oEPA
United States
Environmental Protection
Agency
Environmental Sciences Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S8-82-023 Nov. 1982
Project Summary
PAL-DS Model: The PAL Model
Including Deposition and
Sedimentation
User's Guide
K. Shankar Rao and H. F. Snodgrass
PAL is an acronym for an air quality
model which applies a Gaussian
plume diffusion algorithm to point,
area, and line sources. The model is
available from the U.S. Environmental
Protection Agency and can be used for
estimating hourly and short-term
average concentrations of non-
reactive pollutants at multiple
receptors from several sources of each
type. PAL is intended to assess the
impact on air quality, on scales of tens
of meters to several kilometers, of
portions of urban areas such as
shopping centers, large parking areas,
and airports. Level terrain is assumed,
and pollutant removal processes are
ignored.
This report is a User's Guide to the
PAL-DS model that utilizes Gaussian
plume-type diffusion-deposition
algorithms based on analytical
solutions of a gradient-transfer model.
The PAL-DS model can treat
deposition of both gaseous and
suspended paniculate pollutants in
the plume since gravitational settling
and dry deposition of the particles are
explicitly accounted for. The
analytical diffusion-deposition
expressions listed in this report are
easy to apply and, in the limit when
pollutant settling and deposition
velocities are zero, they reduce to the
usual Gaussian plume diffusion
algorithms in the PAL model.
This report outlines the modifica-
tions of the PAL computer program to
include deposition. The information is
oriented to the model user and the
programmer. This report is not a
complete User's Guide to the PAL-DS
model; it should be used as a
supplement to the original User's
Guide for PAL.
This Project Summary was devel-
oped by EPA's Environmental Sci-
ences 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).
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K. Shankar Rao and H. F. Snodgrass are with the National Oceanic and
Atmospheric Administration. Oak Ridge. TN 37830.
Jack H. Shreffler is the EPA Project Officer I see below).
The complete report, entitled "PAL-DS Model: The PAL Model Including
Deposition and Sedimentation—User's Guide," (Order No. PB 83-117 739;
Cost: $8.00, 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
U.S. GOVERNMENT PRINTING OFFICE: 1982 659-O17/O864
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
PS 0000329
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