been made of the meteorological and analytical
data from the study period to determine the characteristics and frequency of
sea breeze conditions in the Boston area. The presence of a sea breeze was
determined primarily from wind data at Logan International Airport. The
close proximity of the airport to the ocean permitted early detection of a
wind shift characteristic of an onshore flow. Wind data from inland stations
was used to document inland penetration of the sea breeze. Figure 2 provides
the indentity of surface wind stations used in this analysis. Moisture con-
tent of the air (dew point) and temperature were also used as an indicator of
onshore flow. A rise in dew point and decrease in temperature were normally
observed as the cooler and more moist marine air moved inland.
For example, on August 2, 1975 the sea breeze wind shift occurred at 1000
at Logan Airport. Temperature and dew point data for this day are listed in
Table 2. Beginning at 0600, the temperature began a normal daily rise. Be-
tween 0900 and 1000 the temperature decreased two degrees while the dew point
increased two degrees as the cooler and more moist marine air began to move
onshore. These meteorological changes then reversed as the sea breeze died
out at approximately 1700. In succeeding paragraphs we will point out various
general characteristics of the Boston area sea breeze. Specific examples
which illustrate how the sea breeze affects ambient pollutant levels will also
be provided.
General Meteorological Features. Assessment of the wind data from Logan
International Airport and the surrounding wind stations indicates that the
sea breeze was not a frequent occurance in the Boston area. Over the six week
-------
BEDFORD
•
HANSCO
MASSACHUSETTS
BAY
SCALE
l"=4.8mi
Figure 2. Location of surface wind (-<+-) and ozone stations in the Boston
area.
10
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TABLE 2. METEOROLOGICAL MEASUREMENTS AT LOGAN AIRPORT ON AUGUST 2, 1975.
Time
0400
0500
0600
0700
0800
0900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
Wind
Direction
deg
320
320
320
320
330
350
130
140
140
160
130
120
130
100
290
280
Wind
Speed
mph
9
10
10
9
7
7
4
4
5
5
5
7
6
7
8
10
Temp.
deg
84
84
85
88
91
94
92
93
97
100
101
98
96
98
99
98
Dew
Point
deg
70
70
70
70
70
69
71
71
70
70
69
68
68
66
65
66
sampling period only ten days can be readily associated with a sea breeze.
Table 3 lists Logan Airport surface wind data between the hours of 0700 and
2000 for the period July 15 - August 24. The tabulated data show the direction
from which the wind is blowing in 10° sectors and the wind speed in knots, e.g.
0905 means wind from 90° at 5 knots. The days of July 22, 27 and August 1, 2,
9, 11, 12, 13, 16, 17 exhibit a wind shift that can be ascribed to the onset
of a sea breeze. These periods are blocked in Table 3 for easy recognition.
On sea breeze days the shift from offshore to onshore flow normally
occurred about 0900 at Logan International Airport. A return to westerly
flow was always observed during the evening hours. It should be pointed out
that all the general features mentioned thus far apply mainly to the immediate
coastline area around Logan Airport. Quite often the marine air moving as a
sea breeze front did not penetrate far enough inland to be recorded at more
westerly wind stations. Only on three of the ten days was a sea breeze wind
shift recorded at Bedford (Hanscomb Airport), 12 miles inland.
The relative infrequency of a coastal sea breeze regime in this area is
probably due to an interaction between the onshore sea breeze flow and the gen-
erally offshore flow of the gradient or synoptic pattern winds. Longer term
11
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TABLE 3. SURFACE WINDS AT LOGAN INTERNATIONAL AIRPORT
IN3
Time
0700
0800
0900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
7/15
2110
2013
2015
2017
2215
2214
2318
2415
2112
2314
2211
2012
1909
2010
2109
2209
7/16
1909
2312
2310
2510
2510
2612
2412
2012
2012
1914
2014
1911
2210
2113
2212
2212
7/17
2411
2514
2612
2512
2611
2311
2412
2213
2314
2515
2314
2215
2211
2110
2313
2412
7/18 7/19 7/20
\
2506 2513 2008
2509 2513 2208
2709 2416 2209
2510 2417 2311
2505 2518 2211
2609 2417 2210
2510 2415 2413
2411 2419 2410
2310 2318 2010
2410 2216 2412
1909 2219 2010
1807 1914 2016
2311 2016 1909
2108 2113 2013
2313 1914 2010
2413 2215 2208
Date
7/21 7/22 7/23
2521 3010 2809
2513 3208 2808
2611 3207 2706
2411 3305 2509
2710 2403 2408
2710 2604 2210
2811
2413
2516
2714
2810
2608
2408
2406
2609
2506
1009
1009
1107
1007
1208
1305
1204
1202
1202
0904
2508
2412
2410
2612
2412
2316
2411
2309
2007
2407
7/24
2309
2308
2209
1908
2311
2415
2315
1913
1814
1916
1918
2015
2015
2014
1913
1908
7/25
2211
2213
2213
2412
2413
2413
2409
2212
2413
2414
2313
2312
2212
2413
2710
3113
7/26 7/27
2910 1202
3011
3013
3312
3412
2909
3013
2907
3008
3107
2906
3310
3407
0205
0601
0906
0905
0706
0907
0810
0911
1113
1113
1113
1216
1206
1209
1205
1104
1806 1703
-------
TABLE 3 (cont.)
oo
Time
0700
0800
0900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
7/28
2404
2307
2413
2413
2613
2413
2614
2414
2909
2410
2512
2410
2707
2607
2105
2408
7/29
2910
2911
3012
3308
3410
3511
3012
2911
2910
3206
3110
3011
3008
3504
3005
3305
7/30
2704
3006
2805
2104
2906
2907
1909
2212
2412
2707
2910
2513
2509
2508
2308
2308
Date
7/31 8/1 8/2 8/3
2808 0204 3209 3604
2909 0704 3307 3505
2909
2710
2709
2608
2911
3010
2710
1405
1306
1406
1607
1307
1306
1405
3112 2809
3110 2911
3507 0408
1304
1404
1405
1605
1305
1207
1306
1007
0908
0709
0412
0411
0312
0513
0414
0311
2910 2911 2906 0209
3307 2911 2810 0308
3205 2909 3008 0204
3006 2910 2905 0607
2805 3009 2905 0607
8/4 8/5 8/6
1007 2103 3510
0706 1404 0409
0807 1602 0411
0608 0605 0412
0708 1306 0709
1010 1108 0611
1010 1107 0810
0910 1111 0707
1110 1109 0607
1009 1107 0707
0909 0907 0907
0908 0705 0706
1107 0905 0507
1205 1204 0408
1203 3503 0608
1304 1001 0305
8/7
0414
0515
0416
0417
0415
0419
0416
0215
0212
0211
0111
3611
3409
3409
3409
3509
8/8
0207
0308
0412
0310
0414
0416
0316
0513
0108
3507
3605
3507
0105
3507
3506
3206
8/9
CALM
2906
2906
3206
3207
3105
1301
1407
1408
1307
1204
3009
2808
2608
2808
2807
-------
TABLE 3 (cont.)
Time Date
8/10 8/11 8/12 8/13 8/14 8/15 8/16 8/17 8/18 8/19 8/20 8/21 8/22
0700 2807 2502 3109 3204 2510 3310 0204 1404 2605 3111 3108 2805 2512
0800 2706 CALM 3103 3003 2606 3310 0104
0900 2908
1000 2708
1100 3106
1200 2812
1300 2809
1400 3209
1500 2710
1600 3012
1304
1304
0707
1208
1110
1111
1309
1307
1700 2910 2408
1800 2810 2707
1900 2810 2508
0803
0702
0909
0810
1007
1308
1206
1006
1405
1205
0705
1405
1605
1407
1507
1210
1209
1110
1408
1608
1707
2008
2710 3409
2407 3207
2909 3010
2711 2904
2913 2711
2719 3006
2715 3409
2815 3310
2912 3210
2811 3209
1004
0904
1203
'1305
1105
0405
1008
1310
1307
1208
2910 3107 1508
2000 2808 2510 2103 1909 2910 2905 1807
2100 2809 2409 3105 2008 2911 3506 2008
1801
1104
0905
1108
1309
0909
1209
0909
1107
1109
1108
0807
0906
0903
2707 3210 3109 3006 2514
2807 3110 3108 2505 2514
3010 3110 3308 2605 2715
2806 2910 3309 2310 2715
3010 2707 3108 3504 2715
3012 2812 2910 2007 2815
2913 2910 3010 2411 3316
2814 2810 3012 2213 3413
2814 2811 3013 2416 3414
2913 3010 3110 2313 3415
2713 2810 3111 2511 3416
3111 2909 2908 2508 3212
2912 2807 2806 2007 3210
2911 2806 2806 2008 3210
2200 3009 2407 0906 2007 2910 3404 2205 1504 2912 2806 2905 2008 3208
-------
wind frequency data for Boston do not show that winds from an easterly quad-
rant are a dominant aspect of the climatology. Increased surface roughness
and convective activity associated with the Boston metropolitan area probably
have little affect on the frequency of sea breeze occurrence. If anything,
these urban features might tend to increase the influence of the gradient wind
on surface layer flow.
Evidence of a closed cell circulation pattern, i.e. westerly return flow
aloft over the easterly sea breeze is lacking for the Boston sea breeze area.
Detailed wind trajectory data were not obtained and consequently recirculation
information must be gleaned from other less informative sources. The amount
of upper level wind data in the Boston area is very limited on the afternoons
when sea breeze conditions prevailed. Only on one day, August 13, was a pilot
balloon released that provided adequate wind aloft data. Table 4 shows that
there was a reversal in wind direction over Boston during the sea breeze per-
iod on August 13. In a classical sense this constitutes a return flow and
implies a circular wind pattern. However, this intrepretation and more impor-
tantly the possibility of recirculation of pollutants is complicated by the
fact that gradient winds were from the west. Consequently it is impossible to
determine what part, if any, of this westerly flow aloft results from sea
breeze recirculation. A more detailed discussion of this problem will be pro-
vided in the next section.
General Pollutant Features. The onset of a sea breeze can result in either an
improvement or a degradation in air quality depending on pollutant levels in
the air mass over the water. If the pollutant burden is high a deterioration
in air quality at onshore locations will be recorded as the sea breeze front
moves inland. On the other hand if the marine air is clean, air quality will
improve. Pollutant information in the Boston area that can be correlated with
sea breeze conditions is limited mostly to ozone data since the onshore flow
seldom reached the EPA-RTP monitoring station at Chickatawbut Hill where many
other gaseous pollutants were measured. In order to illustrate relationships
between the sea breeze and ambient ozone concentrations in the Boston area,
pollutant patterns on six sea breeze days will be discussed. July 27,
August 1, 2, 11, 12 and 13 were chosen for this purpose. The location of ozone
monitoring stations mentioned in the subsequent discussion are shown in Fig-
ure 1.
15
-------
TABLE 4. PIBAL DATA FROM BOSTON, MASSACHUSETTS AT 1309 ON AUGUST 13, 1975.
Height
(ft)
1000
2000
3000
4000
5000
Wind Direction
(degrees)
114
181
243
258
273
Wind Speed
(mph)
8
5
9
9
9
July 27, 1975 - Weather observations at Boston's Logan Airport showed a wind
shift to onshore flow by about 0900. Inland at Bedford the wind began to
change about 1100 but the sea breeze system was not clearly established at
this station until early afternoon. The easterly flow across the region per-
sisted until about 2100 at most locations around Boston. Table 5 lists hourly
ozone concentrations at Salem, Medford, Cambridge and Quincy on July 27. The
blocked time periods on each day mark the beginning and end of the sea breeze
period at Logan International Airport. Ozone patterns at the four coastal
stations do not exhibit unusual behavior on this day. With the exception of
Cambridge, ozone concentrations peaked about 1300 with a normal diurnal rise
and fall before and after the peak. Cambridge peaked somewhat earlier which
could possibly mean that the sea breeze provided a cleansing effect at that
station. Figures 3 and 4 show regional ozone and wind data at 1500 on the 27th.
The ozone pattern in Figure 3 supports a cleansing influence by the sea breeze
since stations in the coastal zone generally exhibit lower concentrations than
the more inland monitoring sites. The general ozone pattern in the Boston area
on July 27 is consistent with a southeast to northwest sea breeze flow that
brought cleaner air over the area and carried an "urban plume" to the northwest.
Aircraft data collected in an arc around Boston (Figure 5) showed ozone values
somewhat higher in the sector northwest of Boston, 70-79 ppb, compared to 50-
60 ppb in the southeast sector.
16
-------
TABLE 5. OZONE CONCENTRATIONS (PPB) AT COASTAL STATIONS ON SEABREEZE DAYS
7/27
Date and Station
8/1
8/2
TIME
0700
0800
0900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
S
19
[36
57
63
61
65
71
68
68
65
59
55
52
148
M
18
35
35
54
74
82
84
76
72
69
58
36
30
15
C
11
19
27
49
53
53
48
39
40
34
22
11
8
2
Q
40
351
54
56
71
79
81
72
62
65
67
58
45
38{
S
21
29
138
70
80
78
90
92
129
22
18
10
7
5
M
5
20
48
130
138
118
110
63
53
53
38
28
8
15
C
7
17
27
78
90
62
117
98
81
70
50
44
31
26
Q
25
33
651
99
90
65
54
155
1281
93
57
37
22
19
S
23
25
37
148
40
34
41
37
39
26
Ho
6
1
0
M
35
38
43
58
70
75
60
50
38
53
43
35
13
5
C
40
49
67
93
97
99
76
59
63
56
50
43
24
13
Q
42
55
106
1291
149
164
166
150
130
113
1021
69
11
1
S = SALEM; M = MEDFORD; C = CAMBRIDGE; Q = QUNICY
Blocked areas mark the beginning and end of Seabreeze period at Logan International Airport.
-------
TABLE 5 (cont.)
00
TIME
0700
0800
0900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
S
70
75
J74
65
32
21
1
8/1
M
6
17
140
40
88
98
103
115
93
38
50
40
40
30
1
C
11
22
31
30
57
50
43
63
62
67
73
72
53
58
Date and Station
8/12
Q
25
39
371
62
83
106
142
116
86
631
46
34
37
51
S
10
17
(26
34
38
46
54
56
50
37
49
46
136
14
M
13
20
28
40
50
75
70
70
60
50
38
25
13
0
C
25
27
43
65
50
44
31
26
31
19
17
26
27
1
Q
15
39
571
50
70
74
79
79
74
59
39
21
31|
6
S
0
9
130
54
54
52
52
50
51
49
52
156
48
28
8/13
M
0
11
33
60
50
58
65
55
40
40
33
40
18
25
C
4
9
34
30
30
31
25
25
49
52
45
59
44
39
Q
6
19
41 1
47
47
69
87
115
73
47
53
631
41
44
S = SALEM; M = MEDFORD; C = CAMBRIDGE; Q = QUINCY
Blocked areas mark the beginning and end of Seabreeze period at Logan International Airport
-------
0 10 20 40 60
Figure 3. Surface ozone concentrations (ppb) in southern New
England at 1500 on July 27, 1975.
Figure 4. Surface winds in southern New England at 1500 on July
27, 1975.
19
-------
NEW HAMPSHIRE
II
O LAWRENCE>
72
77
GLOUCHESTER
MASSACHUSETTS 7Q
79
WORCHESTER O 76
5
61
CONNECTICU
61
ATLANTIC OCEAN
Scale
l"= 2lmi
Figure 5. WSU aircraft flight path on the afternoon (1450-1755) of July 27,
1975, with ozone concentrations (ppb) marked at specific points
along the route.
20
-------
August 1 - A very interesting ozone pattern existed in the Boston area on
this day. Air quality at Salem appears to have been adversely affected by the
sea breeze. As shown in Table 5 the ozone concentration jumped from 38 to
70 ppb at the beginning of the sea breeze period. It remained high during the
late morning and early afternoon hours and then decreased dramatically from
92 to 29 ppb between 1400 and 1500. This is the same time sea breeze winds
dissipated at Logan International. Thus high ozone concentrations at Salem on
August 1 correlate very closely with the sea breeze period. Ozone behavior at
the Medford station resembled that at Salem. The sharp drop in ozone
occurred one hour earlier at Medford which is consistent with an earlier fall-
off in the onshore flow at a more inland station. The two more southerly
stations, Cambridge and Quincy, exhibited an ozone pattern that differed from
that just described for Salem and Medford. They showed a large increase at
the start of the sea breeze period but then air quality improved until the on-
shore flow ceased. A second ozone maximum followed immediately after the fall-
off in onshore flow at each of these stations. The second ozone peak occurred
one hour earlier at the more westerly Cambridge station.
These observations are consistent with the observed wind pattern and
its likely interaction with the Boston urban area pollutants. On August 1 the
winds were northwest and north until about 0700, when they began to veer
through east at about 0800 and took up a typical sea breeze direction of south-
east at 0900. Wind speeds were generally 5 knots or less from midnight on.
This pattern would have initially moved urban-area pollutants out over Boston
Harbor and nearby coastal ocean areas and then back over the land areas. The
ozone levels were highest in the Medford area, the station nearest Boston.
There is some indication in the Logan Airport dew point data that the air par-
cels contained in the initial sea breeze push, between 0900 and 1000, had not
been over the ocean areas very long because the dew.point dropped 2 to 3°F
with the wind shift to the southeast sea breeze. The easterly sea breeze flow
was apparently limited to a narrow strip along the coast and was not observed
inland at Bedford where the midday wind was westerly, the direction of the
general gradient flow. To the south of Boston at South Weymouth, the sea
breeze was from the northeast at 2 to 3 knots and was limited to a 2 to 3 hour
period around 1100. From 1300 to 1700 winds were westerly.
Ozone concentration had apparently increased rapidly in the air mass
after sunrise while it was over the water. This resulted in the large ozone
21
-------
jump observed as the marine air moved inland. The southeasterly sea breeze
flow resulted in greater fumigation of the most northerly stations and thus
ozone levels remained high during the entire sea breeze period at Medford
and Salem.
As the sea breeze flow broke down during the midafternoon hours, north-
westly gradient winds once again prevailed and moved the polluted air mass
lying to the northwest of Boston back across the city. Consequently, high
ozone levels were recorded at the two more southerly stations following
dissipation of the onshore flow. This then represents a case in which a com-
bination of gradient flow and sea breeze winds resulted in the transport of
urban emissions across the city twice in one day. It is also a situation
where there were enough pollutants in the land breeze cycle so that high pol-
lutant concentrations were recorded during the initial hours of the sea breeze.
August 2 - Ozone patterns on this day don't appear to reflect a sea breeze in-
fluence. Winds at Logan International show a sea breeze shift (Table 3); how-
ever, it is doubtful that the onshore flow penetrated inland to any of the
ozone monitoring stations. Winds at Beverly and Chickatawbut Hill were gen-
erally northwesterly and varied between 300 and 360° throughout the day. The
ozone pattern shown in Table 5 is consistent with a northwesterly gradient
flow. Quincy and Cambridge exhibited a higher ozone peak than the more upwind
stations near Medford and Salem. Flights conducted by WSU on this day verify
the southeasterly movement of the Boston air mass. As can be seen in Fig-
gures 6 and 7, highest ozone values were recorded in the Brockton area about
noon and then out over Cape Cod Bay during the evening hours. The one wind
station besides Logan which exhibited a sea breeze shift on August 2 was
South Weymouth, where winds were out of the east between 1700 and 1900. Ozone
levels at Quincy (near South Weymouth) showed a dramatic drop, from 102 to
11 ppb during this two hour period. While this is a time of day when ozone
levels are normally falling, this rapid of a decrease is unusual. It seems
that the marine air flowing onshore during this two-hour period must have con-
tained a very low ozone burden and consequently, helped to lower ambient con-
centrations at Quincy.
22
-------
NEW HAMPSHIRE
GLOUCHESTER
MASSACHUSETTS
WORCHESTER O §
(2000') 64
Q
(4000') 30
PUTNAM
(GOOd) 30
(4000") 30
CONNECTICU
(3000*) 32
PROVIDENCEQ L
RHODE
ISLAND
ATLANTIC OCEAN
Scale
I" =21 ml
Figure 6. WSU aircraft flight path on the afternoon (1200 to 1440) of August 2
1975, with ozone concentrations (ppb) marked at specific points along
the route. a
23
-------
NEW HAMPSHRE
../ O LAWRENCE
MASSACHUSETTS
CONNECTICU
49
ATLANTIC OCEAN
Figure 7. WSU flight path on the evening (2035 to 2320) of August 2, 1975,
with ozone concentrations (ppb) marked at specific points along
the route.
24
-------
August 11 - Judging from the ozone data in Table 5 and the wind data from
Table 3, the beginning of the sea breeze, about 0900 at Logan Airport, corre-
sponded to a degradation in air quality at near-by Medford. The maximum ozone
concentration at Medford occurred at 1400. The ozone pattern at Quincy, to the
south, showed a significant increase between 0900 and 1000, just after the
start of the sea breeze at Logan Airport, and a maximum concentration of 142
ppb at 1300. It appears that photochemical production of ozone began about the
time the sea breeze commenced and that ozone accumulated rapidly between 0900
and 1000 in air that moved with the sea breeze. The pollutants that were
involved in this early 03 formation had sources within a few miles of the mon-
itoring station because winds were very weak. Cambridge experienced an initial
ozone increase as the onshore flow moved through, then a decrease as cleaner
marine air fumigated the station. By 1400 the sea breeze began to dissipate;
and with the return to offshore flow, the more highly polluted inland air mass
was recycled through the downtown area. Ozone levels increased between 1500
and 1800 at the Cambridge station. The wind data from inland stations at
Bedford and South Weymouth did not show any sea breeze effect, so it is con-
cluded that the event was restricted to a narrow coastal zone.
August 11 is the only sea breeze day in which detailed hydrocarbon data
is available in the downtown Boston area. EPA-RTP conducted a diurnal study
of C2-C,Q hydrocarbons at the JFK Building on this day.. The diurnal hydrocar-
bon changes shown in Table 6 support the sea breeze analysis just proposed.
Hydrocarbon levels were high during the 0900 to 1200 period as the onshore
flow began, then decreased as the polluted air mass moved farther inland and
increased once again during the 1500 to 1800 period as the offshore flow
returned.
August 12 - The onshore flow penetrated farther inland on this day than on
most other occasions. Easterly wind shifts were recorded at both Norwood and
Bedford during the early afternoon hours. Since the onshore flow moved well
past the four coastal stations it is difficult to recognize any discernible
patterns from the ozone data provided in Table 5. If anything it appears
that the sea breeze, once again, served to lower afternoon ozone maxima at
Salem, Medford, Cambridge and Quincy on August 12. This hypothesis is based
on a comparison of ozone data recorded on August 10 and 12. A sea breeze did
not materialize on the 10th but otherwise meteorological conditions (wind
25
-------
TABLE 6. HYDROCARBON CONCENTRATIONS (ppbC) MEASURED AT JFK
BUILDING ON AUGUST 11, 1975
Hydrocarbon
Acetylene
propane
propene
i -butane
n-butane
i-pentane
n-pentane
toluene
ethyl benzene
xylenes
TIME
0600
0900
7.8
8.1
1.5
6.8
15.9
-
-
31.2
7.0
52.3
0900
1200
34.8
17.0
8.6
31.6
90.5
102.6
53.3
76.8
12.6
65.2
1200
1500
14.1
7.7
3.6
10.2
28.6
30.9
16.5
23.9
4.0
23.7
1500
1800
16.8
12.8
6.0
22.4
27.0
31.2
16.9
35.1
6.0
36.9
26
-------
TABLE 7. OZONE AND WIND DATA AT EPA-RTP CHICKATAWBUT HILL ,
SITE ON AUGUST 10, 12 AND 13, 1975
TIME
0100
0200
0300
0400
0500
0600
0700
0800
0900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
03
ppb
44
57
52
54
51
45
41
44
47
55
70
86
99
98
95
99
90
85
73
68
63
57
52
47
8/10
WD
Deg
290
290
290
290
280
290
300
300
300
300
300
300
300
300
300
310
300
300
270
280
300
300
290
300
WS
mph
7
7
7
7
6
6
7
7
5
5
4
3
3
5
5
5
4
5
3
6
5
5
4
5
- 03
ppb
58
45
43
81
47
51
46
29
26
45
59
78
104
97
98
102
97
74
57
45
38
55
61
39
8/12
WD
Deg
300
350
340
300
300
310
320
330
340
360
80
90
90
80
80
80
80
90
120
150
330
330
320
360
WS
mph
4
4
4
3
3
4
4
4
4
4
3
2
4
5
5
3
4
3
2
2
3
1
3
3
03
ppb
6
9
13
7
6
9
12
15
14
24
50
58
76
88
108
99
77
62
83
63
44
49
56
72
8/13
WD
Deg
300
320
330
340
340
350
350
350
350
60
90
90
360
240
270
260
270
240
230
220
240
240
250
220
WS
mph
1
3
4
4
4
4
4
3
3
2
3
2
1
3
3
4
3
3
6
6
5
7
9
10
27
-------
speed, temperature, solar insolation) were very similar on the two days. The
afternoon ozone peak at Cambridge on the 10th was 98 ppb compared to less
that 50 ppb on the 12th. At Quincy the recorded values were 124 ppb on the
10th and 79 ppb on the 12th. Thus the afternoon hourly ozone maximum was at
least 40 ppb lower at both of these stations on the sea breeze day.
August 12 was one of the few days when a sea breeze wind shift was re-
corded at the EPA-RTP Chickatawbut Hill site. Wind and ozone data recorded on
August 12 at Chickatawbut Hill are listed in Table 7. Data for the non-sea
breeze day August 10 are also shown in Table 7. It is obvious that there is
very little difference in the ozone pattern on these two days. During the per-
iod of easterly winds on August 12 ambient ozone concentrations reached approx-
imately 100 ppb. During the same time period on August 10 ozone levels were
in the 100 ppb range. Consequently it appears that the sea breeze had no
noticeable effect on ambient ozone levels at Chickatawbut Hill on August 12.
August 13 - Throughout the early morning hours of August 13th northwesterly
gradient winds moved Boston area emissions to the southeast. This plume began
to be diverted to the west following development of onshore sea breeze winds
at about 0900. Thus, the region to the south of Boston experienced the
greatest pollutant impact. Table 7 shows that the easterly flow was monitored
at Chickatawbut Hill between the hours of 1000 and 1200. Fumigation at the
Chickatawbut Hill site was manifested by a large increase in fluorocarbon-11
concentrations during this time period. Prior to the wind shift fluorocarbon-
11 levels were approximately 300 ppt. By 0920 the ambient concentration had
risen to 734 ppt and at 1000 to a peak of 908 ppt. The concentration then be-
gan to drop and was generally less than 300 ppt during the rest of the day.
Other primary pollutants showed a similar jump. The NO value of 65 ppb
A
(NO = 41; N02 = 24) at 1000 was the highest recorded on August 13.
As can be seen in Table 7 ozone remained relatively low during the sea
breeze period at Chickatawbut Hill but increased rapidly between 1200 and 1500.
Figure 8 shows that at 1400 a region of high ozone existed south of Boston ex-
tending from Quincy to Waltham. During the early afternoon hours on August 13
a change in the regional synoptic wind flow pattern occurred. Whereas on pre-
ceeding days gradient winds had been from the northwest they now shifted to the
southwest (Table 7). With the change to southwesterly flow the polluted air
mass that -existed south and west of Boston began to move in a northeasterly
28
-------
__.._.._ f
MASSACHUSETTS
SCALE" l"=l4mi.
ATLANTIC
OCEAN
45) / WEYMOUTH
PROVIDENCE f\
\/MARTHAlS
VINEYARD
Figure 8. Surface ozone concentrations (ppb) in eastern Massachusetts at
1400 on August 135 1975.
29
-------
direction across the city. This is reflected in the increase in ozone concen-
trations (25 ppb to 59 ppb) at Cambridge between 1400 and 1800 (Table 5).
Thus it is very likely that on August 13 emissions that left Boston during the
morning hours contributed to the ozone build-up south and west of the city
during the early afternoon and also caused an ozone peak during the early
evening hours in downtown Boston. A second late ozone peak near 2400 on
August 13 was not related to the Boston area sea breeze. The midnight peak
clearly resulted from long distant transport of ozone from source areas to the
southwest.
It is obvious from the preceeding analysis that it is very difficult to
make generalizations concerning sea breeze ozone relationships in the Boston
area. An even more troublesome task would be to try to predict in advance the
impact sea breeze winds would have on pollutant levels at various locations.
Probably more often that not, the sea breeze provided a cleasing effect with
ozone levels being lower than during comparable non-sea breeze periods. How-
ever, even at the stations closest to the coastline examples can be cited that
jeopardize this premise. The pollutant impact depends not only on sea breeze
variables but also on gradient wind flow before and after the period of onshore
winds.
Data obtained on August 11 and 13 suggested that sea breeze winds contr-
buted to a recycling of Boston emissions, or at least to a bimodal distribution
of concentration. In both of these cases the pollutant transfer was described
in terms of air mass movement at the surface with no mention of recirculation
aloft of contaminated air parcels within a sea breeze cell. In theory a sea
breeze recirculation cell aloft could provide a mechanism whereby an air parcel
that originated in the Boston urban area could be carried inland, lifted up and
sent seaward in the return flow aloft. The air parcel could then subside over
the water and be carried inland again. During this transport process photo-
chemically induced reactions could produce secondary pollutants such as ozone
in the contaminated air parcel. Upon its return to the Boston area elevated
ozone levels would be recorded.
As indicated previously, August 13 was the only sea breeze day on which a
westerly or possible return flow aloft was observed (Table 4). On this day
ozone concentrations were increasing at the Cambridge stations during the end
of the sea breeze period a fact that could possibly be ascribed to sea breeze
30
-------
recirculation. However, the alternate late peak explanation provided in the
August 13 analysis section seems more reasonable. Better documentation exists
for fumigation at Cambridge from an inland direction rather than an easterly
direction required of a closed cell sea breeze recirculation. Sufficient data
has not been collected in the Boston area to document recirculation aloft of
contaminated air parcels within a sea breeze cell.
SEA BREEZE EFFECTS IN THE GROTON, CONNECTICUT AREA
The relationship between Seabreeze conditions and pollutant levels in
the Groton area (Figure 9) is considerably different than that described
earlier for the Boston area. Oxidant precursor emissions are much lower in
the southeast sector of Connecticut than in the Greater Boston area. The an-
nual tonnage of hydrocarbons and oxides of nitrogen is about a factor of 10
lower in the Groton area. This means that recycling of pollutants in a sea
breeze circulation pattern would have less of an impact along the southern
Connecticut coast. However, in this region another important factor must be
considered. The New York City - New Jersey urban and industrial complex is
approximately 80 miles to the west which during the summer months is generally
in an upwind direction. New York emissions transported in an easterly direc-
tion definitely have a large impact along the Connecticut Coast. High second-
ary pollutant levels were commonly observed in this transported air mass
probably due in part to the fact that a majority of the trajectory was over
water where ozone scavenging sources are minimal. With transport wind speeds
of 10-20 mph the polluted air mass from New York had ample time to undergo
photochemical transformation before reaching coastal areas around Groton. As
will be shown, the sea breeze wind played a major role in moving polluted air
parcels from over Long Island Sound and the Atlantic onshore along the
Connecticut coast.
The sea breeze-pollutant interaction in this region of New England is
very similar to the situation along the western shore of Lake Michigan. The
work of Lyons and Cole has shown that pollutants emitted in the Chicago-Gary
region are transported in a northly direction over Lake Michigan. Following
onset of a lake breeze this contaminated air mass fumigates the Wisconsin
coastline and results in severe air quality degradation. Highest ozone con-
centrations were normally recorded between 60 and 90 miles north of the
31
-------
Scale: I = 3^ ml
INLAND SITE
DEVIL'S HOPYARD
NEW LONDON
GROWN
AIRPORT _
AILER SITE
(UNIV. OF CONN)
Figure 9. Map showing Groton study area.
Chicago source area. Along the Connecticut coastline wind directions are
different; however the transport mechanism is exactly the same. In the next
sections it will be shown that high ozone concentrations in the Groton area
can nearly always be traced to air masses originating in the New York - New
Jersey complex.
One important result from this detailed assessment of local winds along
the Connecticut coast has been a recognition that air mass trajectories based
on winds in the 300-1000 m "transport layer" differ considerably from trajec-
tories that take sea breeze winds into account. A review of calculated "trans-
14
port layer" trajectories indicates that pollutant fumigation occurred pre-
dominately from the northwest sector. However, ambient measurements clearly
show that ozone transport was the result of a sea breeze system moving polluted
air from the southwest. Thus, in most cases the source of the pollutant plume
32
-------
was the New York City area and not the area of Connecticut that was northwest
of Groton. The establishment of this important role of the low level, local
wind patterns is thus a vital one in understanding the causes of frequent
ozone episodes along the Connecticut coast.
General Meteorological Features. A detailed analysis of wind flow conditions
along the Connecticut - Rhode Island coast and in particular in the Groton-
New London area, showed that a sea breeze was a very frequent occurrence
during July and August. Similar criteria as described for Boston have been
used to define sea breeze conditions in the Groton, Connecticut area. How-
ever it was more difficult to characterize the sea breeze period from wind
data alone. Very seldom did sea breeze winds in the Groton area line-up
perpendicular to the coast. The onshore flow was normally from the south-
west, being the resultant of a pure southerly sea breeze flow, a Coriolis
rotation of the onshore flow and gradient winds from the west or northwest.
Other features such as an increase in wind speed and a decrease in relative
turbulence (steadying of the wind) were used to establish sea breeze time
periods. Temperature and dew point behavior were helpful for this purpose
as well. Table 8 provides a good example of the meteorological changes that
accompany a well established sea breeze at Groton. The beginning of the
sea breeze period at 1300 is clearly marked by a doubling of the wind speed, ..
a sharp reduction in turbulence (a.), a significant drop in temperature, and
8
a two degree rise in the dew point. On this day the onshore flow continued
until approximately 2000. As noted earlier, the sea breeze winds were from
the southwest direction (250-260°). A clearly definable sea breeze flow sel-
dome developed before 1000 at the WSU Avery Point monitoring site and on many
days it was 1200 or after before the onshore flow became fully established.
Wind speeds normally began to decrease about 1800 and by 2000 the sea breeze
had disappeared.
It was not possible to establish a generalized sea breeze penetration
distance from the data collected in July and August 1975. However, in the com-
prehensive meteorological study conducted by Fisher near Block Island the
shore flow was monitored up to 6 miles inland. Near New York City Frizzola
and Fis
inland.
prehensive meteorological study conducted by Fisher near Block Island the on-
v
and Fisher found that the sea breeze did not penetrate more than 25 to 30 miles
33
-------
TABLE 8. METEOROLOGICAL MEASUREMENTS AT GROTON ON JULY 22, 1975.
Time
0800
0900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
Wind
Direction
deg
CALM
CALM
CALM
260
265
250
250
255
255
250
255
260
260
CALM
CALM
CALM
CALM
Wind
Speed
mph
5
6
15
17
17
16
13
13
11
9
00
deg
6
7
10
20
13
8
6
5
6
6
6
5
5
10
23
14
8
Temp
°F
78
82
85
86
86
80
80
81
82
80
80
77
76
75
73
72
72
Dew
Point
°F
65
65
65
65
66
68
70
69
68
68
67
68
68
67
66
67
67
General Pollutant Features. High ambient ozone concentrations were frequently
observed late in the afternoon at stations in the Groton area. This was part-
icularily true on days when a sea breeze was present. Typically the ozone peak
occurred well after the start of onshore flow and during the period of de-
creasing photochemical activity. Since wind speeds in the sea breeze pattern
were usually quite strong (>10 mph) any local accumulation of pollutants would
have quickly been dispersed and consequently the most reasonable explanation
for the late peaks is advection of ozone-rich air from a distance source.
Air quality data collected in the Groton area on July 22 demonstrate the
onshore transport of a highly polluted marine air mass. Table 9 lists ambient
pollutant and meteorological data recorded at the WSU monitoring site near
Groton. As was pointed out in the previous section, meteorological changes
indicated a sea breeze start at about 1200 on the 22nd. Surface ozone concen-
trations climbed thereafter and remained high until the end of the sea breeze
period (^2000). Both WSU and Battelle conducted aircraft sampling missions
over southern Connecticut on the afternoon of July 22. These flights showed
very conclusively that the area of high ozone resided mainly to the southwest
34
-------
TABLE 9. SURFACE DATA RECORDED AT GROTON, CT ON JULY 22, 1975.
CO
CJ1
TIME
hrs
0100
0200
0300
0400
0500
0600
0700
0800
0900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
°3
ppb
67
48
33
29
24
27
30
32
44
46
55
59
78
118
121
111
112
105
104
90
72
54
48
33
NO
ppb
12
12
12
12
12
12
12
14
17
10
10
11
11
12
12
11
9
7
10
11
11
11
11
12
N02
ppb
15
17
22
19
21
21
17
21
18
14
13
12
15
18
14
15
15
15
15
14
18
22
15
24
NMTHC
ppm
.2
.2
.3
.5
.5
.3
.3
.2
.2
.2
.2
.2
.2
.3
.3
.2
.2
.3
.3
.3
.3
.5
.5
.5
CO
ppm
.8
.9
.9
.8
.8
.7
.8
.5
.5
.5
.5
.5
.7
.8
.8
.7
.7
.7
.7
.7
.9
.5
.5
.5
CH4
ppm
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.5
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
CFC13
ppt
255
315
355
350
310
265
290
330
280
210
185
185
350
500
390
310
260
210
195
255
310
285
385
360
W/S
mph
4
CALM
CALM
CALM
CALM
CALM
5
CALM
CALM
CALM
5
6
15
17
17
16
13
13
11
9
CALM
CALM
CALM
CALM
W/D
deg
235
270
260
265
250
250
255
255
250
255
260
260
ae
deg
12
15
13
15
14
10
7
6
7
10
20
13
8
6
5
6
6
6
5
5
10
23
14
8
RAD
mLy
0
0
0
0
0
50
500
750
900
1100
1275
1300
1075
1375
1250
970
700
430
175
45
0
0
0
0
TEMP
°F
73
73
72
71
70
71
72
78
82
85
86
86
80
80
81
82
80
80
77
76
. 75
73
72
72
DP
°F
70
69
69
68
66
65
68
65
65
65
65
66
68
70
69
68
68
67
68
68
67
66
67
67
-------
7
SPRINGFIELD
KINGSTON
MA
j PROVIDENCE
112
120
ATLANTIC OCEAN
N
Figure 10. Battelle aircraft flight on afternoon (1400 to 1530) of July 22,
1975, with ozone concentrations (ppb) marked at specific points
along the route.
36
-------
ATLANTIC OCEAN
N
SCALE- I=2IMI.
Figure 11. WSU aircraft flight path on the afternoon'(1315 to 1555) of
July 22, 1975, with ozone concentrations (ppb) marked at
specific points along the route.
37
-------
SCALE 0 10 20 40 60 80
III I I I
F*ORTLAND_
WORCESTER*
SPRINGFIELD
• READING
PHILADELPHIA
j
MD j
I
N
Figure 12. Surface winds in southern New England at 1500 on July 22, 1975.
38
-------
of Groton over Long Island and the Atlantic Ocean. Figure 10 shows the
Battelle flight path with ozone concentrations (ppb) marked at various points
along the route. It is obvious from this figure that ozone concentrations
were much lower over Connecticut than those recorded south of Long Island.
The WSU afternoon flight (Figure 11) showed ozone levels in the 90-180 ppb
range existing over the entire region south and west of Groton. This informa-
tion when combined with surface wind data at stations in the coastal zone
(Figure 12) leaves no doubt that the air quality degradation at Groton resulted
from onshore air movement. Furthermore, based on the aircraft data there is
little doubt that the contaminated air mass originated in the New York - New
Jersey metropolitan area.
For reasons that were cited earlier, it is interesting to trace the his-
tory of the polluted air mass arriving at Groton on the afternoon of July 22
based on wind trajectories. This task has been performed by Stanford Research
14
Institute with the results shown in Figure 13. The heavy line and numbers
show the route and travel time for the air mass arriving at 1700. It is ob-
vious that the place of origin does not agree with the source area established
earlier. In addition, none of the inland monitoring stations along this north-
west to southeast route exhibited ozone peaks in excess of 55 ppb on the after-
noon of July 22. Thus a trajectory prediction based on gradient wind flow
leads in this case and in most others we have examined to an erroneous air mass
history.
Before moving on to other examples it is worth noting the effect the
July 22 sea breeze had on pollutants other than ozone. Table 9 shows that no
discernable difference existed in oxides of nitrogen levels before, during and
after the sea breeze period. Likewise the methane and non-methane total hydro-
carbon concentrations show little or no change. Fluorocarbon-11 values appear
to rise somewhat at the beginning of the sea breeze period. The carbon monox-
ide concentration remained slightly elevated throughout the period of on-
shore flow. Thus with the exception of ozone, pollutant levels in the air
mass advected into the Groton area on July 22 differed very little from
regional background concentrations. This pattern is not suprising considering
the fact that the air mass had travelled nearly 80 miles prior to reaching the
monitoring station.
39
-------
-p.
O
Figure 13. Calculated trajectory (Standord Research Institute ) of air mass
arriving at Groton, Connecticut, at 1700 on July 22, 1975.
-------
Pollutant patterns on August 10, 1975 add additional support for the con-
cept of air mass transport from one part of the region to another. At Groton
winds were from the west northwest in the early morning and. then backed to the
west and west southwest at 0800. This wind pattern was the result of a west
northwest synoptic flow interacting with a southerly sea breeze condition and
brought a flow of ocean air over the Groton area. The marine origin was shown
by relatively high dew point temperatures in midday, a midmorning increase in
dew point as the sea breeze became established, and the relatively cool after-
noon temperature 80° even though the day was clear and sunny. An observed de-
crease in relative turbulence at Groton occurred during midday and this is
also characteristic of the sea breeze regime at this location Table 9 lists air
quality data-obtained at the WSU monitoring site near Groton on August 10.
A considerable amount of ozone data is available over the area on
August 10 as a result of the New England research program. Aircraft flights
over Long Island and the Atlantic south of Connecticut showed high concentra-
tions (>100 ppb) at 1000 ft. over both Long Island and the Atlantic before noon
(Figure 14). Most ground stations in Connecticut along Long Island Sound also
showed 03 in excess of 100 ppb at 1100 (Figure 15). Later in the day between
1630 and 1830, the time of WSU's afternoon aircraft flight, 03 concentrations
in the lower 1000 ft. over the Atlantic had risen to a range of 150 to 230 ppb
(Figure 16). Along the coast as late as 1700 there were still some ground
level values of over 100 ppb. At the WSU Groton site the 0, maximum was
especially late and reached 150 ppb in the 2-hour period including 2000 and
2100. At midnight the 03 concentrations was still 90 ppb.
The pollutant conditions observed on August 10 are a good example, once
again, of onshore transport of high pollutant concentrations as well as high 03
concentrations from an air mass that probably had its origin in the New York
City - Northern New Jersey interstate area. The meteorological situation was
favorable, obviously, both for the photochemical formation of excessive 03 in
the contaminated lower layers of the atmosphere and for the transport of this
polluted air mass inland across the Connecticut coast. This date was another
occasion when air mass histories based on regional wind trajectories differed
14
from our evaluation of a sea breeze transport. The trajectory ending at
Groton at 1300 on August 10 (Figure 17) moved out of the west northwest while
the coastal sea breeze and the New York urban plume came from the west
southwest,
41
-------
TABLE 10. SURFACE MEASUREMENTS AT GROTON, CONNECTICUT, ON AUGUST 10, 1975.
Time
(hrs)
0100
0200
0300
0400
0500
0600
0700
0800
0900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
03
(ppb)
40
13
13
16
18
16
18
29
36
52
68
93
110
113
103
100
108
130
115
150
150
130
116
90
NO
(ppb)
6
6
6
6
6
6
7
6
7
7
9
8
9
8
7
7
7
7
7
6
6
6
6
8
N02
(ppb)
20
30
27
20
18
15
16
13
13
20
18
16
17
19
15
15
20
17
29
22
23
22
24
25
NMTHC CO
(ppm) (ppm)
_ _
-
-
-
-
-
_ _
_ -
<.l .5
<.l .7
<.l .7
<.l .7
<.l .7
<.l .7
.2 .8
<.l .7
<.l .8
<.l .8
<.l .9
<.l .9
.2 1.0
.3 1.0
.3 1.0
-
014
(ppm)
_
_
_
_
-
-
_
_
1.7
1.7
1.7
1.7
1.7
1.7
1.7
1.7
1.7
1.7
1.7
1.7
1.8
1.8
1.8
-
CFC13
(ppt)
259
256
256
241
220
216
202
202
191
212
230
216
202
223
205
187
194
230
274
281
277
302
310
320
CC14
(ppt)
116
108
108
108
116
108
116
116
108
116
116
116
108
108
116
116
116
116
116
124
116
116
116
124
W/S
(mph)
4
5
6
5
4
4
7
6
8
9
13
17
16
15
16
13
12
10
7
9
4
3
6
W/D
(deg)
290
275
278
283
290
285
278
270
270
260
262
270
270
266
270
267
265
270
275
280
275
280
275
CALM
°e
(deg)
12
10
10
10
11
7
6
5
6
7
7
7
6
7
6
6
8
6
6
7
9
14
17
12
RAD
(mLy)
0
0
0
0
0
30
206
508
803
1023
1117
1285
1200
1275
698
850
500
180
74
24
0
0
0
0
TEMP
69
67
66
66
65
66
67
70
73
74
74
76
76
78
80
80
79
77
78
76
74
77
78
77
DP
63
62
60
58
58
59
59
60
63
64
65
65
65
66
62
64 .
64
66
64
66
67
66
66
68
-------
Figure 14. Battelle and WSU flight paths during morning hours on August 10,
1975, with ozone concentrations (ppb) marked at specific points
along the route.
43
-------
SPRW6FELD 95
0 10 20 40 60
Figure 15. Surface ozone concentrations (ppb) in southern New
.England at 1100 on August 10, 1975.
44
-------
Figure 16. Battelle and WSU aircraft flight paths during afternoon hours on
August 10, 1975, with ozone concentrations (ppb) marked at specific
points along the route.
45
-------
Along the Connecticut coast it was possible on a few occasions to observe
a potential recirculation cell in the sea and land breeze pattern. July 27
was such a day at Groton. Table 11 shows surface measurements made on this day
at Groton, Connecticut. Examination of the wind data indicates that the sea
breeze began about 1000 and persisted until about 2100. This is substantiated
by the slow temperature rise and the two degree increase in dew point between
0900 and 1000 as the more moist marine air moved onshore. This Groton sea
breeze cycle was especially notable because, in the afternoon, the Groton pibal
showed a flow reversal or recirculation in the winds aloft. The pibal data re-
corded at 1510 (Table 12) showed south winds through the lowest 1200 ft. and
then a backing of the wind to a northeast direction at 1850 ft. The northeast
winds persisted to the top of the mixing layer, about 3400 ft. This pattern is
believed to show a complete vertical sea breeze cycle where the onshore or
southerly movement of air in the lower layers is compensated for by offshore or
northerly winds above the surface layer.
As indicated earlier, a sea breeze recirculation cell provides a mecha-
nism whereby a given air parcel could be carried across the urban area twice
and thus produce an accentuated pollutant pattern. On July 27 at the WSU
Groton site (Table 11) 0- concentrations gradually increased during the morning
to peak values of 71 and 73 ppb at 1300 and 1400. After 1400, 03 levels
dropped but did not go below 60 ppb until 2200. Halocarbon measurements
(Fluorocarbon-11) showed that general pollutant levels on the 27th in the after-
noon were relatively low , and thus the afternoon 0- concentrations of over 60
ppb were accompanied by relatively clean air. The 03 pattern along the Con-
necticut coast west of Groton (Figure 18) varied some in the value of the mid-
day 03 maximum compared to Groton, but the pattern observed at Groton seems
typical of much of the Connecticut coast. The major differences occurred in
the extreme west, bordering New York City, where the urban plume effect could
be seen.
This episode seems to show that when conditions at Groton are such that a
strong recirculation sea breeze cycle can develop, the accompanying overall
pollutant pattern is characterized by only low to moderate levels of 03 and
other pollutants. Although a single example is obviously insufficient to prove
this correlation, basic features of the sea breeze pattern would favor such a
conclusion. First, along the Connecticut coast a well developed
46
-------
TABLE 11. SURFACE MEASUREMENTS AT GROTON, CONNECTICUT, ON JULY 27, 1975
Time
(hrs)
0100
0200
0300
0400
0500
0600
0700
0800
0900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
03
(ppb)
<5
<5
<5
<5
<5
<5
10
19
27
43
60
69
71
73
64
64
67
65
63
62
60
54
53
54
NO
(ppb)
26
14
8
8
6
8
12
10
9
8
7
7
6
7
6
6
6
7
5
6
5
6
5
5
NO?
42
36
30
28
18
18
14
8
-8
8
8
11
5
5
5
3
3
4
3
3
2
1
2
3
NMTHC
(ppm)
.3
<. 1
.2
.2
.2
.2
.2
.2
<.l
<.l
<.l
<. 1
<. 1
<.l
<.l
<.l
<.l
<. 1
<.l
<.l
<. 1
<. 1
<. 1
<.l
CO
(ppm)
1.3
1.1
.9
.8
.7
.6
.6
.5
.5
.6
.8
.9
.6
.6
.5
.5
.6
.5
.5
.5
.5
.5
.4
.4
CH4
(ppm)
1.6
1.6
1.6
1.6
1.6
1.6
1.7
1.6
1.6
1.6
1.6
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
(ppt)
355
270
255
245
220
220
205
195
190
195
200
185
170
155
145
145
155
150
145
140
145
145
140
140
CC14
(PPt)
622
592
253
189
146
137
128
128
128
128
128
128
128
128
131
131
131
131
128
128
128
128
128
128
W/S
(mph)
3
2
2
2
3
3
4
4
3
3
4
4
4
6
6
5
7
7
6
3
4
7
8
5
W/D
(deg)
020
040
020
025
020
020
020
010
030
140
135
130
195
195
195
205
190
185
170
190
150
210
230
265
(d°e6g)
12
18
15
20
15
16
13
18
18
19
20
7
8
7
7
5
6
6
14
9
11
18
8
8
RAD
(mLy)
0
0
0
0
5
200
525
800
1050
1275
1400
1325
1440
1450
1350
1150
850
625
325
20
0
0
0
0
TEMP
60
58
56
55
55
57
65
70
75
75
76
79
79
79
79
77
76
75
73
68
64
65
66
66
DP
53
52
52
51
51
52
54
55
57
59
61
58
61
61
58
57
56
57
58
56
57
58
57
59
-------
TABLE 12. PIBAL DATA FROM GROTON, CONNECTICUT, AT 1510
ON JULY 27, 1975
Layer height mid-point
(ft).
177
531
863
1000
1188
1515
1840
2000
2317
2775
3000
3085
3382
3678
3975
4000
4408
4862
5000
5453
5749
6000
6044
6340
6635
6931
7000
Wind direction
(degrees)
185
190
198
192
183
109
052
047
037
004
018
024
065
127
171
172
198
171
166
168
163
177
179
184
316
224
218
Wind speed
(mph)
5
4
2
3
3
1
4
5
6
6
3
2
2
3
1
2
6
8
7
7
5
2
2
3
7
4
5
48
-------
vo
Figure 17. Calculated trajectory (Stanford Research Institute ) of air mass
arriving at Groton, Connecticut at 1300 on August 10, 1975.
-------
circulation pattern will have a deep mixing layer and thus would tend to lessen
the impact of pollutant sources. Second, the presence of a local recirculation
system could probably not be detected if regional advection were also taking
place, and thus the levels of pollutants present in the recirculation systems
are going to be dependent primarily on local, not advected sources. In the
Groton area and along much of the adjacent coast, local sources are not large.
ALBANY^
0 10 20 40 60
Figure 18. Surface ozone concentrations (ppb) in southern New
England at 1300 on July 27, 1975.
50
-------
REFERENCES
1. Environmental Protection Agency, "Studies of Oxidant Transport Beyond
Urban Areas--1975 New England Study," in press.
2. F. Bacon, "Historia naturalis and experimental is de ventis," Opera
omnia edita impensis J. B. Schonwetteri, Frankforti ad monum, (1665).
3. W. van Bemmelen, "Land un seebrise in Batavia," Beitrage zur Physik
der Freien Atmosphare, J_0, 169 (1922).
4. H. Koschmieder, "Danziger seewindstudien," Danziger Meteorologische
Institut Forschungsarbeiten, J0_, 1 (1949).
5. E. L. Fisher, "An Observational Study of the Sea Breeze," J. Meteor.
V7, 645 (1960).
6. J. A. Frizzola and E. L. Fisher, "A Series of Sea Breeze Observations in
the New York City Area," J. Appl. Meteor., 2_, 722 (1963).
7. J. K. Angel 1 and D. H. Pack, "A Study of the Sea Breeze at Atlantic City,
New Jersey, Using Tetroons as Lagrangian Tracers," Mon. Wea. Rev., 93,
475 (1965).
8. G. S. Raynor, J. V. Hayes, and E. C. Ogden, "Mesoscale Transport and
Dispersion of Airborne Pollens," 0. Appl. Meteor, 13^, 87 (1974).
9. J. G. Edinger, "Modification of the Marine Layer Over Coastal Southern
California," J. Appl. Meteor.. 2_, 706 (1963).
10. W. A. Lyons and L. E. Olsson, "Mesoscale Air Pollution Transport in the
Chicago Lake Breeze," J. Air Poll. Control Assoc.. 2£, 876 (1972).
11. W. A. Lyons and H. S. Cole, "Photochemical Oxidant Transport: Mesoscale
Lake Breeze and Synoptic-Scale Aspects," J. Appl. Meteor.. ]5^ 733 (1976),
12. W. A. Lyons, "Turbulent Diffusion and Pollutant Transport in Shoreline
Environments," in Lectures on Air Pollution and Environmental Impact
Analyses, D. A. Haugen, ed., American Meteorological Society, Boston,
MA (1975).
13. Environmental Protection Agency, "1972 National Emissions Report," EPA-
450/2-74-012 (1974).
14. Environmental Protection Agency, "Ozone in the Northeastern United
States," EPA-901/9-76-005, in press.
51
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/3-77-055
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
STUDIES OF OXIDANT TRANSPORT BEYOND URBAN AREAS
New England Sea'Breeze - 1975
5. REPORT DATE
June 1977
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
H. Westberg, E. Robinson, D. Elias, and K. Allwine
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Air Resources Section
Chemical Engineering Department
Washington State University
Pullman. Washington 99164
10. PROGRAM ELEMENT NO.
1AA603 AJ-05 (FY-77)
11. CONTRACT/GRANT NO.
68-02-2239
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Sciences Research Laboratory - RTF, NC
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park. NC 27711 '
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/09
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Relationships between ambient air quality and sea breeze conditions in
southern New England are examined. In the Boston area, sea breeze conditions
were observed on approximately 25% of the days of the study (July-August 1975).
The sea breeze effect can either moderate or enhance the pollution levels in
the Boston area. However, the most common course for the sea breeze is to have
a cleansing effect. Therefore, ozone levels are generally lower during sea
breeze conditions.
In the Groton area of Connecticut, a well-developed sea breeze effect was
observed almost daily. High ozone concentrations usually coincided with a sea
breeze effect. Measurements from aircraft over Long Island and the Atlantic
ocean show that air pollutants are advected into the Groton area by the sea
breeze. The pollutants over the ocean were part of the large urban plume
originating in the New York City-New Jersey area.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Air pollution
Ozone
Transport properties
Sea breezes
Field tests
Airplanes
New England
13B
07B
04B
14B
QIC
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
62
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
52
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