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). ------- 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 ------- |