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Data_override:: Issue with reading the grid file in data_override when using 0:180:-180:0 grids #1537

Open uramirez8707 opened 1 month ago

uramirez8707 commented 1 month ago

Describe the bug Grid files that have longitude to ranges from 0 to 180 then -180 to 0 are not being read correctly by data_override when using "OCN" and "ICE" grids.

The code gets here: https://github.com/NOAA-GFDL/FMS/blob/460c5921249a2c872135bf3f37d57fe498bde93d/data_override/include/get_grid_version.inc#L218-L224

At the dateline, it will use values around -180 and 180 and average those which will cause bad longitudes. You can see the issue in this file: ncview /gpfs/f5/gfdl_f/scratch/Uriel.Ramirez/REGIONAL_MODEL/FMS/build/test_fms/data_override/LineOfWeirdness_Test /grid_read_in_ocn.nc

MOM6 seems to use the centroids when it reads its grid: https://github.com/NOAA-GFDL/MOM6/blob/8ecb2603119b8c9d4dee9ee6b174e1864415d1cc/src/initialization/MOM_grid_initialize.F90#L220-L222

To Reproduce This Test reproduces the error: https://github.com/uramirez8707/FMS/blob/LineOfWeirdnessTest/test_fms/data_override/test_data_override_LOW.F90

The data files to run it can be found here: /gpfs/f5/scratch/Uriel.Ramirez/gfdl_f/REGIONAL_MODEL/FMS/build/test_fms/data_override/LineOfWeirdness_Test

Expected behavior The grid file should be read correctly by data override. We should either:

  1. Read the centroids from the file directly
  2. Add logic to the averaging to deal with this corner case
  3. Model components can pass in their own lat/lon to use by data_override

System Environment This happens in any system

Additional context This was seen by @theresa-morrison and @kshedstrom