United States
Environmental Protection
Agency
Environmental Sciences Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S3-83-110 Dec. 1983
&EPA Project Summary
Ozone Plumes from Small
Cities and Ozone in High
Pressure Weather Systems
Chester W. Spicer, Darrell W. Joseph, Philip R. Sticksel, George M. Sverdrup,
and Gerald F. Ward
'/i
The report describes the results from
a five-week study to investigate ozone
transport in urban plumes of small cities
and the behavior of ozone in a moving
high pressure system traversing the
eastern half of the United States. The
study was a collaborative effort involv-
ing research groups from Battelle-
Columbus, the EPA Environmental Sci-
ences Research Laboratories and Wash-
ington State University. The results
show that small cities do affect ambient
ozone levels and under photochemically
reactive conditions can produce measur-
able ozone in downwind plumes. Stud-
ies of a moving high pressure system
revealed a vertical multilayer structure
for ozone. The origin of some of these
layers appeared to be stratospheric air
injected into the troposphere during
cyclogenesis in northern Canada. The
upper layer of ozone, found between
10,000 and 15,000 feet MSL, was
observed to cover nearly the entire
eastern half of the United States.
This Project Summary was developed
by EPA's Environmental Sciences Re-
search Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
This report presents the results of a
field investigation of ozone (03) distribu-
tion and transport. The program focused
on the formation and transport of Oa in
urban plumes of large and small cities,
and the behavior of Oa in a high pressure
weather system traversing the eastern
half of the U.S. The program involved
detailed ground-level and aircraft moni-
toring studies, and the analysis and
interpretation of the resulting data. This
study builds upon earlier investigations of
03 transport in the Ohio Valley and New
England.
The issue of Oa/precursor transport
has caused much controversy, and this
program was directed at providing addi-
tional information on various aspects of
the controversy. Specifically, we have
investigated the contribution of smaller
cities to the downwind 03burden and the
long-range transport of 03 associated
with a high pressure system.
Objectives
The overall objective of the program
was to determine the propensity of air
masses to generate and transport Q3over
long distances. Specific goals of the
project were'
• To investigate the transport of O3 and
precursors from urban areas, and
especially to determine whether
smaller cities contribute measurably
to the downwind Oa burden.
• To study the behavior of 03 associated
with high pressure weather systems.
• To improve current understanding of
O3 variations with altitude, with an
emphasis on obtaining more data at
higher altitudes (up to 20,000 feet
mean sea level (MSL)).
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Project Description
Field experiments were conducted in
July and August, 1977 in the midwestern
U.S. Both ground-level and airborne
monitoring were conducted and measure-
ments were made from two ground sites
and two twin-engine research planes.
Ground-level measurements were taken
at a site near St. Louis and at the Civic
Memorial Airport in Bethalto, Illinois,
where aircraft operations were also
based. The location of the airport in
relation to St. Louis and other urban
areas is noted in Figure 1. The variables
monitored by aircraft include Oa, oxides of
nitrogen (N0«), nitric acid (HON02), nitrate
(N03~), fluorocarbon-11, C2 to Cio hydro-
carbons, temperature, and dew-point
temperature. Ground-level measure-
ments included Oa, nitric oxides, NO, NOX,
peroxyacetyl nitrate, PAN, HONOa, fluoro-
carbon-1 1, nonmethane hydrocarbons
(NMHC), methane (CH4), carbon monoxide
(CO), total suspended particulates (TSP),
N03~, sulfate (S04=), ammonium (NH4+),
carbon (C), hydrogen (H), nitrogen (N),
temperature, relative humidity, radiation
intensity, wind speed and wind direction.
The study was a collaborative effort
involving Battelle-Columbus Laboratories,
EPA-ESRL, who provided detailed hydro-
carbon analyses of aircraft samples, and
Washington State University (WSU), with
whom we coordinated many aircraft
operations.
Results
The field investigation of atmospheric
O3 distribution and transport focused on
the formation and transport of Oa in urban
plumes of large and small cities, and the
behavior of 03 in a high pressure weather
system traversing the eastern U.S. Both
ground-level and airborne monitoring
were employed, and a comparison of the
ozone monitors aboard the two aircraft
showed agreement within 2.5 percent.
The project report describes the experi-
mental aspects of the field program and
interpretation of the data as they relate to
the program objectives. A succinct sum-
mary of the study findings follows.
• The St. Louis urban area generates
an 03 plume with O3 concentrations
approaching 300 ppb under stagnated
conditions.
• Smaller cities (populations <
100,000) generate a measurable Oa
plume under photochemically reac-
tive conditions. The additional Oa in
the plumes is related to the cities'
precursor emissions An isopleth
* Peoria
•Canton
KeokukJ "Macomb fB/oommgton
•Kirksville
Hannibal
• Moberly
• Mexico
Boonville
' ^Columbia
• Fulton
v Jefferson
City
Springfield
Danville
• »
Champaign
Jacksonville
+ Decatur
Iton
Mattoon* 'Charleston
i Effingham
i Civic Memorial Airport
' Edwardsville
St. Louis O> -Collinsville
• Belleville tCentralia
E. St. Louis
»Mt. Vernon
Rolla
* Lebanon
Chester . w. Frankfort
Murphysboro • 'Herrin
*» . r . * . -
Evansville
/• L. . i m • * Harnsburg
Carbondale Marion "
f
'Plains
Cape
Girardeau
Sikeston •
•Poplar
Bluff
Figure 1. Location of mobile labs and Civic Memorial Airport in the St. Louis area.
diagramof the Oaplume from Spring-
field, Illinois on August 3, 1977 is
shown in Figure 2.
• During the study of 03and precursors
in a high pressure weather system,
Oa concentrations near the surface
increased steadily over the three
days that it took the high to cross the
eastern U.S. Figure 3 shows the area
covered by the High Pressure Weath-
er System Study, the aircraft flight
tracks, and mixing-layer Oa concen-
trations. During flights over rural
areas, Oa concentrations of 30 to 40
ppb were observed on the first day
over Wisconsin, 70 to 90 ppb on the
second day over Ohio, and > 100 ppb
on the third day over Pennsylvania.
• During the studies in a high pressure
weather system traversing the east-
ern U.S., several layers rich in Oa
were observed in vertical profiles.
The upper layer of Oa, which was
found between 10,000 and 15,000
feet MSL, was observed to cover
nearly the entire eastern half of the
U.S. (from Wisconsin to Virginia).
Such a pervasive tropospheric O
layer has not been reported previ
ously. The source of this O3 layer was
demonstrated to be the stratosphere
• Analysis of vertical profile result!
and rawindsonde data during the
high pressure system study suggest!
that the pervasive O3 layer observe<
over the eastern U.S. at 10,000 t<
15,000 feet MSL resulted from ar
injection of stratospheric air into the
troposphere during cyclogenesis ir
northern Canada several days before
our observations over the U.S. If this
is the case, then the persistence o
03 in this elevated layer must be a
least 3 to 4 days.
• The Oa was injected into the tropo
sphere along a stable frontal layer
The injection was limited in time sc
that the Oa remained as a finite layei
when it later appeared above the
surface high pressure area in the
Midwest. The Oa in the frontal layei
did not extend to the ground in the
Midwest and thus there was no rise
in Oa at the surface marking the
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Q Jacksonville
Wind Direction
VI Springfield
Alton
•QEdwardsville
£*Collinsville
E. St. Louis
^Belleville
Ettingham
Ozone Concentration, ppb
<50
50-59
60-69
>70
D Central/a
frontal passage. The frontal stable
layer was also the subsidence inver-
sion overlying the high pressure
area. On the backside of the high
pressure area, the stratospheric Oa
within this inversion layer could be
distinguished from the anthropogenic
03 which filled the layer from the
ground to the base of the inversion.
Observations made during the cross-.
country traverse of this July high
pressure area led to the conclusion
that layers of stratospheric 03 with
concentrations in excess of the sur-
face ambient standard can be found
in the troposphere above a high
pressure area, but that the 03 in
these layers has no direct effect on
the surface concentrations in the
Midwest during the summer.
Figure 2. Ozone isopleths downwind of Springfield, Illinois, on August 3, 1977.
/? * ~ Muskegon
[56 Milwaukee] a
o . , J 54 64 *
Spiral ..'
• Virginia
Figure 3. O3 concentrations (ppb) along the paths of the Washington State University and
Battelle 's Columbus Laboratories cross-country flights between July 22 and July 24.
(Sites of spiral soundings are shown.)
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Chester W. Spicer. Darrell W. Joseph, Philip R. Sticksel. George M. Sverdrup, and
Gerald F. Ward are with Battelle-Columbus Laboratories. Columbus, OH
43201.
William A. Lonneman is the EPA Project Officer (see below).
The complete report, entitled "Ozone Plumes from Small Cities and Ozone in High
Pressure Weather Systems," (Order No. PB84-120 807; Cost: $ 19.00. subject
to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, v'A 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Sciences Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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