COSIMA TWG Meeting Minutes 2026

Date: 11 Feb 2026

Attendees: @sofarrell, @AndyHoggANU, @aekiss, @kieranricardo, @anton, @dougiesquire, @Paul.Gregory
Chair: @cbull
Minutes: @minghangli

1. Data comparison and early evaluations

  • @AndyHoggANU aims to compare OM3, CM3, OM2 at 8km and 25km using available data in the datastore.
  • @kieranricardo suggested salinity and wind stress look improved after a fix (reference for this fix??). Adding iceberg flux increased sea ice, which is helpful in some regions but may worsen already-high northern hemisphere total sea ice and it is too high. Ice now appears around Greenland.
  • Some concerns are deferred until the B-grid landmask is available. Until then, avoid overinterpreting artefacts.

2. B grid landmask + topography workflow

  • @aekiss reported polar B-grid landmask/topography workflow is basically done but not fully tested.
  • Updated topo and mask files have been generated and staged in pre-release but not pushed to configs yet because further checks are still pending, such as restoring, marginal seas and other tweaks.
  • Changes are focused on coastal/marginal sea regions where any sea ice has occurred in long runs.
  • We agreed to finish validation test first then push to the iaf configs and likely run a new iaf cycle incorporating fixes. Start a fresh CM3 run once the new landmask is minimally tested.

3. MOM6 dev meeting updates

  • @dougiesquire made notes in #ocean-seaice > MOM6 dev calls @ :speech_balloon: and the update highlighted MOM6 move towards Apache 2.0 relicensing - all contributors have approved. This mainly makes code share into/out of MOM6 easier across models.
  • @dougiesquire showed what we do with Zenodo releases. Bob and Alistair seemed to like the approach.
  • @angus-g is expected to submit an adaptive grid PR at some stage (not urgent, paper is still needed)

4. 100km grid generation

  • @ezhilsabareesh8 raised questions on the ocean_model_grid_generator with the equitorial refinement. It produced sharp transitions and a completely different profile even though it fixed a north pole area spike and some bifold issues.
  • On the other hand, make_hgrid can reproduce what access-om2 used but introduces a tiny bifold asymmetry due to a rotate-pole area calculation (difference is very small).
  • We agreed the symmetry artefact is not a concern and it’s better to use the tool that produces the right functional form and overall behaviour.
  • One tweak is requested to move the start of the constant Y southern band from 78S to 75S to add a bit more resolution at those latitudes.

5. Render evalution figures

  • @cbull provide a quick figure first view for community members who want to contribute scientifically without running code.
  • @anton preferred hosting in the same repo as the recipes/notebooks and publish versions via tags so each tag builds a version of the site. This avoids PR overhead.
  • Some concerns:
    • Maintenance burden is the biggest risk - notebooks dont run out of the box and checking results is time-consuming.
    • Some clarity needed on if figures are snapshots or averages and what time windows were used.
    • Fully rendering notebooks is simpler but can be long. Summary pages are more usable but introduce extra curation steps.
  • It’s better to write down exact steps so effort can be compared directly.
  • Decide how to embed or standardise metadata such as averaging period or snapshot timing without relying on people membering to manually edit captions.

6. TWG reporting

  • @aekiss proposed replacing purely minute-based reporting with a short curated highlights update aimed at what the community actually cares about.
  • Keep minute-taking process the same but reporting can be owned by one person but open to contributions.
  • @aekiss will draft/drive the curated reporting approach and coordinate with the roster/minute-taker.

7. Next OM3 release status

  • There was concern that OM3 release work is already partially in progress but risks becoming stale due to upstream churn and @cbull has prioritised other work including Ocean Sciences travel with an approximate return around mid March.
  • The long gaps make the process harder because contexct is forgotten and upstream changes accumulate and we preferred smaller and more regular progress.
  • @anton suggested near-term risk reduction step is restart comparison or coupling sanity checks to catch obvious breakages like fields becoming zero. @cbull considers handing off parts of the release effort if not progressed before travel.