Train for ERA5 stratosphere only

[jpolz]

The purpose of this is to discuss the experimental setup and some results

[jpolz]

assign me

[github-actions]

Issue assigned to @jpolz.

[jpolz]

Documenting the experimental setup in https://github.com/ecmwf/WeatherGenerator/pull/484/files
I will start a run using 24h on 8 nodes from hclimrep.

[clessig]

Documenting the experimental setup in https://github.com/ecmwf/WeatherGenerator/pull/484/files I will start a run using 24h on 8 nodes from hclimrep.

Please do not use more than 2 nodes for the time being.