Extend the possible interpolation methods for different grids (mostly ICON grid data)

[janhclem]

We already have interpolation functions and data structures for cartesian grids. Could we extend the interpolation functions to deal with icosahedral grids?

• Literature research: Can libraries be used for it?
• What routines can be shared with LaMETTA, YAC, ICON?
• Implement an icosahedral met grid type.
• Write a reading function for ico met type.
• Implement index search functions for the ICON grid.
• Implement a horizontal interpolation from the ICON grid to air parcel positions...
• Implement a horizontal interpolation from the ICON grid to the lat-lon support grid, which is required for parameterizations.
• Formulate a hybrid coordinate with potential temperature in the stratosphere and a non-hydrostatic coordinate in the troposphere.
• Generalize the vertical coordinate system in MPTRAC.
• Implement exact interpolations for winds on pressure levels that consider the tilt of the levels against the eta coordinate.
• Implement the vertical interpolation function and combine it with the horizontal interpolations.
• Implement a control flow to select between cartesian, icosahedral or any other potential grid geometry.
• Test the procedures with ICON output data...

[lars2015]

Hi Jan, maybe check whether there are interpolation functions/code available from ICON which could be used?