FMS 2025 does not support our fvdycore

[mathomp4]

As noted in the release notes of FMS 2025.01:

• MPP_IO/FMS_IO: A deprecation warning will now be output when using these modules or enabling the -Duse_deprecated_io flag via the build systems. Usage of these modules will be deprecated in the next release. (Fms io deprecation warning NOAA-GFDL/FMS#1609)

And as our fvdycore is out of sync (in some ways) with the mother repo, we still use the old deprecated IO layers. Thus, FMS 2025.01 might be the last time we can update the fvdycore in GEOS until we update to the latest IO.

From what I can see of the mother repo, this PR by @laurenchilutti:

NOAA-GFDL#74

is at least a starting point to see what the changes needed are.

But, the changes are in bits of fvdycore I'm a bit hesitant to go near. Thus, I've added @wmputman as an assignee. Perhaps he can figure out how to integrate these changes into our fvdycore so that we can continue to use FMS 2025+

[mathomp4]

Even worse, our FV3 cannot even use 2025+ as our code is so old we are still referring to mosaic1 and that is now removed in favor of mosaic2

[laurenchilutti]

@mathomp4 I have a few PRs that have addressed outdated FMS functions in the dycore that I hope wouldn't be too difficult to cherry-pick into this GEOS-ESM fork:

• From Jan 2020: Updates needed for fms2_io NOAA-GFDL/GFDL_atmos_cubed_sphere#15
• From April 2021: Removing a duplicate use statement of FMS function "write_version_number" NOAA-GFDL/GFDL_atmos_cubed_sphere#98
• From May 2021: Fms2 io implementation NOAA-GFDL/GFDL_atmos_cubed_sphere#74
• From June 2021: Typo fix in fv_io.F90 NOAA-GFDL/GFDL_atmos_cubed_sphere#111
• From April 2023: Deprecatedio removal NOAA-GFDL/GFDL_atmos_cubed_sphere#257
• From Sep 2023: tools/fv_io: fix a few minor errors NOAA-GFDL/GFDL_atmos_cubed_sphere#284

The biggest changes were in May 2021 PR 74, which you mention in this Bug's description.

And the mosaic1->2 changes are in PR 257 and not too complex.

[mathomp4]

@laurenchilutti Thanks. Though "not too complex" given the age of our fvdycore... eeeeeeeee...

Hopefully we can get there "soon".