Hello everyone,
I have a question regarding the ICON-D2 template configuration in the Zonda portal.
In the Global Parameters window, I noticed that the icorotation parameter is set to 36°.
Could someone explain:
Why is the value 36° used for icorotation?
How does icorotation differ from icopole_lon?
What is the specific role of each parameter in defining the ICON grid?
Any clarification or reference to the documentation would be greatly appreciated.
Thank you very much!
Dear Raffaele,
icorotation, icopole_lat and icopole_lon are parameters which can be used to rotate pentagon points out of the domain of your interest. Since the 12 pentagon points of an icosahedron are sources of numerical instability, operational grids are rotated in such a way, that these points are outside the domain of interest (e.g. ICON-EU).
You can find a detailed description in chapter 2.1 section Pentagon Points of the ICON tutorial 2025 Wetter und Klima - Deutscher Wetterdienst - Our services - ICON Tutorial 2025
Those options should not be confused with the (domain-specific) settings pole_lon and pole_lat which are primarily used to recreate COSMO-model-like grids
Dear Drieger,
I understand now.
Thanks for the clarification!