11,
United States
Environmental Protection
Agency
Atmospheric Sciences
Research Laboratory "x
Research Triangle Park NC 27711 '
Research and Development
EPA/600/S3-86/002 Mar. 1986
ve/EPA Project Summary
EPA Complex Terrain Model
Development: Description of a
Computer Data Base from Small
Hill Impaction Study No. 2,
Hogback Ridge, New Mexico
Lawrence E. Truppi
As part of the U.S. Environmental
Protection Agency's effort to develop
and demonstrate a reliable model of at-
mospheric dispersion for pollutant
emissions in irregular mountainous
terrain, the Complex Terrain Model
Development Program was initiated in
1980 with Environmental Research
and Technology, Inc., as the prime
contractor. In October 1982, a field
experiment. Small Hill Impaction Study
#2 (SHIS #2), was conducted along an
approximately 1.5-km section of the
Hogback Ridge near Farmington, New
Mexico, to extend the modeling data
base to include a study of flow and
dispersion around a two-dimensional
ridge. Eleven quantitative 8-h tracer
experiments were performed, at night
or early in the morning. Meteorological
data were recorded at two instru-
mented towers upwind of the ridge and
at two towers on the slope. Data con-
sisted of direct and derived measure-
ments of wind, turbulence, and tem-
perature averaged at 5-min and 1-h
intervals. Hourly profiles of wind, tem-
perature, pressure, and humidity were
recorded at one tethersonde upwind of
the ridge while wind and temperature
were recorded at 13-s intervals at
another tethersonde held level at the
point of tracer release. Three sets of
optical crosswind anemometers mea-
sured path-averaged wind speed across
the base, slope, and crest of the ridge.
Thirty-minute averages of solar and net
radiation were also recorded.
Tracer gas concentrations, SF6 and
Freon 13B1, were detected by a net-
work of 110 samplers located on the
slopes of the ridge. The system used to
collect the data and the operational
procedures used to run the system are
presented along with values of 1-h
normalized tracer concentrations. Con-
centrations were also recorded from
collocated samplers to establish com-
parative data for quality control,
samplers operating at 10-min intervals
and samplers operating at different
heights on two towers on the slope of
the ridge. Tables of tracer gas release
data, emission rates, and heights and
locations of release have been included
to assist any modeling effort. All mete-
orological and tracer gas concentration
data have been edited and recorded on
magnetic tape and are now available
upon request from the National Com-
puter Center, Research Triangle Park,
North Carolina, either as hard copies or
by interactive computer access.
This Project Summary was devel-
oped by EPA's Atmospheric Sciences
Research Laboratory. Research Tri-
angle Park. NC, to announce key find-
ings of the research project that is fully
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documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
The extensive development of energy
resources, especially in the mountain-
ous terrain of the western United States,
has generated concern about the result-
ing impact on air quality (as well as on
water and land quality). Even in relatively
simple situations, it has been difficult
to produce reliable calculations of at-
mospheric transport and diffusion. For
complex terrain, mathematical model-
ing is confounded because physical
processes are more complicated and
meteorological measurements are less
"representative" than for level terrain
settings. Responding to this funda-
mental problem, the U.S. EPA has initi-
ated the Complex Terrain Model De-
velopment (CTMD) Program, a major
effort to develop and demonstrate reli-
able models of atmospheric dispersion
for emissions in mountainous terrain.
An early step in the development of
this program was the convening of a
workshop on problems in modeling
atmospheric dispersion over complex
terrain. Following recommendations of
the workshop report, EPA's, CTMD Pro-
gram involves a coordinated effort in
mathematical model development, field
experimentation, and scaled physical
modeling. The program's basic objective
is to produce practical models with
demonstrated reliability. Initially, the
CTMD Program focused on the problem
of stable plume impaction/interaction
with elevated terrain. This phenomenon
was singled out because of the likelihood
of relatively high concentrations on the
slopes of hills and ridges and because
models that are in use have been chal-
lenged extensively. The approach has
been to study stable plume interactions
in relatively simple terrain settings first,
and then to study them in more complex
situations.
EPA's prime contractor for the CTMD
Program is Environmental Research and
Technology, Inc. (ERT). Significant con-
tributions are also being provided by
EPA's Fluid Modeling Facility (FMF), the
National Oceanographic and Atmos-
pheric Administration's (NOAA) Wave
Propogation Laboratory (WPL) through
their sophisticated measurement capa-
bilities, and NOAA's Air Resources
Laboratory Field Research Division,
which conducted the flow visualization
and tracer experiments and operated the
real-time data acquisition and analysis
system. The first phase, a comprehensive
tracer field study designated as Small Hill
Impaction Study No. 1 (SHIS #1) was
carried out on Cinder Cone Butte (CCB), a
roughly axisymmetric, isolated 100-m
hill near Boise, Idaho, during the autumn
of 1980. The SHIS #1 tracer gas source
data (emission rates, locations, and
heights of SF6, Freon 13B1 (CF3BR), and
oil-fog releases), concentration data, and
meteorological data from six towers, a
tethersonde, and free balloons were sub-
sequently delivered to EPA to form an
accessible computer data base.
In October 1982, the second phase
of the CTMD program. Small Hill Impac-
tion Study #2 (SHIS #2), was conducted
along Hogback Ridge in New Mexico.
This summary describes the data
collected during the second phase of
CTMD, SHIS #2, a field study conducted
along an approximately 1.5-km section
of the Hogback Ridge near Farmington,
New Mexico, to extend the modeling
data base to include a study of flow and
dispersion around a two-dimensional
ridge. It is expected that these new data
will provide a good basis for testing
and extending the impingement and
neutral models and the dividing stream-
line concept for two-dimensional ridges.
This summary describes the setting
of Hogback Ridge, the experimental ap-
proach, and the following types of data
archived on magnetic tape in five sets of
data files:
• Tower meteorological data,— re-
corded at 5-min and 1-h averages
of wind, temperature, and turbu-
lence scales (sigma-u,-v,-w):
150-m tower instrumented at 10
levels, a 30-m tower instrumented
at 5 levels, a 10-m tower instru-
mented at 3 levels, and a 60-m
tower instrumented at 2 levels.
• Tracer gas concentrations — re-
corded at 10 min and 1 h averages
of SF6and Freon 13B1 (CF3BR).
• Wind speed — recorded by three
optical crosswind anemometers
10-min averages.
• Height, wind temperature, relative
humidity and mixing ratio — re-
corded at two tethersonde sites,
one operated at source elevation to
document meteorological condi-
tions in vertical soundings at the
source of tracer release and one
operated upwind and near the base
of the ridge to measure vertical
profiles.
• Surface meteorological data from
ten stations operated by Public
Service Company of New Mexico —
recorded at 20-min averages of
wind speed and direction at all sites
and temperature, solar, and net
radiation at one site on the crest of
Hogback Ridge.
Tables of tracer gas release data,
emission rates, and locations and heights
of release are included. Although lidar
measurements and extensive photo-
graphs were made of the oil-fog plumes,
those data are not available for this
publication.
Results
Meteorological Tower Data
Four sets of meteorological tower data
are stored on magnetic tape files. The
first set of files, numbers 1 to 176, re-
cords data from levels on the 150-m
tower A, which was located east of Hog-
back Ridge to determine an upwind
profile of wind, temperature, and turbu-
lence. Data are presented as 5-min
averages.
The second set of files, numbers 177
to 352, contains data recorded at tower B,
a 30-m tower located on the slope of
Hogback Ridge; tower C, a 10-m tower on
the crest of Hogback Ridge; and tower P,
a 60-m tower operated by Public Service
Company of New Mexico and located 3.6
km east of tower A. Data are values
of wind, temperature, and turbulence
averaged at 5-min intervals.
The third set of files, numbers 353 to
363, contains 1 -h averages of data from
tower A. The data are the same as those
used in the first set of files.
The fourth set of files, numbers 364
to 374, are 1-h averages of data from
towers B, C, and P. The data are the
same as those used in the second set of
files.
Tracer Gas Concentration Data
Tracer gas concentrations recorded by
a network of 110 samplers on the slopes
of Hogback Ridge as 1 h or 10-min
values are recorded on two sets of tape
files, numbers 375 to 385 and 386 to
396.
The first set lists concentrations of
SFe; the second set lists concentrations
of Freon 13B1 (CF3BR). Concentrations
are presented both as normalized values,
CHI/Q, and as measured values, Chi.
Each tape record also presents the tracer
emission rate, Q.
Optical Anemometer Data
Three files, numbers 397 to 399, con-
tain path-averaged crosswind anemome-
ter data. The first file lists data from path-
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A, aligned across the base of Hogback
Ridge; the second file lists data from path
B, aligned the east slope of Hogback
Ridge and the third file lists data from
path C, aligned on the crest.
Tethersonde Data
The first set of files, numbers 400 to
412, contains tethersonde data from
profile soundings taken upwind of
Hogback Ridge. Data are values of height,
wind, temperature, relative humidity,
and mixing ratio.
The second set of files, numbers 413
to 423, contains tethersonde data from
instruments held stationary at the point
of tracer release. Data are values of wind
and temperature.
Public Service Company of
New Mexico Data
Public Service Company of New
Mexico maintains a network of mete-
orological stations around Hogback
Ridge, and these data were made avail-
able by the company for inclusion in this
data base as half-hour averages for the
month of October 1982 from all ten sta-
tions in the network. Data are presented
on four files, numbers 424 to 427, and
consists of values of wind, temperature,
and solar and net radiation at one station.
Conclusion
All data files are stored at the National
Computer Center, Environmental Re-
search Center, Research Triangle Park,
North Carolina, on the Sperry UNIVAC
1100/83 system's magnetic tape: nine
track, odd parity, ASCII-quarter word
mode, density 6250 BPI, tape number
004972. UNIVAC users or users of inter-
active computers may assign the tape
with UNIVAC Executive Control Lan-
guage statement @ASG,T HBR,U9S
//////Q,004972. Copies of the tape
can be produced and translated into
formats acceptable to any computer
using nine-track tape drives.
The EPA author, Lawrence E. Truppi. is on assignment from the National Oceanic
and A tmospheric A dministration. Department of Commerce, to the A tmospheric
Sciences Research Laboratory. Research Triangle Park. NC 27711.
Peter L. Finkelstein is the EPA Project Officer (see below).
The complete report, entitled "EPA Complex Terrain Model Development:
Description of a Computer Data Base from Small Hill Impact/on Study No. 2,
Hogback Ridge. New Mexico," (Order No. PB 86-144 870/AS; Cost: $11.95.
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
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S3-86/002
0000329 PS
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