Meteorological data files are available from a variety of sources. However, most will need to be reformatted for use by HYSPLIT. The Meteorology / Convert to ARL menu tab provides several options that will be discussed briefly below. These data can be in Gridded Binary Format (only GRIB-1 is supported through the GUI), Network Common Data Form (NetCDF), or custom binary formats, such as from NCAR's MM5. A conversion program (API2ARL) from GRIB-2 to the HYSPLIT input format can be found in the data2arl directory. Local compilation is required to use these programs. The HYSPLIT data conversion is necessary because each meteorological model may contain different variable names, data organization, horizontal grid projection, or vertical coordinate systems. Keeping the meteorological pre-processing external to HYSPLIT provides more stability to the base code structure. Note that some of the data conversion programs are only available for UNIX systems.
HYSPLIT requires meteorological data on an evenly spaced grid (latitude-longitude or conformal projection) at multiple heights and time periods over the duration of the simulation. These data can be obtained from various sources already formatted for use by HYSPLIT or converted by each user to the proper format. As noted earlier, the source code for most of the data conversion programs is available in the \hysplit\data2arl directory.