Generic Guidance and Optimum Model Settings for the CALPUFF ...

Table A-4. Explanation and Recommendations for the List of Key CALUFF Model Options
Option
Technical Options - Input Grp 2
Vertical distribution used in the near
Parameter Recommended
value
Explanation and Justification
field
MGAUSS 1 Always use
Terrain adjustment method MCTADJ 3 Partial plume path adjustment
Usually 0, but does allow for CTDM-like treatment of sub grid scale hills (See input
Sub grid-scale complex terrain MCTSG
0 Group 6)
Default is not to use slug model. But it is the recommended approach for area sources
Near-field puffs modeled as slugs MSLUG
0 with receptors in the very near field or for time-varying emissions such as accidental
releases are modeled.
Transitional plume rise MTRANS 1 Yes, always allow transitional rise
Yes, always allow stack tip downwash. It becomes important if ratio of stack gas exit
Stack tip downwash
MTIP
1 velocity to wind speed is < 1.5
Method to compute plume rise for
point sources not subject to
downwash
Method to simulate building
downwash
Vertical wind shear modeled above
stack top
MRISE
MBDW
MSHEAR
1
2
0
Yes, to Briggs plume rise (1). The other option (2) is meant for very hot sources such
as flares where the Bousinesq equation is no longer valid and plume rise needs to be
treated numerically
PRIME Method unless long such as aluminum smelters with aspect ratios of L/W
over 5-10. For these situations use MBDW=1 (ISC/BLP downwash method)
The default is for no vertical wind shear. The model inherently includes variable flow
in the vertical from the upper air data. If this option is used the model applies a
power law wind speed profile above stack top.
Puff Splitting allowed MSPLIT 0 No puff splitting. In long range transport, puff splitting may be necessary. In shortrange
modeling, MSPLIT=0 is recommended.
Chemistry to be modeled and transformation rates are computed internally using
Chemical transformation
MCHEM
1 MESOPUFF II scheme (recommended when dealing with SO2, SO4, NOx, HNO3
and NO3 concentration predictions over 10-20 km or more.
Aqueous phase chemistry MACHEM 0 Aqueous phase chemistry (option is not currently active)
Wet removal modeled MWET 1 Wet deposition is often important long range transport. May be used in near-field in
certain circumstances. Depends on the pollutant characteristics.
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