Table of Contents - The Atmospheric Studies Group at TRC

Section 1: Introduction
1.5 Summary of Data and Computer Requirements
CALMET Data Requirements
The input data requirements of the CALMET model are summarized in Table 1-3. The modeling system
flow diagrams (Figures 1-1 through 1-4) provide an overview of the various input data sets required by
the model as well as the preprocessing steps used to produce them. CALMET is designed to require only
routinely-available surface and upper air meteorological observations, although special data inputs can be
accommodated. For example, twice-daily sounding data (e.g., at the standard sounding times of 00 and
12 GMT) are needed as a minimum, but if soundings at more frequent (even arbitrarily spaced) intervals
are available, they will be used by the model.
CALMET reads time-varying surface observations of wind speed, wind direction, temperature, cloud
cover, ceiling height, surface pressure, relative humidity, and precipitation type codes (optional, used only
if wet removal is to be modeled). Hourly measurements of these parameters are available from National
Weather Service surface stations. The preprocessors are designed to use data in the National Climatic
Data Center's (NCDC) standard data formats (e.g., CD-144 format for the surface data). However, the
data can also be input into the model by way of free-formatted, user-prepared files. This option is
provided to eliminate the need for running the preprocessors to prepare the data files for short CALMET
runs for which the input data can easily be input manually.
Missing values of temperature, cloud cover, ceiling height, surface pressure, and relative humidity at
surface stations are allowed by the program. The missing values are internally replaced by values at the
closest station with non-missing data. However, one valid value of each parameter must be available
from at least one station for each time period of the run. Missing values of the precipitation code are
passed through to the output file, since CALPUFF contains logic to handle missing values and CALGRID
does not use this parameter.
The upper air data required by CALMET include vertical profiles of wind speed, wind direction,
temperature, pressure, and elevation. As noted above, routinely-available NWS upper air data (e.g., in
TD-5600 and TD-6201 format) or non-standard sounding data can be used. The use of non-standard data
formats would require a user-prepared reformatting program to convert the data into the appropriate
CALMET format.
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