UPP Online Tutorial for UPPV4.1 | Visualization: GEMPAK

The GEMPAK utility nagrib is able to decode GRIB files whose navigation is on any non-staggered grid. Hence, GEMPAK is able to decode GRIB files generated by the UPP package and plot horizontal fields or vertical cross sections.

A sample script named run_unipostandgempak, included in the /UPPv4.1/scripts directory, can be used to run unipost, copygb, and plot the following fields using GEMPAK:

  • Sfcmap_dnn_hh.gif: mean SLP and 6-hrly precipitation
  • PrecipType_dnn_hh.gif: precipitation type (snow and rain only)
  • 850mbRH_dnn_hh.gif: 850 mb relative humidity
  • 850mbTempandWind_dnn_hh.gif: 850 mb temperature and wind vectors
  • 500mbHandVort_dnn_hh.gif: 500 mb geopotential height and vorticity
  • 250mbWindandH_dnn_hh.gif: 250 mb wind speed isotacs and geopotential height

This script can be modified to customize fields for output.

In order to use the script run_unipostandgempak, it is necessary to set the environment variable GEMEXEC to the path of the GEMPAK executables. For example:

setenv GEMEXEC /usr/local/gempak/bin

Additional information on GEMPAK, including a manual and installation guide can be found at http://www.unidata.ucar.edu/software/gempak