Add ISSM fields to HISTORY and initialization arguments

[agstub]

The purpose of this Draft PR is to add new variables from ISSM (Ice-Sheet and Sea-Level System Model) to HISTORY. The variables are:

Inputs to ISSM from GEOS:

• ICESMB (ice surface mass balance: calculated in LandIce GridComp; imported by ISSM GridComp for input to ISSM). This can be included in HISTORY in either a LANDICE collection (grid or landice tiles) or ISSM collection (mesh tiles). Apart from the spatial representation, the mesh version is time-averaged between ISSM time steps so that it corresponds to the forcing that ISSM 'feels' (i.e. the values used in ISSM mass conservation solver).

Outputs from ISSM:

• ICESURF (ice surface elevation), ICETHICK (ice thickness), and ICEVEL (ice flow speed)

• Development by @weiyuan-jiang for outputting these variables with HISTORY on a tile space that corresponds to the (unstructured, triangular) elements of ISSM's mesh. Feature/jiang/issm gridcomp GEOSgcm_GridComp#1209

• added new collection tavg24_1d_issm_Nt (Tile-space,Daily,Time-Averaged,Single-level,ISSM Diagnostics) for mesh tile space. 81842f0

• Added default ISSM outputs ICETHICK, ICEVEL, and ICESMB (time averaged between ISSM time steps) defined on mesh tiles. An ISSM module update will be required for ICETHICK and ICEVEL (the ISSM branch is ready) for ISSM to fill out the 'outputs' pointer completely---until then they are just filled in with zeros automatically on the GEOS side. Add new issm exports/outputs GEOSgcm_GridComp#1210

• The PR also adds configuration parameters to GEOSldas_LDAS.rc that are required by ISSM for initialization: ISSM_EXPDIR and ISSM_EXPNAME. ISSM_EXPDIR points to the directory containing the ISSM input file, which will be replaced by a restart directory in the future. ISSM_EXPNAME is the name of the binary input file (ISSM_EXPNAME.bin) and PETSc options file (ISSM_EXPNAME.toolkits).

• With the new mesh tile output, I don't know if it's still possible to output the ISSM variables (ICESURF, ICETHICK, ICEVEL) on a 2d, structured grid. This was easy before because the underlying tile space for export was the landice tiles, so 2d output was possible. Now that the ISSM gridcomp's underlying locstream has been changed for the mesh output (and grid-->1d mesh grid)---is this somehow still possible?

• Maybe a non-issue: we need to have a 2d glacier collection in HISTORY or LDAS+ISSM crashes. perhaps because the grid is ultimately inherited from history (and ISSM needs an attached grid to transform from landice tiles to mesh)?

Related issues and PRs

• Original issue: GEOSldas+ISSM on Discover GEOSldas#853
• Add ISSM components to LDAS fixture GEOSldas#854
• Add ISSM ice sheet model GridComp to Landice GEOSgcm_GridComp#1203

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[weiyuan-jiang]

The variables in the same collection should have the same tile or gridded space. We have discussion that ISSM should have output in mesh-like space. So ICEEL should not be in this collection

[agstub]

The variables in the same collection should have the same tile or gridded space. We have discussion that ISSM should have output in mesh-like space. So ICEEL should not be in this collection

That makes sense! Should I make new collections for ISSM outputs (mesh tile collection and gridded collection)? Will we still want to save a gridded version of ice elevation @lcandre2 ?

[lcandre2]

The variables in the same collection should have the same tile or gridded space. We have discussion that ISSM should have output in mesh-like space. So ICEEL should not be in this collection

That makes sense! Should I make new collections for ISSM outputs (mesh tile collection and gridded collection)? Will we still want to save a gridded version of ice elevation @lcandre2 ?

I would say that for standard ISSM outputs (elevation, ice velocity, ice discharge, perhaps a few others) it would be good to have both a tile and gridded collection.