United States
Environmental Protection
Agency
Atmospheric Sciences
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S8-87/046  Dec. 1987
 Project Summary
User's  Guide for  RAM-
Second  Edition

Joseph A. Catalano, D. Bruce Turner, and Joan H. Novak
   RAM is an air quality model based
 on the Gaussian-plume simplification
 of the  diffusion  equation which
 assumes time  independence in the
 input meteorology and concentration.
 The model is primarily used to deter-
 mine short-term (one hour to one day)
 concentrations  from  point and  area
 sources. A  maximum of 250  point
 sources and 100 area sources can be
 considereed to yield pollutant concen-
 trations at a maximum of 180 recep-
 tors. The simulation is  done using
 hourly meteorological data for periods
 ranging from one hour to one year. A
 default option is available in the model
 for regulatory applications. Use of this
 option automatically sets  certain
 parameters to preassigned values for
 consistency with the ' 'Guideline on Air
 Quality Models  (Revised)" (EPA,
 1986).
   This Project  Summary was devel-
 oped by EPA's Atmospheric Sciences
 Research Laboratory. Research Trian-
 gle 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).

   The  RAM  algorithm is  a Gaussian-
 plume  dispersion model that calculates
 short-term pollutant concentrations from
 multiple point and/or area sources at a
 user-specified receptor grid in  level or
 gently  rolling terrain.  Pollutants consi-
 dered are relatively non-reactive, such as
 sulfur  dioxide and  suspended  particu-
 lates. Both urban and rural situations can
 be simulated. In the rural mode, the
 model  uses the Pasquill-Gifford disper-
 sion parameters; in the  urban mode.
those proposed by Briggs based on the
work of Pooler-McElroy are used. Plume
rise is calculated following the methods
of Briggs and both buoyancy  rise  and
momentum rise are included. For point
sources, concentrations are determined
using distance crosswind and distance
upwind from the receptor to each source.
For area sources, the narrow plume
simplification  of Gifford and Hanna is
used with the  modification that the area
sources are not at ground level, but have
an effective height.
  Inputs to the model are a set of options
selected by the user, source parameters,
meteorological data, and receptor infor-
mation.  Using the hourly meteorology,
concentrations are calculated for recep-
tor locations either specified by the user
or generated by the program. Emissions
and source parameters for point or area
sources are required inputs. The meteo-
rological data base,  and hence  the
simulation,  can vary from one hour to
one year. Concentrations for 5 averaging
periods can be computed. For long-term
runs such as  a year, a high-five tabu-
lation can be obtained  to determine the
highest and second highest concentra-
tions at each  receptor for each of  five
averaging  periods.  Receptors can  be
specified  by the  user  or they can  be
generated by  the program. If they  are
input by the user, receptor name as well
as coordinates may be provided on input.
  For model execution, the user specifies
parameters  and options needed for the
application. Requried  parameters  are
type  of pollutant,  number of  sources,
averaging  periods), power-law wind-
profile exponents, and whether the urban
or rural mode is to be used. Options are
included for the  treatment of stack-tip

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   downwash, gradual plume rise,  and
   buoyancy-induced dispersion. The user
   also specifies types of sources and those
   that are significant, receptor configura-
   tion, characteristics of emission sources,
   and meteorological inputs. Whether the
   run is part of a segmented run, outputs
   desired, and use of the default feature
   are also specified by the user. The default
   feature sets parameters and options for
   regulatory application;  final plume rise
   and momentum plume rise are used as
   are buoyancy-induced dispersion  and
   stack-tip downwash. Calm wind  condi-
   tions are  treated following the "Calms
   Processor (CALMPRO) User's Guide."
     Both  point and  area sources are
   considered by  the model. Their particu-
   lars can be included in the run stream
   or they can be read from disk or tape
   files. Source coordinates and parameters
        must be given, as well as emisison rates.
        A total of 250 point sources and 100 area
        sources are permitted. Of these, up to
        25  point sources and 10  area sources
        can be labeled significant to obtain their
        contribution at a receptor separately.
          As with  the  data  on  emissions, the
        meteorology can be read as part of the
        input stream, from  a file  processed by
        the  program RAMMET, or from a file
        having the format of RAMMET. Surface
        parameters and mixing height must be
        present for each simulation  hour; the
        meteorological file is of a variable length
        from one hour to one year.
          Receptors can be specified by the user
        or they can be generated by the  model.
        If they are input by the user, receptor
        name  as  well  as coordinates may be
        provided. If generated by  the program,
        the user selects whether  a polar coor-
dinate grid of 180 receptors (36 radials
by 5 distances) or a honeycomb receptor
configuration  is  desired. Also, when
significant sources are  specified,  the
model selects two receptors downwind
of each source where maxima are likely
to occur. A total  of 180 receptors  are
permitted.
  On output, the model produces printed
and disk or tape files. The printed output
lists the options and source information
including a ranking according to source
height; those selected by the  user as
significant are properly identified. Recep-
tors are next listed with their appropriate
coordinates.  This is  followed  by  the
meteorological parameters as input by
the user.  Model-calculated  concentra-
tions are tabulated by receptor.  Various
other output files can be obtained.
      Joseph Catalano is with Aerocomp, Inc.. Costa Mesa, CA 92626; the EPA authors
        Bruce Turner (also the EPA Project Officer,  see  below) and Joan Novak
        are with the Atmospheric Sciences Research Laboratory, Research  Triangle
        Park, NC 27711.
      The complete report, entitled "User's Guide for RAM—Second Edition," fOrder
        No. PB 88-113 261/AS; Cost: $25.95. 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. NC27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S8-87/046

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