Table of Contents - The Atmospheric Studies Group at TRC

Section 2: Geophysical Data Processors
2. GEOPHYSICAL DATA PROCESSORS
The GEO.DAT data file contains the geophysical data inputs required by the CALMET model. These
inputs include land use type, elevation, surface parameters (surface roughness length, albedo, Bowen
ratio, soil heat flux parameter, and vegetation leaf area index) and anthropogenic heat flux. The land use
and elevation data are entered as gridded fields. The surface parameters and anthropogenic heat flux can
be entered either as gridded fields or computed from the land use data at each grid point. A series of
programs have been developed to process the terrain and land use data and produce a GEO.DAT file
containing gridded fields of terrain, land use, and land use weighted fields of surface parameters and heat
flux. Creating the GEO.DAT is a three step process. The first two steps involve processing the relevant
terrain and land use data and then, in the third step, the processed files are combined into a final file
(GEO.DAT) that can be read by CALMET. The following preprocessors are used to generate a
GEO.DAT file:
TERREL
is a terrain preprocessor which coordinates the allocation of terrain elevation
data from several digitized data bases to a user-specified modeling grid.
CTGPROC
is a land use preprocessor which reads the following datasets; (1) compressed
Composite Theme Grid (CTG) land use data, (2) USGS Global LU Dataset, (3)
National Land Cover Data set, (4) a generic format where specific Land Use
categories are mapped internally to USGS Land Use categories and (5) a
second generic format which allows the user to use any Land Use categories
and map accordingly. CTGPROC computes the fractional land use for each
grid cell in the user-specified modeling domain. If required, the preprocessor
CTGCOMP, can first be used to compress the data file format of a USGS land
use data file in Composite Theme Grid (CTG) format prior to using
CTGPROC.
MAKEGEO
is the final preprocessor which reads the fractional land use data, user inputs
which define land use category mapping, and values relating each of the surface
parameters to land use and optionally, the gridded terrain file, and produces a
GEO.DAT file ready for input to CALMET. Note: if the gridded terrain data
file is not incorporated into MAKEGEO, it must be hand-edited into the
GEO.DAT file before running CALMET.
The complete process is illustrated in Figure 2-1 and further described in the following sections.
2-1CALPUFF_Version6_UserInstructions.doc