== GRIB library ==

FLEXPART expects meteorological input files to be in GRIB format, thus a GRIB decoding library is needed. GRIB is a compressed binary format for meteorological fields including metadata, defined by [http://www.wmo.int/pages/prog/www/WMOCodes/WMO306_vI2/VolumeI.2.html WMO].

There is `GRIB1` and `GRIB2` format. Since V8.0, FLEXPART can read GRIB2 (as well as GRIB1). Current operational NCEP GFS model data are disseminated in the GRIB2 format. 

A recommended GRIB library implementation is ECMWF's [https://software.ecmwf.int/wiki/display/GRIB/Home GRIB_API]. A Version >= 1.6.1 is needed for reading GRIB2 data. It can read the GRIB1 format as well. For backward compatiblity, the EMOS GRIB library can still be used (although it can only work with GRIB1 data).

Recommended sources for GRIB libraries:
  - [https://software.ecmwf.int/wiki/display/GRIB/Home ECMWF GRIB_API]
  - [http://rda.ucar.edu/libraries/grib/ UCAR GRIB library]