[hyungyukang]

This PR fixes a bug in the vertical range used when initializing and splitting the baroclinic velocity, which caused an incorrect Coriolis acceleration calculation over non-flat bottom topography when the Coriolis parameter varies spatially.

Checklist

• Linting

  • Pre-commit run locally

• Building

  • CMake build does not produce any new warnings from changes in this PR

• Testing

  aurora, oneapi-ifx, mpich

  • CTests Pass
  • Polaris omega_pr Pass

  chrysalis, oneapi-ifx, openmpi

  • CTests Pass
  • Polaris omega_pr Pass

  frontier, craygnu, mpich

  • CTests Pass
  • Polaris omega_pr Pass

  frontier, craygnu-mphipcc, mpich

  • CTests Pass
  • Polaris omega_pr Pass

  pm-cpu, gnu, mpich

  • CTests Pass
  • Polaris omega_pr Pass

  pm-gpu, gnugpu, mpich

  • CTests Pass
  • Polaris omega_pr Pass

• Provide relevant details in a comment to the PR titled Testing with the following:

  • Which machines CTest unit tests
    have been run on and indicate that are all passing.
  • The Polaris omega_pr test suite
    has passed, using the Polaris e3sm_submodules/Omega baseline
  • Document machine(s), compiler(s), and the build path(s) used for -p for both the baseline (Polaris e3sm_submodules/Omega) and the PR build
  • Indicate "All tests passed" or document failing tests
  • Document testing used to verify the changes including any tests that are added/modified/impacted.

[hyungyukang]

Since this PR uses the split-explicit time stepper, I tested the omega_pr suite using this Polaris PR.

Polaris omega_pr suite

• PR build: /lustre/orion/cli115/proj-shared/hgkang/E3SM/OMEGA/Polaris/work/pr_suite/260916_se_fix/baseline_omega/build
• PR workdir: /lustre/orion/cli115/proj-shared/hgkang/E3SM/OMEGA/Polaris/work/pr_suite/260916_se_fix/baseline_omega
• Machine: frontier
• Partition: batch
• Compiler: craygnu-mphipcc
• Build type: Release
• Log: /lustre/orion/cli115/proj-shared/hgkang/E3SM/OMEGA/Polaris/work/pr_suite/260916_se_fix/baseline_omega/polaris_omega_pr.o5495312
• Result: All tests passed

[hyungyukang]

I ran two test cases: the SOMA test on the 32 km mesh and the realistic global ocean test on the EC30to60E2r2 mesh.

Since these tests require KPP mixing for better results, I rebased this PR branch onto #512.
The baroclinic and barotropic time step sizes are 30 minutes and 1 minute, respectively.

• Surface kinetic energy at day 200 from the SOMA test on the 32-km mesh
  • The MPAS-O result is from @mark-petersen’s test in this comment.
  • Compared with the Omega split-explicit (SE) results before the bug fix, the results from this PR are much closer to those from Omega RK4 and MPAS-O SE.

• Surface kinetic energy at 3 months from the realistic global ocean test
  • The overall behavior is consistent with the SOMA test case. The results are now closer to the Omega RK4 and MPAS-O SE results, and some spurious high KE at higher latitudes that appeared before the bug fix disappears after the fix.

[hyungyukang]

@mark-petersen , Since you’ve been testing the split-explicit time stepper, could you please review this PR when you have a chance?

[mark-petersen]

Wonderful! Yes, that is exactly the fix we were looking for! Approved based on visual inspection and testing by @hyungyukang above.