Table of Contents - The Atmospheric Studies Group at TRC

Section 9: CALPUFF
9.12 CTDMPLUS Terrain Feature Description and Receptors (HILL.DAT, HILLRCT.DAT)
CALPUFF allows two ways of specifying the characteristics of terrain features modeled by CTSG. The
first is by means of the OPTHILL processor described in Section 9.15, which provides the parameters to
be entered in the control file CALPUFF.INP. The second approach allows the use of the terrain
preprocessing programs provided with CTDMPLUS (Mills et al., 1987). If a user is familiar with the
terrain preprocessor, then this may be the preferred option because the standard terrain file used in
CTDMPLUS, "TERRAIN", can be read by CALPUFF without modification. CTDMPLUS subroutines
that read and process the terrain data have been incorporated in CALPUFF. Similarly, CTSG receptors
may either be entered directly into the control file, or may be read from the corresponding CTDMPLUS
"RECEPTOR" file. Note however that any CTSG receptors that are not located on one of the hill features
(designated by a hill ID of 0) are ignored in CALPUFF. The default filenames in CALPUFF for
TERRAIN and RECEPTOR are HILL.DAT and HILLRCT.DAT, respectively, and they are used together
so that both must be used if the CTDMPLUS input option is selected.
Table 9-40 illustrates a typical HILL.DAT file for one hill. This one is defined by ellipse/polynomial
shapes determined for a range of 10 "critical elevations" from 25 m to 115 m above the base of the hill.
After the header record, the first group of 10 records provides the ellipse parameters at each "critical
elevation", and the second group of 10 records provides the parameters for the corresponding inverse
polynomial shape profile fit to the portion of the hill above it. Refer to Mills et al. (1987) for more
detailed information. Table 9-41 shows a typical HILLRCT.DAT file. Data for each CTSG receptor are
placed in one record, and identify the location, hill number (ID), ground elevation, and receptor height
above the ground. Note that CALPUFF places all receptors on the ground. The structure of the data
records is defined in Table 9-42 (HILL.DAT) and 9-43 (HILLRCT.DAT).
Other data associated with the HILL.DAT and HILLRCT.DAT are provided in the CALPUFF.INP
control file, in Input Group 6. These reference the coordinate system used to prepare the CTDMPLUS
simulation to the system chosen for the CALPUFF simulation. XHILL2M and ZHILL2M are the
conversion factors that scale the CTDMPLUS "user units" in the horizontal and vertical, respectively, to
meters. XCTDMKM and YCTDMKM define the location of the origin of the CTDMPLUS coordinate
system in the CALPUFF coordinate system. The units used for this are kilometers. Hence, if UTM
coordinates are used for both simulations, the origins of the two system are the same, and XCTDMKM =
YCTDMKM = 0.
9-222