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@havardhhaugen havardhhaugen commented Oct 21, 2025

For Netcdf output on a projected grid; rotate the winds such that 10u and 10v align with x and y in the projected coordinate system.
Current implementation:

  • Uses the transformation from aifs-support (inverted)
  • Used by default, no config option to not use (if self.proj4 is set)
  • Only done for 10m winds.

Inverse transformation seems to be exact, we recover meps x and y winds in the analysis:
Screenshot from 2025-10-21 09-31-52

@havardhhaugen havardhhaugen linked an issue Oct 21, 2025 that may be closed by this pull request
@havardhhaugen havardhhaugen requested a review from tnipen October 21, 2025 07:43
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Changed the code to use precomputed rotation matrices, which required re-implementing the rotate function. Also generalized to rotate any field in a list defined in Metno conventions. Currently contains windspeed at all pressure levels along with 10, 100m.

Checked that the new rotate function works as intended
Screenshot from 2025-10-22 12-59-22

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Output x and y wind in projected coordinates

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