enable remapping of landice restarts (from CF to EASE) via ldas_setup

[biljanaorescanin]

@weiyuan-jiang created a fix so we can remap landice restart files from CF to EASE tile space via ldas_setup.

More details:
Currently, this is the only way to obtain a starting point for Land-Ice EASE grid simulations with GEOSldas. It may actually be a better approach, since it allows the use of any CF restart file.
The RESTART:M option is not working because the MERRA2 restart files have been moved from the archive. This issue should be resolved eventually, with only days 14 and 28 available as options. Until then, this method is required to initialize EASE grid Land-Ice runs.

Successfully 0-diff tested by @gmao-rreichle on 25 Nov 2025

[biljanaorescanin]

For testing 1day global case run was done from C90 to EASE M36 using (model_tests_with_landice/HISTORY_1d.rc).

[biljanaorescanin]

Let me sum current issue we have here for records:

It looks like land-ice group plan is to run land-ice only experiments (tile type 20). And then use that restart to remap and start new exp on diff grid?

In that configuration we cannot use ldas_setup with RESTART:2 to remap, because:

ldas_setup expects both tile types 100 (land) and 20 (land-ice) to be present in the input restarts in order to create a new restart on a different grid.

If I follow Devon’s example and try to run ldas_setup with just a type-20 restart on the M09 EASE grid, preprocessing completes (catparam/domain are created), but no mapping file or restart is created, and ldas_setup eventually crashes with a TypeError: expected str, bytes or os.PathLike object, not NoneType when it tries to find the input restart path (self.in_rstfile is None because the restart wasn’t created).

So the practical implication is:

To remap from C1440 to something like M09 using ldas_setup as currently implemented, we need a run that includes both tile types 100 and 20, so that both land and land-ice restarts exist at the end of the run.

After ldas_setup is used with those combined restarts, you can still run only land-ice going forward if you want the dual tile requirement is just for the restart/remap step.

Alternatively, ldas_setup itself would need to be modified to support starting from land-ice only restarts.

Bottom line: with the current code, the existing land-ice only experiments (type 20 only) cannot be used as RESTART:2 sources for remapping; we need at least one spinup with both tile types or a change to ldas_setup.

@weiyuan-jiang this is just a summary of what we found on from Teams chat. Where starting point was Devon's run.

[weiyuan-jiang]

@lcandre2 , Now this branch should support setup with only landice