COSIMA TWG Meeting Minutes 2024

COSIMA TWG
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Here’s my attempt to summarise today’s TWG. Didn’t capture everything, so please add and correct as needed.

Date: 2024-06-05

Attendees:

DS:

  • attended MOM6 dev meeting

    • good that we now have a formal connection
    • Work is proceeding in multiple centres that we should be more closely paying attention to
    • much discussion on BGC
      • NCAR MARBL BGC model
        • ocean model agnostic
        • have been working on getting it working with MOM6
        • needed changes to NUOPC cap and a number of other places in MOM6 src
        • Mike Levy is leading this
        • PR imminent
        • changes overlap somewhat with Dougie’s generic tracer changes
        • they’ve had similar issues in handling BGC in vanishing layers, e.g. remineralising from sediment into vanished layer
    • COBALT - new project to overhaul to get COBALT v3 - still a generic tracer but will need MOM6 stuff to compile - so may need to include MOM6 code to run in MOM5
    • Angus told Bob we’re ready to become a MOM6 node
      • they’re happy for that to happen
      • they’re interested in tests with regional model - hopefully will happen once we have regression testing set up
      • we’re just waiting on a PR from release team to get testing working
      • AG - email from Marshall outlining process in getting on the MOM6 review team
    • Discussion of sinking schemes (cc @pearseb) - MOM6 sinking scheme is simple - only sink at a single rate - would like spatially variable sinking - generic tracer sinking is handled separately but still constant rate unless you implement yourself when updating sources.

Generic tracer wombat

  • running in OM3
  • trying to get running in ESM1.6
  • now running generic in ACCESS-OM2
  • a few differences, unclear if they are worrisome, will post on forum for feedback - main difference is detritus
  • Dougie must have misunderstood earlier conversation about WOMBAT virtual fluxes. Need to do virtual flux corrections to surface bgc fluxes to account for using salt restoring. Awkward because not possible without extending the generic tracer API to pass salt flux. Apparently not done in BLING, COBALT etc?

Using OM2 spack dev tools - mostly works well, some annoyances

We are nearly at the point of doing science parameter test runs with 0.25° ACCESS-OM3 config

ACCESS-OM2 BGC releases aren’t restart-reproducible (2x1day differs from 1x2day run) - only BGC tracers differ.

  • WOMBAT restarts - 2 files, one is for most tracers, the other for sediments, handled in different code sections - might be what is breaking repro?
  • Problem might go away when we use generic tracers for WOMBAT in ACCESS-OM2?

OM2 release plans