Documentation of the Evaluation of CALPUFF and Other Long ...

2.0 OVERVIEW OF APPROACH
2.1 SUMMARY OF TRACER TEST FIELD EXPERIMENTS
LRT dispersion models are evaluated using four atmospheric tracer test field studies as follows:
1980 Great Plains: The 1980 Great Plains (GP80) field study released several tracers from
a release site near Norman, Oklahoma in July 1980 and measured the tracers at two arcs
to the northeast at distances of 100 and 600 km (Ferber et al., 1981).
1975 Savannah River Laboratory: The 1975 Savannah River Laboratory (SRL75) study
released tracers from the SRL in South Carolina and measured them at several receptors
approximately 100 km from the release point (DOE, 1978).
1983 Cross Appalachian Tracer Experiment: The 1983 Cross Appalachian Tracer
Experiment (CAPTEX) was a series of three‐hour tracer released from Dayton, OH and
Sudbury, Canada during September and October, 1983. Sampling was made in a series of
arcs approximately 100 km apart that spanned from 300 to 1,100 km from the Dayton, OH
release site (Ferber et al., 1986).
1994 European Tracer Experiment: The 1994 European Tracer Experiment (ETEX)
consisted of two tracer releases from northwest France in October and November 1994
that was measured at 168 monitoring sites in 17 countries (Von Dop et al., 1998).
2.2 SUMMARY OF LRT DISPERSION MODELS
Up to six LRT dispersion models were evaluated using the tracer test field study data:
CALPUFF 9 : The California Puff (CALPUFF Version 5.8; Scire et al, 2000b) model is a
Lagrangian Gaussian puff model that simulates a continuous plume using overlapping
circular puffs. Included with CALPUFF is the CALMET meteorological processor (Scire et
al., 2000a) that includes a diagnostic wind model (DWM). The EPA has developed a new
Mesoscale Model Interface (MMIF; Emery and Brashers, 2009; Brashers and Emery, 2011;
2012) tool that will “pass through” output from the MM5 or WRF prognostic
meteorological models without modifying or rediagnosing the meteorological variables, as
is done in CALMET. A major objective of this study was to compare the CALPUFF model
performance using CALMET and MMIF meteorological drivers.
SCIPUFF 10 : The Second‐order Closure Integrated PUFF (SCIPUFF Version 2.303; Sykes et
al., 1998) is a Lagrangian puff dispersion model using Gaussian puffs to represent an
arbitrary, three‐dimensional time‐dependent concentration field. The diffusion
parameterization is based on turbulence closure theory, which gives a prediction of the
dispersion rate in terms of the measurable turbulent velocity statistics of the wind field.
The SCIPUFF contains puff splitting when wind shear is encountered across a puff and puff
merging when two puffs occupy the same space.
HYSPLIT 11 : The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT Version
4.8; Draxler, 1997) is a complete system for computing simple air parcel trajectories to
complex dispersion and deposition simulations. The dispersion of a pollutant is calculated
by assuming either puff or particle or hybrid puff/particle dispersion. In the puff model,
9 http://www.src.com/calpuff/calpuff1.htm
10 http://www.sage‐mgt.net/services/modeling‐and‐simulation/scipuff‐dispersion‐model
11 http://www.arl.noaa.gov/HYSPLIT_info.php
5