COSIMA TWG Meeting Minutes 2025

Date: 25 Jun 2025
Chair: @cbull
Minutes keeper: @anton
Attendees: @dougiesquire @helen @sofarrell @ezhilsabareesh8

Minutes

Sub-mesoscale parameterisation

See [Parameter Testing] Sub-mesoscale parameterisation · Issue #435 · ACCESS-NRI/access-om3-configs · GitHub

AS showed some results from turning on a sub-mesoscale paramaterisations, showing low salinity in Arctic.

Its hard to say if low salinity is the confirmed cause of the sea-ice thermodynamics issue, but seems likely.

Suggestions to check:

  • is bathymetry shallow
  • how does model surface salinity compare to WOA23
  • check runoff volume at location
  • investigate turning off MASK_SRESTORE_UNDER_ICE
  • could use mushy rather than BL99 sea ice thermodynamics for better handling of v. low salinity
  • global SST plot compared to the baseline run for overall impact of changing parameterisation

SST bias:

@aekiss identified the SST biases in OM3 25km config seem higher and sometimes different sign than the OM2-025 biases. Needs investigation and longer run.

DATM/DROF time interpolation

AS showed Fix/check time in data atm/rof stream files · Issue #437 · ACCESS-NRI/access-om3-configs · GitHub

  • agreed to linear interpolate runoff and raise an issue to implement an improved runoff scheme

rho coordinate in ocean

Deferred discusson until AH is available. Dougie to organise a meeting.

Compute

Quarter ends monday night - looks like its ok

ESM1.6

@ezhilsabareesh8 has updated mediteranean sea bathymetry - deepened sicily straight. There is some impact, but not enough yet. We probably need to try doing a test run with some widening of the straits but also compare model results to observations if possible.

SoF will have a look at the output from CICE5 runs as well. DB might be on leave this week.