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

other major CALPUFF options for 600 km BASE case scenario matched the original 1998 EPA
analysis. There were no significant differences between the CALPUFF parameters 100 km BASE
case scenarios for the 1998 (CALPUFF Version 4.0) and the current evaluation (CALPUFF
Version 5.8).
Table 3‐5. CALPUFF Parameters July 8, 1980 GP80 experiment, 1998 and Current 600km
analysis.
600KM
CALPUFF
1998 EPA BASE
Option Description
Setup Setup
MSHEAR
Vertical wind shear is modeled above stack
top? (0 = No; 1 = Yes)
0 1
MPARTL
Partial plume penetration of elevated
inversion? (0 = No; 1 = Yes)
0 1
WSCALM
Minimum wind speed (m/s) for non‐calm
conditions
1.0 0.5
XMAXZI Maximum mixing height (meters) 3300 3000
XMINZI Minimum mixing height (meters) 20 0
XMXLEN Maximum length of slug (in grid cells) 0.1 1
XSAMLEN
Maximum travel distance of puff/slug (in grid
cells) during one sampling step
0.1 1
MXNEW
Maximum number of slugs/puffs released
during one time step
199 99
SL2PF
Slug‐to‐puff transition criterion factor
(= sigma‐y/slug length)
5.0 10.0
3.2.2 GP80 CALPUFF/CALMET Sensitivity Tests
Table 3‐6 and 3‐7 describe the CALMET/CALPUFF sensitivity tests performed for the modeling
of the 100 km and 600 km arcs of receptors. The BASEA simulations use the same configuration
as used in the 1998 EPA CALPUFF evaluation report for the 100 km arc simulations, only
updated from CALPUFF Version 4.0 to CALPUFF Version 5.8. For the 600 km arc simulations,
the BASEA used the same configuration as the 1998 EPA study only the near‐field slug option
was not used. The CALMET and CALPUFF parameters of the BASE case simulations were
discussed earlier in this section.
The sensitivity simulations are designed to examine the sensitivity of the CALPUFF model
performance to choice of grid resolution in the CALMET meteorological model simulation (10
and 4 km for the 100 km arc of receptors and 20 and 4 km for the 600 km arc of receptors), the
use of and resolution of the MM5 output data used as input to CALMET (none, 12 and 36 km)
and the use of surface and upper‐air meteorological observations in CALMET through NOOBS =
0 (“A” series, use surface and upper‐air observation), 1 (“B” series, use only surface
observations) and 2 (“C” series, don’t use any meteorological observations).
In addition, for each experiment using different CALMET model configurations, three CALPUFF
dispersion options were examined as shown in Table 3‐8. Two of the CALPUFF dispersion
sensitivity tests using dispersion based on sigma‐v and sigma‐w turbulence values using the
CALPUFF (CAL) and AERMOD (AER) algorithms. Whereas the third dispersion test (PG) uses
Pasquill‐Gifford dispersion coefficients.
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