All ECMWF operational model output and ERA-40 data have been archived in the GRIB format. ECMWF used its own local extensions for the parameter code tables. The version of code Table 2 used by ECMWF include:

• Version 128 - describes most of the standard variables.
• Version 162 - for the vertical integrals, net and radiative tendencies, chemical model transport and variances and covariances.
• Version 140 - describes the wave model output.

There are several utilities/software packages available for decoding and regridding GRIB data. These include:

1. DSS Created FORTRAN programs - A suite of programs for decoding and regridding the ECMWF GRIB data.

2. WGRIB - This is a utility,created by Wesley Ebisuzaki (of NOAA/NCEP), that primarily decodes and reformats GRIB data.

3. NCL - The NCAR Command Language is a powerful utility designed specifically for data access, analysis and visualization. NCL can also regrid and reformat the data into NetCDF. Many application examples are available for NCL. Please go here for assistance with NCL.

4. GrADS - The Grid and Analysis Display System is an interactive tool that is user for data access, analysis and visualization.

5. A grib reader for MATLAB is also available.

Tips on Utility Selection
Regridding
The DSS created programs and NCL are the most powerful tools for regridding the data, and more specifically, handling the spectral transformations and interpolation of the reduced gaussian grids to regular latitude-longitude grids.

Decoding
If you mostly need to decode and reformat the data, WGRIB is an easy utility to learn and use.

Visualization
GrADS and NCL are good utilities for visualization, however, GrADS does not perform spectral transformations.