N-/EPA
United States
Environmental Protection
Agency
Environmental Sciences Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S7-82-047 Sept. 1982
Project Summary
Green River Air Quality Model
Development: Meteorological
Data—August 1980 Field
Study in the Piceance Creek
Basin Oil Shale Resources Area
C. D. Whiteman, N. S. Laulainen, G. A. Sehmel, and J. M. Thorp
Special meteorological and air quality
studies were conducted during August
1980 in the Piceance Creek Basin oil
shale resource area of northwestern
Colorado as part of the U.S. Environ-
mental Protection Agency (EPA)-
sponsored Green River Ambient
Model Assessment program. The
objective of the limited field study was
to collect initial data for developing,
calibrating, and validating a mesoscale
air quality model. The specific goals of
the study were to investigate the
growth and characteristics ofconvec-
tive boundary layers that form over
the area during the daytime; to
characterize background pollutant
levels, visibility, and atmospheric
structure over the area; and to investi-
gate, by means of tracer experiments,
the dispersion and dry deposition of
pollutants released in nocturnal valley
drainage flows.
A DC-3 aircraft was equipped with
air pollution and meteorological
instruments; air quality and visibility
data were collected during flights over
the test area. A balloon-borne upper
air sounding system was used to
monitor temporal changes in the
convective boundary layer structure.
Dual tracer experiments were con-
ducted on four occasions in the
shallow Corral Gulch near the federal
oil shale lease tract C-a using nonde-
positing SF6 gas and depositing
lithium-traced particles collected on
two to five sampling arcs during well-
defined drainage flow events. The
processed data, collected during the
two-week field study is summarized
and presented. Analysis and interpre-
tation of these data will be presented
in future reports as part of the Green
River Air Quality model development
program.
This Project Summary was developed
by EPA's Environmental Sciences
Research Laboratory. Research Triangle
Park. NC, to announce key findings of
the research project that is fully
documented in a separate report of
the same title (see Project Report
ordering information at back).
Introduction
A special meteorological and air
quality measurement study was con-
ducted in the complex terrain of the
Piceance Basin of northwestern Colo-
rado to aid in the design, calibration, and
validation of a mesoscale air quality
model that is being developed under the
U.S. Environmental Protection Agency
(EPA)-sponsored Green River Ambient
Model Assessment (GRAMA) program.
The GRAMA program's overall objective
is to develop dispersion models with
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demonstrated applicability for evaluating
air quality impact development of the
Green River Oil Shale deposits in
Wyoming, Utah, and Colorado. The
specific goals of the two-week field
study were:
• to investigate the growth and char-
acteristics of convective boundary
layers (CBLs) or mixing layers that
form over the oil shale region
during the daytime,
• to characterize background pollu-
tant levels, atmospheric visibility,
and atmospheric structure over
the region, and
• to investigate, by means of a dual
tracer experiment using a particu-
late and a gaseous tracer, the
dispersion and deposition of pollu-
tants released into well-developed,
nocturnal valley drainage flows.
It was clearly recognized that a single
two-week study would insufficiently
characterize the meteorological pheno-
mena investigated. It was expected,
however, that the initial experimental
design and results would lead to
improved designs and refined physical
hypotheses that could be tested further
in future experiments.
The purpose of this report is to
present the processed data obtained in
the field study in a basic form that will
be useful to other investigators. Also,
the study will facilitate a scientific
interchange of ideas that may lead to
progress in understanding the meteo-
rology and air quality of this complicated
terrain region. Data analysis will be
presented in future reports, as part of
the Green River Air Quality model
development program.
Field experiments were conducted
jointly with other investigators who
performed related work in the oil shale
region during the same experimental
period. By combining forces with other
investigators, it was possible to reduce
costs and, at the same time, obtain a
larger data set for later analysis and use
by all investigators. The field program
described in this report was conducted
cooperatively with investigators from
the University of California Los Alamos
National Laboratory, who, under U.S.
Department of Energy and EPA spon-
sorship, investigated the transport and
diffusion of SFe tracer material in the
nocturnal drainage flows of Corral
Gulch near the federal oil shale lease
Tract C-a. Their work included upper air
and tethered balloon profiles taken to
characterize atmospheric conditions
during the tracer experiments and the
operation of an acoustic sounder and
surface meteorological stations. The
meteorological and tracer data collected
in their investigations have been
published in a separate report prepared
by the researchers of the Los Alamos
National Laboratory.
The Piceance Creek Basin of north-
western Colorado is one of several
basins in Colorado, Utah, and Wyoming
that are part of the Green River Oil Shale
Formation. The Piceance Basin is a
shallow basin that is inclined toward
the north-northeast. The two major
drainages in the basin, Piceance Creek
and Yellow Creek, drain northward into
the westward-flowing White River, a
major tributary to the Green River and
ultimately the Colorado River. The
major topographical features of the
region include the Cathedral Bluffs, the
steep cliffs forming the western rim of
the basin; the Roan Plateau, the name
given to the flat-topped highlands on
the south edge of the basin; and the
Grand Hogback, a sharp ridge of
resistant rock running from north to
south forming the eastern boundary of
the basin.
The CBL experiments were designed
to allow frequent soundings through
the entire depth of the CBL so that its
height, temperature and wind structures
could be determined as a function of
time during the day. These data were
collected primarily by balloon-borne
sondes released from a point on the
ground within the Piceance Basin.
Soundings were released at approxi-
mately three-hour intervals from sunrise
until late afternoon. Release times were
coordinated, as much as possible, to
allow comparison of Piceance Basin
profiles with rawinsonde profiles over
Grand Junction and with aircraft
profiles over other parts of the Piceance
Basin. The upper air data were obtained
with a commercial balloon-borne sound-
ing system using expendable sondes
that were towed aloft by a 50-g helium-
filled balloon. The time-multiplexed
radio frequency data were received by a
ground receiving station and decoded
into time, pressure, temperature, and
wet-bulb temperature information.
Upper air winds were obtained for the
sounding ascents by merging the
desired height data with data obtained
with an optical theodolite. Further
characteristics of the CBL were deter-
mined from aircraft soundings made
with it, including observations of
temperature, wind, and pollutant profiles
with height, atmospheric aerosol char-
acteristics within the layer, and visibility
measurements. In connection with the
CBL observations, components of the
surface energy budget were measured
at a site representative of the valley floor
in general, having a sparse cover of
sagebrush, bare soil, and natural
grasses. At this site, solar and net
radiation instruments were mounted at
the 1 -m level on booms that extended
out 1 m from a guyed mast. Nearby,
temperature sensors were inserted into
undisturbed soil at depths of 2,5, and 20
cm in the walls of a 20-cm deep
excavated pit.
In addition to the supporting role
played by the DC-3 aircraft m the CBL
experiments, separate experiments
were designed to use the aircraft as a
platform from which to measure back-
ground pollutant concentrations in the
oil shale region and to better define
horizontal variations in atmospheric
structure over the region during both
daytime and nighttime flights. Measure-
ments taken from the DC-3 aircraft
included ozone and sulfur dioxide
concentrations, aerosol concentrations,
and light-scattering coefficients, as
well as aerosol size distributions and
elemental compositions. Vertical profiles
were made over the oil shale region at
altitudes generally between 2300- and
4300-m MSL
The tracer experiments were designed
to answer basic scientific questions
about the transport, diffusion, and
deposition of pollutants introduced into
a valley drainage flow. In these experi-
ments two types of tracer materials were
utilized. The first type was a gaseous
SF6 tracer released by researchers from
Los Alamos National Laboratory. The
second type, a lithium-traced aerosol,
was released by researchers from
Battelle, Pacific Northwest Laboratory
so that comparisons could be made
between gas and aerosol tracer concen-
trations to determine how diffusion and
deposition will affect pollutant concen-
trations downwind of the pollutant
sources. These experiments were
conducted during the nighttime when
the valley drainage flow had become
well established and had attained a
near-steady state. Tracers were released
for 1 h so that transport velocities
within the drainage flow would allow
tracer to be carried through the length
of the sampling station grid. Sampling
stations were located along multiple
lines perpendicular to the valley axis at
various downwind distances from the
source. The lines extended across the
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valley floor and up the valley sidewalls.
Using this grid and the two tracer
materials, the experiments determined
transport, diffusion, and aerosol deposi-
tion as a function of downwind distance
from the tracer source.
Airborne tracer concentrations down-
wind of the release point were measured
using one of three methods:
• Samples of SFe and lithium-traced
particles were collected and de-
tected in real time at the Tract C-a
Visitor's Center and at Meteoro-
logical Site 3 using commercial
instrumentation.
• Samples of SF6 were collected
using bag samplers distributed
along four radio-controlled sam-
pling lines oriented perpendicular
to the valley axis at distances of 1.6,
2.5, 4.6, and 5.6 km down valley
from the release point. SFe con-
centrations were determined from
these samples after collection.
• Samples of SF6 were collected in
syringes at various points along a
road that runs perpendicular to the
valley axis approximately 6.8-km
below the release point. Concen-
trations were determined from
these samples after collection.
Conclusions and
Recommendations
The field experiments are described,
the design and characteristics of the
data collection systems are specified,
and the data are summarized in the
form of figures and tables. The experi-
ments, rather than focusing on the
collection of large quantities of general
background meteorological and air
quality data, were directed at investi-
gating specific meteorological pheno-
mena, including the evolution and
characteristics of atmospheric mixing
layers and the dispersion capabilities of
nocturnal valley drainage flows. The
reported data will constitute important
input into development of a mathe-
matical model of pollutant transport and
diffusion in the oil shale region now
being developed at Pacific Northwest
Laboratories. It is important to note,
however, that further investigations of
the meteorology and air quality of this
sparse and very complicated topograph-
ic region are essential. It is recommended
that a much more comprehensive set of
experiments be initiated in the near
future to obtain a better understanding
of regional environmental effects of the
development of oil shale resources in
the Piceance Basin. Modeling work will
benefit from the phenomenological
approach advocated here, but other
phenomena (e.g., the buildup and
breakdown of temperature inversions,
the evolution of local wind systems, the
coupling and decoupling of synoptic and
valley flows, etc.) must be observed and
the scope of the observational work in
both time and space be expanded.
C. D. Whiteman, N. S. Laulainen. G. A. Sehmel, andj. M. Thorp are with Battelle,
Pacific Northwest Laboratory, Rich/and, WA 99532.
Alan H. Huber is the EPA Project Officer (see below).
The complete report, entitled "Green River Air Quality Model Development:
Meteorological Data—August 1980 Field Study in the Piceance Creek Basin
Oil Shale Resources Area." (Order No. PB 82-258 609; Cost: $ 15.00. 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:
Environmental Sciences Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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