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ECMWF makes available a GRIB decoding library (GRIB-API) for the benefit of the WMO community. GRIB-API can be freely downloaded from here and the documentation can be found here. The GRIB-API provides a simplified access to GRIB2 headers through a set of virtual keys documented here

GRIB2 encoding details

UERRA-GRIB2 checking tool

The so called tigge_check tool is a part of GRIB-API package. It should be used to validate all GRIB2 files prepared for UERRA (the option -u). The tool is checking all encoding details so that only fully compliant UERRA files following exactly required definitions would pass. It can check also allowed value ranges for each parameter if used with the option -v. These ranges have not been fully defined for all UERRA parameters yet e.g. for radiation fluxes. Sometimes warnings about values exceeding expected limits do not mean error in the checked data but only model specific correct values. 

Examples of tigge_check usage:

# example with one data value ranges warning and one encoding error
> tigge_check -u -w -v *.grib2
> warning: an.enda.tcw.sfc.0.fp.grib2, field 1 [total_column_water_sfc]: total_column_water_sfc maximum value 31.5638 is not in [50,150]
  => [31.5638,150]
> fc.oper.2t.sfc.2.grib2 , field 1 [temperature_hl]: invalid height level 3

GRIB2 encoding details

The complete WMO compliant GRIB2 definitions of all UERRA parameters are linked here.

The additional generally required encoding UERRA details are listed below:

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*disregard data values in this grib (some step/level values were created artificially as real data has not been available yet)