1. 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

2. Handling CCSDS compression

$ grib_set -r -w packingType=grid_ccsds -s packingType=grid_simple ccsds.grib grid_simple.grib

3. 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. 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.

All other steps, starting from running ungrib.exe to wrf.exe should be run as usual.