Table of Contents - The Atmospheric Studies Group at TRC

Section 9: CALPUFF
9.8 User-Specified Deposition Velocity Data File (VD.DAT)
The CALPUFF model requires that the user specify the method for determining dry deposition velocities
for each species. In Input Group 3 of the control file, one of the following flags must be specified for
each pollutant.
0 = no dry deposition (deposition velocities set to zero)
1 = resistance model used - pollutant deposited as a gas
2 = resistance model used - pollutant deposited as a particle
3 = user-specified deposition velocities used
Note that different methods can be used for different pollutants in the same CALPUFF run.
If any species are flagged as using "user-specified" deposition velocities, CALPUFF reads a formatted
user-prepared data file with a 24-hour diurnal cycle of deposition velocities for each species flagged. The
24 values correspond to hours 01-24 (LST) of the simulated day. Twenty-four values must be entered for
each flagged pollutant, even if the model run is for less than a full diurnal cycle. The units of the
deposition velocities are m/s.
An example of a user-specified VD.DAT file is shown in Table 9-34. The VD.DAT file uses a control
file format (see Section 9.1). All text outside the delimiters (!) is considered as user comment information
and is echoed back but otherwise ignored by the input module. Each data line consists of a delimiter
followed by the species name, 24 deposition velocities, and a terminating delimiter. The data may extend
over more than one line. The line being continued must end with a comma. The control file format
allows the use of repetition factors (e.g., 3 * 1.0 instead of 1.0, 1.0, 1.0). The order in which the species
are entered in the file is not important. However, the file must end with an input group terminator (i.e.,
!END!).
The model checks that values have been entered for each species flagged as using user-specified
deposition velocities. An error message is printed and execution of the run is terminated if any values are
missing. The run will also terminate with an error message from the input routine if too many values are
entered (i.e., more than 24 values for a particular pollutant). The species names must match those used in
the chemical mechanism of the model.
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