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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