FM 92 GRIB is widely used to represent forecast and analysis products in
binary. The GRIB specification is maintained and reviewed by the World
Meteorological Organisation (WMO), through its Commission for Basic 
Systems (CBS) and Working Group on Data Management.
The WMO make available the specifications of binary representation forms
such as GRIB within the publication WMO - No. 306 Manual on Codes,
Volume 1, International Codes, Part B - Binary Codes.

Deutsches Klimarechenzentrum (DKRZ) provides software as source code
to process GRIB data provided by the IPCC DDC. The following is a 
description of "grb2gas".

grb2gas is a program that creates GrADS descriptor and index files
for a given GRIB file distributed by the IPCC DDC. "grb2gas" is 
especially written for use in the framework of IPCC DDC. It must
NOT be used in other frameworks and therefore NO warranty is given
for any damage or data loss in conjuction with the usage of "grb2gas"
outside IPCC DDC.

Compile with

 cc -O -o grb2gas grb2gas.c -lm
or
gcc -O -o grb2gas grb2gas.c -lm

Usage

grb2gas -m grib_file_name \
        -r code_list_file_name \
       [-v]

where

  code_list_file_name is the name of the Code-List file
                      It is supposed to be in ASCII representation.
                      "TAB2vars.asc" is the file which is distributed
                      with the program.
  grib_file_name      is the GRIB input file name
  -v                  gives verbose output
 
"grb2gas" is a preparator for GRIB files to be used (read in) in GrADS.
The program scans through the GRIB file and stores information
about the structure of the file. With this information and the use of
the Code-List file, "grb2gas" creates a GrADS descriptor file and
a corresponding index file to be used by GrADS in conjunction with
the descriptor file. The program takes "grib_file_name" in order
to create file-names for the descriptor (grib_file_name.ctl) and
the index file (grib_file_name.gmp).
It only takes one call to "grb2gas" in order to create those files
from one specific GRIB file.

Assuming we have the GRIB file with the name "A" we can apply "grb2gas"
in the following manner

grb2gas -m A -r TAB2vars.asc 

"grb2gas" will then tell you what he has found in "A" in brief form
and what the files it creates are named. The new files will have the names
"A.ctl" (the descriptor file) and "A.gmp" (the index file).
You can then invoke GrADS by typing

grads -lc "open A.ctl"

and then let GrADS show you the contents or whatever.
In case of trouble feel free to call or send mail.
 
Good luck
 
------------- Deutsches Klimarechenzentrum GmbH ---------------
 
Arno Hellbach                      email: hellbach@dkrz.de
Deutsches Klimarechenzentrum       Tel +49 40 41173363         
Bundesstr. 55                      Fax +49 40 41173298         
D-20146 Hamburg
 
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