United States
Environmental Protection
Agency
Atmospheric Sciences
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S3-85/033 July 1985
x>EPA Project Summary
Transport of Pollutants in
Plumes and PEPES: A Study of
Transport of Pollutants in
Power Plant Plumes, Urban and
Industrial Plumes, and Persistent
Elevated Pollution Episodes
William M. Vaughan
Because of the increased concern for
the regional nature of secondary air pol-
lutants (e.g., sulfates, nitrates, ox\-
dants, and aerosols) the U.S. Environ-
mental Protection Agency (EPA)
sponsored a major field program in the
northeastern United States during the
summer of 1980. Two EPA field pro-
grams were actually carried out simul-
taneously. One, an outgrowth of prior
power plant plume studies, addressed
persistent elevated pollution episodes,
and the other continued the 1979 north-
east regional oxidant study in develop-
ing part of the data base for the re-
gional oxidant model. Field activities
were based in Columbus, OH.
Ten research aircraft and several mo-
bile and stationary surface monitoring
platforms from three EPA contractors,
seven Federal agencies, and four Uni-
versities participated in the intensive
measurement program between 16
July and 15 August 1980. Pollutants
measured included SO2, NO, NO?, 03,
sulfate, nitrate, and aerosols. This re-
port describes the contractors' activi-
ties. Their aircraft logged over 350 flight
hours in 100 missions ranging as far
east as Laconia, NH, as far south as
Montgomery, AL, as far west as
Texarkana, AR, and as far north as Sag-
inaw. Ml.
Descriptive analyses are summarized
for urban plume missions and regional
missions. The quality assurance pro-
gram is described, showing the efforts
made to develop a well coordinated
data base. Sources for reports and data
are provided. Many subsets of the data
base can be used in model develop-
ment of transport, transformation, and
removal processes.
This Project Summary was devel-
oped by EPA's Atmospheric Sciences
Research 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
Increasing concern for the regional
nature of formation and transport of
secondary pollutants (e.g., sulfates, ni-
trates, oxidants, and aerosols) has led
the EPA to conduct major field studies
since the mid 1970's. The project report,
here summarized, describes activities
during the summer of 1980 that ad-
dressed the occurrence of Persistent El-
evated Pollution Episodes (PEPES) and
continued the Northeast Regional Oxi-
dant Study (NEROS). These activities
are known as The 1980 PEPE-NEROS
study.
The PEPE-NEROS study involved two
field programs coordinated from head-
quarters in Columbus, OH. PEPE opera-
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tions involved regional-scale missions
to characterize air masses transporting
aged pollutant mixtures. NEROS opera-
tions involved regional characterization
missions to provide parameterizations
for the Regional Oxidant Model (ROM)
as well as urban plume missions to de-
scribe inputs to the ROM. Common
weather forecasting, communications,
and data processing supported both
studies. Platforms were deployed for
PEPE or NEROS missions, dependent
on forecast conditons.
The prime contractor for this study
was Environmental Measurements, Inc.
with strong sub-contract support from
AeroVironment, Inc., SRI International,
and Washington University Technology
Associates. The project report focuses
on the activities of this contractor team.
Field Study
Participants and Platforms
The organizations that participated in
the PEPE-NEROS study are shown in
Table 1. Table 2 shows the nature of
their participation and the principal in-
vestigators involved.
Operations
Depending on weather conditions,
platform status, and study objectives,
specific PEPE or NEROS missions were
planned and executed. These missions
involved various mixes of activities and
geographic coverage.
The NEROS missions for urban and
regional studies involved release of
clusters of small tetroons at various alti-
tudes (97 tetroons were released and
tracked by NCAA-Idaho Falls), and re-
lease of a large EPA tetroon to be
tracked by FAA centers. The position of
the large tetroon could be phoned to
field headquarters in Columbus from
the FAA centers. Once the transport was
marked be tetroons, the aircraft and sur-
face platforms were deployed to docu-
ment the air quality and mixing condi-
tions in the air mass. CHOPPER and the
NOAA turbulence aircraft were princi-
pally dedicated to urban plume surveys.
The EPA Lidar plane mostly carried out
plume-oriented studies, but occasion-
ally conducted regional studies outside
Ohio. Moving Lab conducted frequent
ground-level surveys near Columbus,
but was also deployed to West Virginia
and Kentucky for PEPE-oriented re-
gional surveys.
NEROS regional measurements were
made between about 70 and 85° W
longitude, and 38 and 45° N latitude to
characterize the northeastern grid used
in the ROM. SCOUT, CHEM-1, and
CHEM-2 made frequent flights across
various parts of this NEROS area. They
were usually vectored to the location of
the large EPA tetroon in order to mea-
sure the aging of the air mass in the
vicinity of this specific marker.
ELECTRA was deployed for its re-
gional surveys from Wallops Island, VA
in support of NEROS and PEPE regional
measurements. CHEM-3 provided cor-
relative in situ measurements at se-
lected locations beneath ELECTRA's
flight path as it had done earlier in the
program for LAS-Queenair flights.
PEPE regional surveys were less re-
stricted, involving flights into stagnant
air masses (two to five days old) or into
moving air masses characterized by re-
gional visibility degradation, as re-
ported by FAA and National Weather
Service wire services and as detected by
satellite imagery. These regional sur-
veys extended into New York and New
England during the first week of August
1980, following development of
wide-spread haziness in the area. In the
middle of the second week of August,
several flights into Tennessee, Ala-
bama, and Arkansas were carried out to
characterize a maritime tropical air
mass associated with an extension of
the Bermuda high that had been station-
nary over Georgia and Tennessee for
four days. Measurements were also
made as this aged air mass moved out
to the Atlantic.
Both internal and external quality as-
surance activities were carried out
throughout the field measurement pro-
gram. The contractor team referenced
its platform measurements to a master
calibrator separate from each contrac-
tor's internal quality assurance pro-
gram. The team addressed the altitude
and time response of various instru-
ments and developed a uniform ap-
proach to data processing. Aircraft fly-
bys were conducted to provide in situ
platform comparisons. In addition, EPA
provided an external audit of most of
the project platforms through the ser-
vices of Research Triangle Institute and
PEDCO.
Data Base
The Project Report gives a summary
description of the data base that was
created at the Special Studies Data Cen-
ter at Washington University. This data
base is also available at EPA's Meteorol-
ogy and Assessment Division. These
Table 1. Participants in the PEPE
NEROS Study
Agencies
U.S. Environmental Protection Agency
ESRL - Research Triangle Park
EMSL - Research Triangle Park
EMSL - Las Vegas
National Oceanic and Atmospheric Admin-
istration (NOAA)
Boulder Laboratories (BL)
Idaho National Engineering Laboratory
(INEL)
National Science Foundation
National Center for Atmospheric Re-
search (NCAR)
National Aeronautics and Space Adminis-
tration (NASA)
Langley Research Center (LRC)
Jet Propulsion Laboratory (JPL)
Wallops Island
Department of Energy
Argonne National Laboratory (ANL)
Federal Aviation Administration (FAA)
Tennessee Valley Authority (TVA)
Ohio Environmental Protection Agency
Contractors
Environmental Measurements, Inc. (EMI)
AeroVironment, Inc. (AV)
SRI International
Washington University Technology Associ-
ates (WUTA)
MESOMET, Inc.
Battelle Columbus Laboratories (BCD
Research Triangle Institute
PEDCO Environmental
Universities
Washington University
Harvey Mudd College
Ohio State University
Others, supported by the Agencies
International
Atmospheric Environment Service of
Canada
Millan M. Millan of Barringer Research
N.D. van Egmond, Rijks Instituut voor de
Voksgezondheid
Bertin & Cie
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Table 2. Platforms and Operations During PEPE-NEROS
Airborne Platforms Source
Principal Investigator
CHEM-1 (Chemistry Aircraft)
CHEM-2 (Chemistry Aircraft)
SCOUT (Chemistry Aircraft)
ELECTRA (Lidar Aircraft)
CHEM-3 (Chemistry Aircraft)
LASC Queenair
EPA Lidar
Turbulence Aircraft
Cloud Chemistry Aircraft
CHOPPER (Chemistry Aircraft)
Surface Platforms
Moving Laboratory
Doppler Sodar ^ and 2
Aerosol Laboratory
Lidar Van
Tethered Balloon
Benin Sodar
MARSd
Other Operations
EMI
AV
SRI
NASA/LRC-
Wallops Island
NASA/LRC
NASA/JPL
EMSL Las Vegas
NOAA/BL
NCAR
EPA-TVA-EMI
EMI
AV
U. of Minnesota
SRI
NASA/LRC
Benin & Cie
NASA/JPL
Willian Vaughan
Ivar Tombach
Bruce Cantrell
Ed Browell (UV-DIAL)a
Jeffrey Scroga (HSRL)b
Gerald Gregory
Mike Schumate
Jim McElroy
Brad Bean
Al Lazrus
Willian Vaughan
Gary Klauber
Michael Chan
Peter McMurry
Ed Uthe
Otto Youngbluth
Pierre Huguet
Bruce Gary
Small Tetroon Tracking
Large Tetroon Tracking
GC Laboratory
Photochemistry Precursors
/VOX Ozone Network
Dry Deposition Experiment
Sun Photometer Network
Data Center
Weather Center
NOAA/INEL
SRI
ESRL
Harvey Mudd
EMI-BCL
ANL
NASA/LRC-
U. of Miami
WUTA
SRI
Gene Start
Walt Dabberdt
William Lonneman
Gregory Kok
William Vaughan
Marvin Wesley
Joe Prospero
Noor Gillani
William Viezee
aUV-DIAL Ultraviolet Differential Absorption Lidar
bHSRL High Spectral Resolution Lidar
CLAS Laser Absorption Spectrometer
dMARS Microwave Atmospheric Remote Sensor
magnetic tape data are in standard for-
mat and are available by individual plat-
form or by day with all measurements
linked by time.
The magnetic tape data base has a
companion hard copy data base with
data volumes for contractor platforms
and for special study measurements.
An overview volume summarizes
meteorological conditions and mea-
surement activities for each day.
Observations
As noted above, both urban plume
and regional missions were carried out.
These collections of data were reviewed
and assigned a priority based on appar-
ent quantity and quality of data. De-
scriptive analyses were then prepared.
AeroVironment prepared a descrip-
tive analysis report for the urban plume
surveys on 30-31 July and on 4,12, and
113 August 1980. Because of budget con-
straints, these analyses were focussed
on the flights of CHEM-2. SRI Interna-
tional prepared regional descriptive
analyses for the regional missions on 1
August and on 7-11 August 1980.
Urban Plume Descriptive Anal-
ysis
The data from CHEM-2 were closely
reviewed for chemistry information,
and the data from Lidar Van, Sodar-1
and -2, NWS soundings from Dayton,
and from tetroon releases were used to
evaluate the meteorological data. Air
parcel trajectories were constructed for
the five urban plume days noted above.
The air quality parameters measured by
CHEM-2 were summarized for the times
when CHEM-2 was considered to be in
the urban plume from Columbus.
The vertical extent of the plume was
determined from aircraft soundings and
was used to select the altitude range of
winds for trajectory calculations. The
width of the urban plume was graphi-
cally presented to show plume maxi-
mum and average concentrations as
well as background values to either side
of the plume and upwind of Columbus.
Seven air quality parameters were tabu-
lated for each traverse of the plume.
Values for the plume were sometimes
difficult to determine because of small
gradients, and often required subjective
judgements. Ozone served as the best
indic&tor of the urban plume.
On several occasions, trajectory eval-
uation indicated that measurements
may have been made to the side of the
urban plume. Measurements within the
urban plume indicated that higher
ozone levels tend to occur in the lower
portion of the plume, and that the
plume width, defined by elevated ozone
values, does not vary greatly, averaging
20 to 30 km. Some transects at greater
distances showed apparently narrower
ozone plumes, probably because only
the core of the plume was distinguish-
able from background values. Data
from other platforms may improve the
overall plume resolution.
The Columbus plume was much
easier to detect and track with a flow of
clean continental air from the northwest
than with a southwesterly flow when
the plumes from Cincinnati and Dayton,
OH made up the background air mass.
Regional Descriptive Analysis
Separate meteorological descriptions
were prepared for the time periods ex-
amined by SRI International. An exten-
sive array of meteorological data was
evaluated for each period, including
probabilistic treatment of trajectories
that were transporting the air.
The general measurement activities
of the surface and airborne platforms
were summarized in graphic form.
Tables were prepared summarizing the
average, maximum, and minimum
values of up to six air quality parame-
ters (O3, NOX, S02, bscat, sulfate, and ni-
trate) along various segments of the tra-
verses.
The 1 August 1980 measurements,
primarily by CHEM-2, involved follow-
ing an air mass of low visibility that was
exiting the east coast. It did not linger
over the Ohio Valley long enough to be-
come a major PEPE over that region.
Sampling proceeded eastward from
cleaner air over Ohio into the dirtier
trailing edge of the air mass. Because
the flight was approximately parallel to
the transport wind, measurements in
the eastern portion of the flight were
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made in older air parcels that had been
over Ohio 6-12 hours earlier. Definite
trends of increasing ozone, sulfate, ni-
trate, and light scattering show the pen-
etration of aged air parcels. Ozone, in
units of ppb, increased from about 90 in
eastern Ohio to about 115 in eastern
Pennsylvania and New Jersey, light
scattering, in units of 10~4 nrr1, in-
creased from 1 to 5; 2;'s aerosol sulfate,
in units of n,g m~3, increased from 23 to
a peak of 50, then dropped to about 32;
and nitrate, in units of ppb, increased
from 3 to 8. Vertical profiles showed lit-
tle stratification within the mixed layer.
The return flight documented the
cleaner air to the west, but also showed
dirtier air toward the surface as the air
stabilized after sunset. Aerosol sulfate,
in units of (xg rrT3 dropped from about
35 in New Jersey to about 15 in central
Pennsylvania, but increased to about 31
below 900 m elevation in eastern Ohio.
Meteorological conditions of 7-11 Au-
gust led to a broad region over the
southeast of relatively stagnant air that
was strongly influenced by the diurnal
heating cycle, with daytime convection
distributing the low visibility air near the
surface into a deep layer. This mixing
prevented the buildup of aerosols in a
layer near the surface that would have
led to even lower visibilities. In addition,
thunderstorms and associated washout
led to a patchy pattern, in both the hori-
zontal and vertical, of low visibility and
increased pollutant levels.
The northern part of the stagnation
region was initially monitored on 7-8
August following a Regional Air Mass
Characterization scenario, with a shift to
regional PEPE missions as the stagnant
air mass developed. The PEPE missions
were conducted through 11 August,
when an approaching cold front termi-
nated the episode. During the episode,
three regions of low visibility and high
ozone were characterized by measure-
ments. NEROS platforms obtained mea-
surements in one of these areas, over
the Washington, D.C. to New York, NY
corridor. Contractor platforms charac-
terized areas over the southeast portion
of the Ohio River valley, and then over
northern Alabama. Ozone values in the
main PEPE area to the west of the Ap-
palachians were generally above 90 ppb
and reached 150 ppb in some areas.
Light scattering coefficients up to
5 x 10~4 m"1 were measured.
Recommendations
The extensive, relatively homoge-
neous, and accessible data base that
now exists as a result of the PEPE-
NEROS field program is primed for fur-
ther use. It is a valuable data base be-
cause great care was taken to integrate
it into a coherent whole, from design
concept through field implementation.
This data base is a singular collection of
atmospheric measurements that ad-
dress:
• Transformation processes associ-
ated with acid rain issues
• Transport processes associated
with regional oxidant and visibility
issues
• Mixing and removal mechanisms
• Aerosol growth by heterogeneous
and homogeneous mechanisms
• The interaction of forecasts and
realtime trajectories with field sam-
pling strategies
• Other topics to be defined as atmo-
spheric process investigators and
modelers become aware of this re-
source.
William M. Vaughan is with Environmental Measurements, Inc., University City,
MO 63124.
Francis Pooler, Jr., is the EPA Project Officer (see below).
The complete report, entitled "Transport of Pollutants in Plumes and PEPES: A
Study of Transport of Pollutants in Power Plant Plumes, Urban and Industrial
Plumes, and Persistent Elevated Pollution Episodes," (Order No. PB 85-191
666/AS; Cost: $10.00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Atmospheric Sciences Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S3-85/033
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