Table of Contents - The Atmospheric Studies Group at TRC

Section 1: Introduction
1.
OVERVIEW
1.1 CALPUFF Version 6 Modeling System
Version 6 of the CALPUFF modeling system is a full update to Version 5 of the system that allows subhourly
temporal resolution of both source characteristics and input meteorological fields, and sub-hourly
temporal resolution of modeled output fields. It incorporates all of the modules and features of Version 5,
which is a Guideline Model (Federal Register, 2003) recognized for regulatory use by the U.S.
Environmental Protection Agency (EPA). When data and simulations are made with a 1-hour timestep,
Version 6 is equivalent to Version 5. However, with effectively unlimited temporal resolution it provides
greater flexibility in modeling situations with complex source distributions that evolve over short
timescales.
Such a complex source treatment was needed in 1999 when a project-specific version of the CALPUFF
dispersion model was developed with funding from the National Aeronautics and Space Administration
(NASA). It was designed to accept non-gridded meteorological data and source data at sub-hourly
intervals (at time-scales as short as seconds), and to report concentrations for user-specified averaging
times as short as several minutes. Identified as CALPUFF Version 6.0, it was based on the 1-hour
version of the model that was in use at the time, CALPUFF Version 5.0. This implementation was
designed specifically for applications involving the Space Shuttle. As a result, it did not fully address all
source types available in the modeling system or any postprocessor other than CALPOST, nor did it
include the meteorological model CALMET and its preprocessors.
Significant advances had been made to CALPUFF since 1999, so CALPUFF Version 6.0 did not include
the technical enhancements and other capabilities present in the current versions of CALPUFF in 2005
when the USDA Forest Service expressed interest in coupling the CALPUFF Modeling System to its
AGDISP aerial spray dispersion model to extend its modeling capability for assessing the fate of material
that drifts downwind of application areas. Therefore, the USDA Forest Service funded the preparation of
a new version of the system that can accept variability in the meteorological fields as well as source
characteristics at sub-hourly intervals. The sub-hour time-varying structures implemented in CALPUFF
Version 6.0 have been adapted to the current version of CALPUFF and its postprocessors, making this
feature available for all options, including the ability to treat sub-hourly meteorological inputs and to
modify the output data file structures for the concentration, wet deposition flux and dry deposition flux
files to accommodate sub-hourly output. This has produced CALPUFF Version 6.1, which will become
the platform for all future model development efforts. Postprocessors modified include APPEND,
CALSUM, CALPOST, and POSTUTIL.
Sub-hourly time-varying structures were also designed and implemented in CALMET Version 6.0 and
those preprocessors that are needed to prepare the input datasets required by CALMET. This includes the
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