Feb 7th /2025 minutes
Present: @cbull @Wilton_Aguiar @claireyung @fabiobdias @adele157 @helen @aekiss @angus-g @AndyHoggANU
Not present: @ezhilsabareesh8
Four main topics were discussed in this last meeting. Here is a summary of them.
Pole displacement:
-Claire is working on displacing the grid’s South Pole and extending the grid using the ocean_model_grid_generator
- Issue: One issue has been avoiding discontinuities in dx, dy, and aspect ratio when displacing the pole. With the currently generated grid, it seems that there are discontinuities in dy and aspect ratio in the Ross and Weddell Seas, while the borders of the displaced pole over land don’t have the same issue.
- Next steps: We decided to move on and just use an extended grid with no South Pole displacement. If numerical instabilities arise, it might be worth trying to refine the Weddell/Ross dy to solve the discontinuity issue in away that allows the South Pole displacement to significantly increase grounding line grid size.
Ice shelf thickness product to use:
- Issue: Currently we are using GEBCO2024, which contains the old BedMachine v2 for ice thickness.
- Two new ice thickness products could be used instead: BedMachine v3, and AntGG2021. It would be nice to use these newer products, however they are not stitched into the GEBCO bathymetry. That means using the latest products would require us to reproduce the stitching method used in GEBCO2024.
- Next steps: Evaluate if the newer products represent a significant improvement relative to GEBCO2024/BedMachine v2. Also, contact the GEBCO group to see if they are working on releasing a new product that incorporates BedMachine v3: this would allow us to eliminate the effort of reproducing their stitching method.
Initial conditions interpolation:
- Issue 1: There is some leakage of the TS properties from Amundsen to the Weddell sea.
- Issue 2: Currently, we use offshore WOA data to interpolate the data into the ice shelf cavities. This offshore data is likely too warm and could create spurious melting if used as initial conditions.
- Steps to solve issue 1: Play around with the current interpolation tools, and try to figure out a way method that properly separates the Amundsen and Weddell shelves. @Wilton_Aguiar 's task
- Steps to solve issue 2: Test other observational products containing data closer to the ice shelf, such as Schmidko, Pauthenet and Kaihe’s Climatology.
Vertical coordinate choice:
- Currently, we are debating between using SIGMA_SHELF_ZSTAR and ZSTAR.
- Issue: SIGMA_SHELF_ZSTAR have strong discontinuities along the ice shelf front. ZSTAR don’t have these discontinuities, but it doesn’t continuously represent the ice shelf ocean boundary layer. A more ideal coordinate would combine the best parts of each, but requires mapping where the ice shelf caving front is.
- Steps to solve: Being debated on GH
I probably missed a lot here, so please edit to add any missing info.