GeorgeGayno-NOAA
commented
10 months ago It was decided to make the read routine backwards compatible, i.e., it should work with coldstart files created from the current or the future (fractional grid) versions of chgres_cube. A global attribute was added to the coldstart files to indicate which version of chgres created it (see https://github.com/GeorgeGayno-NOAA/UFS_UTILS/commit/24fe48a9cb1919e4527221f177d35765049e85d6)
The read routine was updated at aba1b3c to read either version. It was tested on the "control_c48_intel" regression test. Both versions of the coldstart files were tested. In both cases the model ran to completion with no problems.
Description
The introduction of fractional grids required new surface-specific variables for roughness length, snow depth/liquid equivalent, column temperature, and skin temperature. For example, roughness length is stored in three separate variables: zorll (land), zorlw (open water) and zorli (ice). There is also a 'composite' or 'merged' roughness record, zorl.
The i/o module (fv3atm_sfc_io.F90) will read in a composite field (mandatory) from the coldstart file and optionally the surface-specific fields. If the surface-specific fields are not in the file, the module will populate them from the composite value. This allows for cold starting with files from the current version of chgres_cube.
Solution
The chgres_cube program has been updated to recognize fractional grids. As part of this update, it will always output the surface-specific records. Update the model i/o module to read them, then, compute the composite field (some composite fields are used by the physics).
Testing:
So far, tested on Hera with the following configurations:
Dependent issues:
https://github.com/ufs-community/UFS_UTILS/issues/123