COSIMA TWG Meeting Minutes 2025

COSIMA TWG
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TWG meeting - 29 Jan

Attendees: @micael, @CharlesTurner, @helen, @anton, @cbull, @aekiss, @Minghangli, @Martindix, @dougiesquire

Agenda can be found in this link COSIMA TWG Announce - #55 by aekiss.

  1. ACCESS-NRI COSIMA training program and upcoming cosima ‘main’ training session - @CharlesTurner

For the Cosima meeting:

  • @minghangli will present a 5 minute overview of the parameter manager tool and reference his training session in May.
  • A 20-30 minute talk on new Payu features will be delivered by @anton, @Aidan, or @jo-basevi.

Training program outpline:

  • create users’ own datastore
  • some basics using intake
  • Q&A
  • searchable coordinates for the ocean files (current issues where grid-related searches are not indexed by Intake).

@CharlesTurner has almost finished the cli for making intake datastores. He’s currently writing the tests. He’s also working on the coordniate search within intake ESM, allowing catalog to support searchable coordinates.

For the training program, it is good to have breakout rooms to allow people to retain knowledge better and allow informal discussion. There may also people jump in to ask other questions related to intake, it is better to leave some time for that as well.

@CharlesTurner is also working on the model autodetection through CLI when buidling a catalog. @dougiesquire raised concerns about validation risks, as model names are not strictly prescribed.

  1. Choice of compiler for ACCESS-OM3, moving to ifx - @micael
  • IFX provides better optimisation for Sapphire Rapids compared to classic Intel compilers.
  • For spack builds, when the release team has made available configuration to use IFX on Gadi, it is easy to make a switch by simply changing the name of the compiler used in the spack environment.
  • @MartinDix has tested UM with IFX a while ago and the performance is pretty much the same as with IFORT, and is considering moving CM3 to IFX.
  • All model components need to be compiled with IFX due to Fortran module compatibility constraints.
  1. OM3 0.25deg project board
    3.1 0.25deg ocean mask error

  • @MartinDix found differences on the tripolar edge between @aekiss and @ezhilsabareesh8 versions. @aekiss suggested waiting for @ezhilsabareesh8to return for further discussion.

    3.2 diag_table

  • Discussions on diag_table daily / monthly output frequency and potential performance concerns when switching to daily output.

  • Ongoing discussions on managing diag_table and diag_table_source.yaml, where the yaml configuration file along with GitHub - COSIMA/make_diag_table: Python script to generate MOM diag_table is used to generate the diag_table. An issue is created Diagnostic table files management · Issue #259 · COSIMA/access-om3 · GitHub, where there will be further discussions there.

    3.3 KPP and epbl with fixed runoff

  • @minghangli analysed salinity comparisons at the Amazon river mouth over time and across z* coordinates. Results show similar trends with KPP. The rivermixdepth parameter (40m or 20m) has minimal impact. Seasonal cycles are stronger, but salinity remains low (~0.02 PSU).

  • epbl with/without fixed runoff has velocity truncation errors, but KPP does not. Before the runoff fix, truncation errors appeared around Antarctica. Since runoff is a constant in time, errors may be circulation-related. @minghangli will provide a spatial plot of the new truncation errors with runoff fix. One thing to note, before runoff fix, truncations happened in a row of 10 years and seemed persistent.

  • @MartinDix mentioend that Kieran has been testing the horizontal spreading without epbl.

Next TWG is assigned: Chair: Dougie. Minutes: Andrew K. Andrew will give summary of this TWG at next COSIMA meeting.

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