How to download ECMWF' Open Data forecast required to initialise WRF model
ECMWF AIFS Open Data: real-time forecasts
https://www.ecmwf.int/en/forecasts/datasets/open-data
Handling CCSDS compression
$ grib_set -r -w packingType=grid_ccsds -s packingType=grid_simple ccsds.grib grid_simple.grib
Running WPS
In Open Data all fields are in GRIB2 format. GRIB2 encoding of soil moisture and temperature cannot be processed by WPS since the original codes were designed for old, GRIB1 encoding where temperature and moisture for each underground layer was represented by different variable. In Open Data GRIB2, Soil Temperature and Volumetric soil moisture are represented as single variables on four different levels (soil Layers). Solution to handle such changes proposed on WRF user forum: https://forum.mmm.ucar.edu/threads/change-in-soil-variables-from-ecmwf-cycle-49r1.19864/page-4 and it works correctly with rd_grib2.F provided by figurski on 8.4.2025. User should download this file to replace the original file in "WPS/ungrib/src/" directory and re-compile WPS with the new file. Note that with this solution users need a separate ungrib.exe for handling GRIB2 Open Data files.
Aside from separate ungrib.exe, special Vtable is needed to process Open Data which can be downloaded from here Vtable.ECMWF_GRIB2_opendata.
Model configuration is here:
/perm/usbk/wrf/run_IFS_4km_opendata/
The two files not yet in WRF official release required to process the Open Data are in the directory above:
rd_grib2.F this is modified file and would replace file with the same name in:
/perm/usbk/wrf_module/4.6.1_grib2/WPS-master/ungrib/src/
- Vtable.ECMWF_GRIB2.txt is updated table with ECMWF' GRIB2 definitions
Since one of the ungrib programs needs to be modified, I have a separate installation of WRF for ECMWF' GRIB2 in:
/perm/usbk/wrf_module/4.6.1_grib2/
This still hasn't been added to official WRF release. Relevant external links:
https://forum.mmm.ucar.edu/threads/change-in-soil-variables-from-ecmwf-cycle-49r1.19864/page-2
https://github.com/wrf-model/WPS/issues/264