United States
Environmental Protection
Agency
Atmospheric Sciences
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S8-86/024 Jan. 1987
&EPA Project Summary
INPUFF 2.0—A Multiple
Source Gaussian Puff
Dispersion Algorithm User's
Guide
William B. Petersen and Leonidas G. Lavdas
INPUFF is a Gaussian Integrated
PUFF model. The Gaussian puff diffu-
sion equation is used to compute the
contribution to the concentration at
each receptor from each puff every time
step. Computations in INPUFF can be
made for a single or multiple point
sources at up to 100 receptor locations.
In practice, however, the number of re-
ceptors should be kept to a minimum.
In the default mode, the model as-
sumes a homogeneous wind field.
However, the user has the option of
specifying the wind field for each mete-
orological period at up to 100 user-
defined grid locations. Three dispersion
algorithms are utilized within INPUFF
for dispersion downwind of the source.
Optionally the user can incorporate his
own subroutines for dispersion and
plume rise. Removal is incorporated
through deposition and gravitational
settling algorithms. A software plotting
package is provided to display concen-
tration versus time for a given receptor
and the puff trajectories after each sim-
ulation time.
This Project Summary was devel-
oped by EPA's Atmospheric Sciences
Research Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
INPUFF is a Gaussian Integrated PUFF
model with a wide range of applica-
tions. The implied modeling scale is
from tens of meters to tens of kilome-
ters. The model is capable of addressing
the accidental release of a substance
over several minutes, or of modeling
the more typical continuous plume
from a stack. Several requests to the
Meteorology Division for assistance in
modeling the air quality downwind of
incineration ships prompted the devel-
opment of an integrated puff model. IN-
PUFF is, therefore, capable of simulat-
ing moving point sources as well as
stationary sources.
Computations in INPUFF can be made
for multiple point sources at up to 100
receptor locations. In practice, however,
the number of receptor locations should
be kept to a minimum to avoid exces-
sive run time. INPUFF is primarily de-
signed to a model a single event during
which one meteorological transition pe-
riod may occur, such as, going from af-
ternoon to evening conditions. Up to
144 separate meteorological periods of
the same length may be used to charac-
terize the meteorology during the
event; this provides a time resolution
that ranges from minutes to an hour.
The user has the option of specifying
the wind field for each meteorological
period at up to 100 grid locations or al-
lowing the model to default to a homo-
geneous wind field.
Three dispersion algorithms are used
within INPUFF for dispersion downwind
of the source. The user may select the
Pasquill-Gifford (P-G) scheme or the on-
site scheme for short travel time disper-
sion. The on-site scheme, so named be-
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cause it requires specification of the
variances of the vertical and lateral wind
direction. The long travel time scheme
is the third dispersion algorithm in
which the growth of the puff becomes
proportional to the square root of time.
Optionally, the user can incorporate his
own subroutine for estimating atmos-
pheric dispersion.
INPUFF utilizes the deposition al-
gorithms based on analytical solutions
of a gradient-transfer model. In the limit
when pollutant settling and dry deposi-
tion velocities are zero, these expres-
sions reduce to the Gaussian diffusion
algorithms.
A software plotting package has also
been provided to display concentra-
tions versus time for a given receptor
and the puff trajectories after each sim-
ulation period.
Features and Limitations
Several requests to the Environmen-
tal Operations Branch for assistance in
modeling the air quality downwind of
incineration ships stimulated the devel-
opment of INPUFF, a model capable of
simulating a moving point source in a
spatially variable wind field. The model
also possesses the following features
which increase its flexibility and range
of application:
• Optional stack-tip downwash,
• Wind speed extrapolated to release
height,
• Temporally variable source charac-
teristics,
• Temporally and spatially variable
wind field,
• Up to 100 receptors,
• Some consideration of terrain ef-
fects through the wind field,
• Optional buoyancy induced disper-
sion,
• Optional deposition and settling,
• Optional user-supplied dispersion
parameters,
• Optional user-supplied plume rise,
and
• Optional graphics display.
Although INPUFF has several advan-
tages over its continuous plume coun-
terparts, it still retains several limita-
tions, including:
• Wind direction constant with
height,
• No ponsideration of chemical reac-
tions,
• No explicit treatment of complex
terrain,
• No consideration of building wake
or cavity effects.
Data Requirements
INPUFF requires data on user options,
grid dimensions, sources, meteorology,
receptors, and plotter control. The user
must indicate whether the following op-
tions are to be employed:
• Stack-tip downwash,
• Source update,
• User-supplied wind field,
• Intermediate concentration output,
• Puff information output,
• Buoyancy induced dispersion,
• User-supplied dispersion algo-
rithm, and
• User-supplied plume rise algo-
rithm.
The dimension of the modeling grid
must be specified. If the user-supplied
wind field option is implemented, then
the dimension of the meteorological
grid along wth the size of each grid
rectangle must also be indicated. It is
recommended that both grids be given
a common origin. If a puff travels out-
side the modeling region, it is deleted
from futher consideration. If it travels
outside the meteorological grid, but is
still within the modeling region, the
wind at the nearest grid point to the puff
is used to advect it further.
Information on the source includes
the following:
• Location (km),
• Emission rate (g/sec),
• Physical stack height (m),
• Stack gas temperature (K),
• Stack diameter (m),
• Stack gas velocity (m/sec),
• Stack gas volume flow (m3/sec),
• Initial dispersion parameters (m),
and
• Deposition and gravitational set-
tling velocities (cm/sec).
Also, the direction and speed of the
source, if it is moving, must be provided
as input.
The meteorological data needed for
the computations are as follows:
• Wind direction (deg),
• Wind speed (m/sec),
• Mixing height (m),
• Stability class (dimensionless),
• Standard deviation of elevation
angle (radians),
• Standard deviation of azimuth
angle (radians),
• Ambient air temperature (K), and
• Anemometer height (m).
The user has the option of updating the
meteorological information after each
meteorological time period. The loca-
tion and height of each receptor must
be indicated. If dispersion is character-
ized by the on-site scheme, then the
standard deviations of the azimuth and
elevation angles are required.
The following information is required
by the plot routines:
• Type of plot desired,
• Location of concentration versus
time plots, and
• Plotting grid.
The plot routines were developed on a
UNIVAC 1110 and use CALCOMP plot-
ting software.
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The EPA author, W. B. Peterson (also the EPA Project Officer, see below),
is with Atmospheric Sciences Research Laboratory, Research Triangle Park,
NC 27711; and L G. Lavdas is with USDA, U.S. Forest Service, Dry Branch,
GA 31020.
The complete report, entitled "INPUFF 2.0—A Multiple Source Gaussian Puff
Dispersion Algorithm: User's Guide," (Order No. PB 86-242 450/AS; Cost:
$18.95, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, V'A 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
3. OFFICIAL MAR.1
United States
Environmental Protection
Agency
Center tor hnvironmentai Kesearcn
Information
Cincinnati OH 45268
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