updates zaerosol in snow with mpassi

[njeffery]

[x] Short (1 sentence) summary of your PR:
Merge aerosol related changes from MPAS-SI into Icepack
[x] @njeffery @eclare108213
[x ] Suggest PR reviewers from list in the column to the right.

• Please copy the PR test results link or provide a summary of testing completed below.
  ENTER INFORMATION HERE
• How much do the PR code changes differ from the unmodified code?
  • [x ] bit for bit with zbgc off
  • different at roundoff level
  • more substantial
• Does this PR create or have dependencies on CICE or any other models?
  • Yes
  • No
• Does this PR add any new test cases?
  • Yes
    -[x] No
• Is the documentation being updated? ("Documentation" includes information on the wiki or in the .rst files from doc/source/, which are used to create the online technical docs at https://readthedocs.org/projects/cice-consortium-cice/.)
  • Yes
  • [ x] No, does the documentation need to be updated at a later time?
    • Yes
    • No
• Please provide any additional information or relevant details below:
  Replaces snow updates for vertical BGC aerosol code in Icepack with MPAS-SI version, which requires a new parameter, and updates related shortwave code from the same commit. The original aerosol tracer code is unchanged. The new parameter has yet to be implemented.

icepack_aerosol.F90

Replaces contents of subroutine update_snow_bgc. The new subroutine argument bio_index_o is commented out until the call in ice_algae.F90 is also updated.

icepack_parameters.F90

adds hs_ssl_min with a hard-coded value. Does this need to be in namelist?

icepack_shortwave.F90

updates icegrid calculation (for zbgc) as in https://github.com/E3SM-Project/E3SM/commit/e885a850330ba4cf8ebc63f82c48ecf36aef50e5

[njeffery]

@eclare108213 : I merged your PR with the latest Icepack integration version. It's still not tested but wanted to make it available for testing in CICE and Icepack. Let me know if I should change this PR to draft.

[eclare108213]

Cool. You can leave this one open (change to draft if you prefer), and I'll close the other one. I'll help after I move the constants.

[eclare108213]

@njeffery What's the status here? And @apcraig what's the best path forward - should we merge into the E3SM fork or into the Consortium?

[njeffery]

@eclare108213 : I think it still needs to be tested in Icepack. I'm not waiting on it though. I'm continuing from here with new modifications to Icepack for zaerosols and zbgc.

[apcraig]

I'm open about the process. Maybe this should just be incorporated with the zaerosols and zbgc changes coming in the future? Or is the important enough to do as a separate PR?

Unless this needs to be in the E3SM PR this week, I would defer merging this for now. And in that case, I propose we merge the current E3SM Icepack to the Consortium, then deal with this PR later, either as part of the zaerosols/zbgc upgrade or as it's own PR to the Consortium Icepack at the appropriate time (probably after syncing Consortium back to E3SM).

[eclare108213]

I'm in favor of waiting to merge this, since we are so close to having the initial E3SM PR done. It can come in later with some of the other aero/BGC changes, or as a separate PR after the E3SM and Icepack repos are resynced.

[njeffery]

That's fine by me.

[eclare108213]

Outdated PR. These changes will be included in the BGC PR.