AIFS static fields timestamp

AIFS, IFS and OpenIFS
1

I’m trying to reproduce AIFS forecasts. I’m wondering which timestamp to download for the static fields.

In particular I try to run AIFSv1.1 which requires static variables lsm, slor, sdor, and z_sfc, essentially all about orography. But the root of the question is independent of model version.

I see multiple ways to get slightly different static fields, especially over poles and mountain ranges:

  • CDSAPI for dates 1940 (ERA5), 1979 (training start date), 202x (training end or recent)
  • opendata

Which static variables timestamp were used for training and hence should be used for inference? Found no exact mention in the papers or docs.