This article relates to GRIB edition 2
Step-by-step guide
To convert multi-field GRIB messages into single-field, you can use the grib_copy command.
For example here we have a multi-field GRIB2 file with 30 messages some of which contain several fields. The grib_copy command creates a new file in which every message has a single field:
% grib_copy multi.grib2 single.grib2 % grib_count multi.grib2 30 % grib_count single.grib2 56
The use of the multi-field feature is not recommended.