Introduction

The ECMWF grib_api software library provides a set of functions/subroutines and command line tools for encoding and decoding WMO FM-92 GRIB edition 1 and edition 2 messages. The OpenIFS models use GRIB for its input and output files.

The grib_api software library must be built and installed before compiling any OpenIFS model that needs it.

If you have a version of grib_api on your system already that would most likely work, though check the minimum grib-api version required for each model.  It is recommended that you build and install grib-api as described below to ensure the correct configuration is used. Also, we recommend compiling your own to ensure the same compiler and compiler version is used for the model, as otherwise, error messages about conflicting module versions when compiling can arise.

For more information about grib_api, to download and install it please visit the grib_api website.

Before you start

Decide where you will put the grib_api package.

For a single user, grib_api might be installed in your home directory. For a multi-user environment, say a cluster or High Performance Computing Facility (HPCF), installing the grib_api package centrally once only is probably best and pointing your build configuration to this location.

In the walk-through example that follows, a single-user download and install is assumed.