Table of Contents - The Atmospheric Studies Group at TRC

Section 8: CALMET Model Files
If the wet removal algorithm of the CALPUFF or MESOPUFF II models is to be applied, CALMET must
produce gridded fields of hourly precipitation rates from observations. The PXTRACT and PMERGE
preprocessing programs process and reformat the NWS precipitation data in TD-3240 format into a
formatted or unformatted file called PRECIP.DAT. The output file of PMERGE is directly compatible
with the input requirements of CALMET. The user needs to set the precipitation file format variable,
IFORMP, in the CALMET control file to one when using PMERGE unformatted output. Otherwise, set
IFORMP to two for a formatted file either prepared by the user or generated by PMERGE. This option is
provided to allow the user an easy way to manually enter precipitation data for short CALMET runs.
A sample free-formatted PRECIP.DAT file is shown in Table 8-15. A description of each variable in the
formatted surface data file is contained in Table 8-16. The first line of the file identifies the file and its
format to CALMET. The second line provides the number of comment lines (character strings of up to
80 characters in length) to follow that are read but are not interpreted by the model. One of these may
typically contain a title to identify the data set. The next line after all comment records identifies the map
projection for any locations provided in the file. Presently, the projection is NONE as no locations are
provided. The next record identifies the time zone of the data in the file, which is denoted as the time to
add to UTC (e.g., the Eastern Standard Time zone in the USA is UTC-0500). The next line identifies the
beginning and ending dates and times of data in the file, the reference time zone for these, and the number
of stations. Finally, one record per station follows with the station ID for each. One data record must
follow for each hour. Each data record contains the date and time and the precipitation rate (mm/hr) for
each station.
8-81