Add regularized coulomb & debris friction tests for MISMIP+ by matthewhoffman · Pull Request #938 · MPAS-Dev/compass

matthewhoffman · 2026-02-28T05:12:14Z

This PR adds new MALI tests for the new debris friction law capability and the existing regularized coulomb capability. It adds variants to the MISMIP+ smoke test for these friction laws and the existing weertman friction law. Each of three variants have separate yaml files appropriate for that friction law. The standard input file consisting of a spunup 2km state is modified for the regularized coulomb and debris friction variants to use appropriate parameters values as input fields. These are not meant to be consistent with the spunup glacier state in the file, but allow the smoke test to test each of the 3 friction laws for a reasonable glacier state. The PR also adds the RC and DF variants to the full_integration suite so that we have test coverage for those friction laws.

Checklist

User's Guide has been updated
Developer's Guide has been updated
API documentation in the Developer's Guide (api.rst) has any new or modified class, method and/or functions listed
Documentation has been built locally and changes look as expected
The MALI-Dev submodule has been updated with relevant MALI changes
Document (in a comment titled Testing in this PR) any testing that was used to verify the changes
New tests have been added to a test suite

Also add it to the full integration suite

* shorten smoke test length * add fallback for core_per_node

Refactor smoke_test and run_model for MISMIP+ case to support 3 variants: weertman, regularized coulomb, debris friction Each has a different yaml file, which is selected based on the variant.

mperego · 2026-03-03T14:51:26Z

compass/landice/tests/mismipplus/albany_input_debrisfriction.yaml

+  #   Side Set Discretizations:
+  #     basalside:
+  #       Exodus Output File Name: albany_output_basal.exo
+


Do we need to set a uniform Flow Rate, or the default one based on the temperature is correct?

The spinup uses this uniform flow rate, it's one of the parameters set as a constant for the intercomparison project

Are the flow rate lines supposed to be in their own section LandIce Viscosity , or is it okay to set them there under Basal Friction Coefficient?

Are the flow rate lines supposed to be in their own section LandIce Viscosity , or is it okay to set them there under Basal Friction Coefficient?

The flow-rate lines in the Basal Friction Coefficient section are only used for the boundary condition. If they are not specified in the Basal Friction Coefficient section, they are inferred from the ones in the LandIce Viscosity.

mperego

Looks good to me.

mperego · 2026-03-03T15:02:56Z

compass/landice/tests/mismipplus/albany_input_regularized_coulomb.yaml

+          Mu Type: Field
+          Power Exponent: 0.3333333333
+          Effective Pressure Type: Hydrostatic Computed at Nodes
+          Zero Beta On Floating Ice: true


Zero Beta On Floating Ice: true
This is no longer needed. It's on if glp is enabled. It goes to zero anyway on nodes on floating ice.

jeremy-brooks-1 · 2026-03-03T17:35:50Z

compass/landice/tests/mismipplus/run_model.py

+
+        with xr.open_dataset(mesh_filename) as ds_mesh:
+            ds_mesh['muFriction'].loc[:] = 0.4
+            ds_mesh['bedRoughnessBC'] = xr.full_like(ds_mesh['muFriction'],


I think this should be bedRoughnessRC.
I also think the value here for bedRoughnessRC should be multiplied by 1000. If I recall correctly, when the value is set in the mesh, we use MPAS units (m^-1). But if it's set in the albany_input.yaml file, we use Albany units (km^-1). Is that correct? I checked LandIce_BasalFrictionCoefficient_Def.hpp and Interface.cpp but didn't see any scaling applied...

bed roughness in is [m] in MPAS / netcdf grid, and in [km] in Albany / exodus grid.
The conversion happens in the Interface_velocity_solver.cpp file

jeremy-brooks-1 · 2026-03-03T17:36:20Z

compass/landice/tests/mismipplus/run_model.py

+
+        with xr.open_dataset(mesh_filename) as ds_mesh:
+            ds_mesh['muFriction'].loc[:] = 0.4
+            ds_mesh['bedRoughnessBC'] = xr.full_like(ds_mesh['muFriction'],


I think this should be bedRoughnessRC.

Good catch!

jeremy-brooks-1 · 2026-03-03T17:40:47Z

compass/landice/tests/mismipplus/run_model.py

+            ds_mesh['bedRoughnessBC'] = xr.full_like(ds_mesh['muFriction'],
+                                                     6000.0)
+            ds_mesh['basalDebrisFactor'] = xr.where(
+                ds_mesh['xCell'] < 200000.0, 3.2e-2, 0.0)


We may as well add bulkFriction coefficient for testing too?

ds_mesh['bulkFriction'] = xr.where( ds_mesh['xCell'] < 400000.0, 0.005, 0.0)

@jeremy-brooks-1 , is the x value where this changes meant to be different than that for basaDebrisFactor?

matthewhoffman · 2026-03-04T03:46:13Z

Testing

I ran the 3 variants of the smoke test and got reasonable results for the velocity solution at the initial time for all 3. This was run on the Docker container on my Mac m1 (but compiled for amd64) and run with 10 tasks.

Weertman

  test execution:      SUCCESS
  test validation:     PASS
  test runtime:        01:50

Regularized Coulomb

  test execution:      SUCCESS
  test validation:     PASS
  test runtime:        00:48

Debris Friction

  test execution:      SUCCESS
  test validation:     PASS
  test runtime:        00:53

matthewhoffman · 2026-03-04T03:59:31Z

Update: this appears ready to merge, barring any further adjustments from @mperego and @jeremy-brooks-1 . But we will wait to merge until the MALI-Dev/E3SM PR is merged and the submodule can be updated.

matthewhoffman added 3 commits February 27, 2026 20:49

Add landice/mismipplus/smoke_test/2000m to full_integration

56a6510

Add debris friction variant of mismip+

68223f2

Also add it to the full integration suite

mismip+ updates

261abd9

* shorten smoke test length * add fallback for core_per_node

matthewhoffman requested review from mperego and trhille February 28, 2026 05:12

matthewhoffman added land ice in progress This PR is not ready for review or merging labels Feb 28, 2026

jeremy-brooks-1 mentioned this pull request Mar 3, 2026

Add debris-bed friction slip law MALI-Dev/E3SM#135

Open

matthewhoffman added 4 commits March 2, 2026 19:47

Support 3 friction laws for MISMIP+

a789e19

Refactor smoke_test and run_model for MISMIP+ case to support 3 variants: weertman, regularized coulomb, debris friction Each has a different yaml file, which is selected based on the variant.

Update docs and full_integration suite

b4e4627

Only update frictions field for smoketest

515d4f9

update api docs

dd14cd3

matthewhoffman changed the title ~~Add debris friction test with MISMIP+~~ Add regularized coulomb & debris friction tests for MISMIP+ Mar 3, 2026

Cleanup

2d041e8

matthewhoffman force-pushed the landice/mismipplus-debrisfriction branch from 8e98237 to 2d041e8 Compare March 3, 2026 04:26

mperego reviewed Mar 3, 2026

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mperego approved these changes Mar 3, 2026

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mperego reviewed Mar 3, 2026

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jeremy-brooks-1 reviewed Mar 3, 2026

View reviewed changes

Updates from code review

3f4b38b

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matthewhoffman commented Mar 4, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Testing

Weertman

Regularized Coulomb

Debris Friction

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matthewhoffman commented Mar 4, 2026

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matthewhoffman commented Feb 28, 2026 •

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