ESM working group: Meeting notes 2024

Earth System Working Group
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34

Date: 5/12/2024
Participants: 17
Chair: @spencerwong

  1. Opening and welcome:
  • ESM WG meetings are on pause over the summer break, and will return on February 6.
  • There are no speakers confirmed for next year’s meetings. Please consider presenting, or inviting a colleague to present. Members are encouraged to reach out to @spencerwong or any co-chair if they are interested in presenting.
  • There are no speakers confirmed for future meetings. Please consider presenting, or inviting a colleague to present. Members are encouraged to reach out to Aidan or any co-chair if they are interested in presenting.
  1. Shared Resources and Experiments:
  • ESM project lg87 has used 485 KSU of its 875 KSU allocation for this quarter. /g/data storage has grown to 43TB.
  • Dietmar Dommenget may be able to use a few hundred KSUs on low resolution ACCESS-CM2 simulations.
  • Julie Arblaster and Fraser Dennison are working on ESM1.5 meltwater simulations, which will use a couple hundred KSUs and may be ready to run in December.
  • Do you have any proposals for shared experiments? See guidelines for how to do this. There are often used resources we can access if there are projects to use them.
  1. CMIP7 Fast Track Updates:
  • @RachelLaw led a session on CMIP7 fast track updates, focusing on model development.
  • CM3/ESM3 work has focused on on ocean bathymetry, runoff mixing, melt ponds, cloud parameters, and bare soil roughness.
  • ESM1.6 development is being coordinated via weekly ocean and sea ice, and land and atmosphere standup meetings.
  • Recent technical work includes repository updates, updating Spack configurations, and running new configurations using Payu.
  • Ocean biogeochemistry updates:
    • Matt Chamberlain and Pearse Buchanan have made progress in balancing ocean carbon fluxes with WOMBAT light, and work is underway to check stability in longer runs.
  • Pseudo Iceberg Scheme:
    • Dave Bi presented on the implementation of a new pseudo iceberg scheme, which distributes runoff between coastal runoff and iceberg melt further from the coast.
    • The new scheme was found to improve Antarctic bottom water formation, ACC transport stability, and stabilises the ocean heat content partially through the inclusion of latent heat fluxes. Impacts were also seen on the Nino3.4 power spectra, and investigation will be undertaken to understand these results.
  • Land Surface Updates:
    • Rachel Law discussed sensitivities to parameter choices in the land surface model when using CABLE 3.
    • Assumptions around root distribution were found to be particularly important for carbon fluxes.
    • Updates to the root distributions were found to reduce the magnitude of the seasonal cycle, which aligns less with observations. Work will continue to determine the final parameters to use in the model.
  1. ESM1.5 Performance:
  • A recent paper highlighted that the ACCESS-ESM 1.5 model ranks very well in terms of terrestrial carbon cycle performance compared to other CMIP6 models.
  1. ESM1.5 minor release:
  • A minor release for ESM1.5 is planned to be made available before the end of the year. Changes will include runtime orbital parameters, reduced spinup output presets, reduced walltimes using an updated processor decomposition, use of the released um2nc package for netCDF conversion, and bug fixes.

Additional information