# COSIMA TWG Meeting Minutes 2024 **URL:** \ **Category:** TWG\ **Tags:** meeting, twg, notes, minutes\ **Created:** [17 January 2024 05:11 UTC](https://forum.access-hive.org.au/t/cosima-twg-meeting-minutes-2024/1734 "2024-01-17T05:11:58Z")\ **Posts on this page:** 1\ **Showing post:** 12
**Author:** ![minghangli](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/minghangli/32/1699_2.png) [@minghangli](https://forum.access-hive.org.au/u/minghangli)\ **Post date:** [17 July 2024 23:46 UTC](https://forum.access-hive.org.au/t/cosima-twg-meeting-minutes-2024/1734/12 "2024-07-17T23:46:41Z")
Summary of today’s TWG - I didn’t catch everything so please edit to add/correct as needed. Date: 2024-07-17 **Attendees:** - Adele Morrison (AM)@adele-morrison - Andy Hogg (AHogg) @AndyHoggANU - Andrew Kiss (AK) @aekiss - Angus Gibson (AG) @angus-g - Anton Steketee (AS) @anton - Ezhil Kannadasan (EK) @ezhilsabareesh8 - Dougie Squire (DS) @dougiesquire - Kieren Ricardo (KR) @kieranricardo - Minghang Li (ML) @minghangli - Paul Spence (PS) @PSpence - Siobhan O’Farrell (S0) @sofarrell DS: - Model runs with working group on Gadi - The `ZV30` project, which is for CMIP7 evaluation, is the right place for data storage, including WOMBAT runs and 0.25deg OM3 testings that ML set up. Currently there is only around 6GB out of a total of 50TB allocated to the `ZV30` project, which includes both 0.25-deg OM3 and WOMBAT relevant to CMIP7. - AM: No instructions were provided regarding the usage of `OL01` storage. There might be a chance to request additional storage if it is used up. KR: - CICE cap initially runs at the same timestep as the coupling timestep. Now, it can run multiple steps per coupling timestep, but currently has the averaging issues. - Energy conservation is reasonable, but the ice fractions appear strange, possibly due to improper averaging of ice fluxes before sending them to the ocean. - Averaging occurs in the cap before sending data across, rather than in the mediator. - DS: Changes have been made to a ~6 month old fork of CICE, well need to harmonise at some point. - AS: Current OM3 - CICE version is between 6.5 and 6.5.1, with no significant scientific changes but infrastructure improvements. DS: - Default parameters - Every year, MOM developers review and decide on changes to default parameter. And there are a bunch of parameters to change. Our approach of removing default parameters from `MOM_input` could be risky. Some parameters we rely on as defaults may change without our awareness, potentially causing unexpected results. This is another reason to [automatically generate `MOM_parameter_doc.*`](https://github.com/COSIMA/access-om3/issues/117) and track them with git so we can detect changes. ML: - Created a preliminary list of parameter changes and identified several scientific tests to start: - Starting with tracer timestep tests as they significantly improve performance. No specific preference for other parameters; all will be tested. - Comments from Attendees: - Hybrid coordinates - Parameter change process/protocols AK: - CMIP7 deliverables - working underway on optimising OM3 at 1deg and 0.25deg - working underway on tune parameter testings on 1deg and 0.25deg - working underway on testing 1deg and 0.25deg with WOMBAT-lite - need to determine the speed before testing 1-degree and 0.25-degree models with WOMBAT-mid. - DS: WOMBAT-mid is still under development. - SO: For the 0.25deg, it will be very expensive with BGC because we have to do pre-industrial controls, pre-emission controls and etc. - consider performing offline BGC runs to accelerate parameter tests and spinup. Unclear how much development would be needed for offline BGC - should scope it out before committing, but would be great to have if not infeasibly difficult. EK - Grid update - We are now able to generate a grid that closely matches the OM2 grid. - Changes we want to make in the new grid (copied from [New grids · Issue #172 · COSIMA/access-om3 · GitHub](https://github.com/COSIMA/access-om3/issues/172#issuecomment-2232235022)) - 1. leave tripole points where they are - 1. leave longitudinal seam as-is - 1. **explore putting C-grid zonal points exactly on the equator** - 1. don’t extend 1° or 0.25° closer to the pole, since they won’t have ice cavities, but **extend to grounding line to support ice cavities at 0.1° and higher, using a displaced pole** (this can be done with [ocean\_grid\_generator.py](https://github.com/nikizadehgfdl/grid_generation/blob/dev/ocean_grid_generator.py) but can wait until after we’ve handed over 1° and 0.25° OM3 configs for CMIP7) - 1. **Refine in the Antarctic by extending the Mercator region to 75°S and then extending with constant `dx` to the southern edge of the grid.** No coarsening in the Arctic. - 1. **Quantize double-precision to be exactly representable in single precision** - 1. **use [GEBCO2023](https://github.com/COSIMA/access-om3/issues/68#issuecomment-2125996992) topography** - 1. **make sure grid allows MOM6 output at half-resolution** --- _[View the full topic](https://forum.access-hive.org.au/t/cosima-twg-meeting-minutes-2024/1734)._