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0.25deg configuration #101
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Some tasks for the initial prototype:
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This issue has been mentioned on ACCESS Hive Community Forum. There might be relevant details there: https://forum.access-hive.org.au/t/cosima-twg-meeting-minutes-2024/1734/3 |
The initial run of the quarter-degree configuration using the latest access-om2 grids and input files from The ESMF mesh file was created using 0.25-degree access-om2 ocean hgrid and topog files via the Below is the specific error message encountered during the run:
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Weird - this is the same code that Dougie had an issue with in the 1 degree config and put the patch in for: https://github.com/COSIMA/access-om3/blob/main/CICE/patches/ice_mesh_mod.F90.patch It looks like all the lons are offset by 0.25 degree, suggesting maybe a missing first/last column? You maybe could set 'eps_imesh' to a big value and compare the grid from the cice output to the mesh file / hgrid file to debug this? |
It appears that the issue lies beyond the section of code in To proceed, I decided to suppress the check, allowing the code to run. However, I've encountered a new problem in the mediator. NaNs are being detected in the calculation of |
Hi Ezhil It looks like the CICE grid for 1 degree goes from -279 to 80 but for 0.25 degree goes from -280 to 79.75
Returns:
Returns: Presumably the first one is correct (and would be consistent with u points / b-grid), and we need to shift the 0.25 degree grid to the right by 0.25 deg, but maybe @aekiss can confirm? |
Ezhil pointed out that the mesh check is cheching tlon from CICE to the ESMF mesh file and my results above are from ulon. Tlon field is correct in both 1deg and 0.25deg CICE grid files, but CICE is not using tlon from the grid file and is instead interpolating it (https://github.com/CICE-Consortium/CICE/blob/9e9e5b3fabd88c429c4632baa8235187129e2dd7/cicecore/cicedyn/infrastructure/ice_grid.F90#L952). |
It looks like there's an error in the OM2 0.25° grid - the u points are in the NW corner of cells instead of the NE corner. I'm investigating. |
Are the current checks in the cmeps caps sufficient for OM3? It looks like both MOM and CICE caps have checks to compare between the component grid and the ESMF mesh file. Although the CICE allowed tolerance is 0.1, which we should probably configure to something stricter (MOM is 1e-4)? They don't use all the variables in the model grid files however, so that could be a point of inconsistency. |
A tolerance of 0.1° is far too coarse to be useful at high resolution - it would be good to use something finer, eg 1e-4. It would be good to have a consistency check between all variables in the mom6 and cice6 grids somehow. |
And the other question then is are we checking just the input grids or also the output files? |
Checking inputs is more important. Since they should be identical at double precision (unlike our current 1deg grids), maybe our tolerance should be (say) 1e-7° instead of 1e-4°. However, this would break our current 1° config so we may need to wait until we update our grids before applying this at 1°. |
Thanks @anton-seaice and @aekiss. Resolved longitude mismatch error by generating the CICE grid from the MOM super grid. U points are now positioned in the NE corner. Updated CICE grid:
The script written to generate the CICE grid from the MOM super grid has been uploaded to |
Thanks @ezhilsabareesh8, can you make a PR for this? I have some suggestions that would be easier to make that way. |
Thanks to @dougiesquire's suggestion, I resolved the NaN issue by updating |
Awesome! |
Has it been possible to run the 0.25° config for longer than 5 steps? |
The configuration fails after 45 days, encountering an error related to bad departure points in CICE. The error message displayed is:
The departure points are going out of bounds, specifically more than one grid cell away. Here is the relevant code:
I think it is due to CFL condition violation and I attempted changing the coupler time step (I believe it is same as the thermodynamic time step of CICE) from 3600 seconds to 1800 seconds. However, I continue to face the same problem, any thoughts @aekiss. I have updated the quarter degree configuration in this branch, and I believe the restart file issue is related to Payu providing incorrect restart file names (refer to this issue). I suspect it could be related to the modules I am loading. It would be of great help if @minghangli-uni or @anton-seaice could check the quarter-degree configuration and see if they can reproduce the restart file issue. |
My run survived until 94 days with dt=900s and dttherm=3600s. Like @ezhilsabareesh8, the reason for failure was Instead of the MOM_input parameters provided in 1deg_jra55do_ryf, I have updated another configuration using ePBL instead of KPP for the surface boundary layer parameterisation. Will upload it soon. For the restart file issues, I dont have any for 1deg but do for 0.25deg.
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Yes, "bad departure points" is a CFL error, so you may need to reduce the timestep further. Specifically, you need to reduce the dynamic timestep, which is a fixed fraction of the thermo timestep. The parameter controlling the ratio is |
ACCESS-OM2-025 was able to run consistently with dt=1350 for both cice thermo and dynamics (see timestep column here) so I'm surprised this isn't more stable. What's the cice initial condition? From the input files #124 (comment) it seems it's not starting from an access-om2 initial condition at 0.25deg like we did at 1deg? see #50 |
We are currently testing the
Will conduct the test in a manner similar to 1deg. |
@ezhilsabareesh8 . I believe in your configuration, The vgrid conversion process should follow a similar approach to the following step:
@aekiss any thoughts? A reminder of our last namelist discussion, we aimed to set
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I am running an experiment with I tried initial runs with |
It is same as OM2 025 deg configuration's
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What does the ice output look like? See #50 (comment) |
@minghangli-uni note that When we make the switch to 75 levels for 1° and 0.25° we should just re-use |
Note this should be fixed by payu-org/payu#432 |
Thank you all for your inputs and suggestions. I have fixed the bad departure points error by changing the time step to I am able to run this configuration for two years without encountering any errors, please refer to this PR. |
@aekiss, this is true for MOM5, but not for our MOM6 configs. @minghangli-uni is correct that :history = "Fri Jul 28 09:29:32 2023: ncks -O -d nzv,,,2 /g/data/ik11/inputs/access-om2/input_20201102/mom_1deg/ocean_vgrid.nc ocean_vgrid.nc\n | Updated on Thu Oct 15 17:49:39 AEDT 2020 using https://github.com/COSIMA/make_1deg_topo/tree/db7b546" ; So the same thing needs to be done for the OM2 0.25deg |
Thanks @dougiesquire and @minghangli-uni. I have updated 025deg's
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A priority for CMIP7 is to have a working 0.25° MOM6-CICE6 configuration.
I think the first step should be a working RYF configuration based on
1deg_jra55do_ryf
but with 0.25° inputs and parameter modifications based on ACCESS-OM2, in order to quickly produce an initial prototype for use in ACCESS-CM3-025 development and for scaling performance tests.At some point later we can develop IAF configs and also RYF and IAF for MOM6-CICE6-WW3.
After we switch to c-grid cice we can update topography to exploit c-grid and also take the opportunity to extend the grid further south.
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