Identifying coordinate system of Wetterzentrale maps?

Question

I'm trying to georeference two maps from wetterzentrale in ArcGIS Desktop.

In what coordinate system are those maps created?

Answer 1

As commented by @mkennedy a guess might be:

north pole-centered stereographic with a central meridian/longitude of origin around -20

Otherwise I think you will be best to try and contact the author(s) of the maps.