Realistic lfric2lfric configs

[cjohnson-pi]

PR Summary

• C896 to Melbourne
• C896 to UKV
• C224 to Melbourne

Also clearing the global mesh (which releases more memory for larger jobs such as these).

Tested by creating a test_branch, merging on the branch from #655, applying upgrade macro, merging on this branch and then running the lfric2lfric_ex1a_weekly group

Sci/Tech Reviewer: Juan Manuel Castillo Sanchez (@ukmo-juan-castillo)
Code Reviewer: mo-lucy-gordon

blocked by #655
split from #530
#440

Code Quality Checklist

• I have performed a self-review of my own code
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Testing

• I have tested this change locally, using the LFRic Apps rose-stem suite
• If any tests fail (rose-stem or CI) the reason is understood and acceptable (e.g. kgo changes)
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trac.log

Test Suite Results - lfric_apps - realistic/run16

Suite Information

Item	Value
Suite Name	realistic/run16
Suite User	christine.johnson
Workflow Start	2026-07-24T11:10:56
Groups Run	suite_default

Dependency	Reference	Main Like
casim	MetOffice/casim@2026.07.1	True
jules	MetOffice/jules@2026.07.1	True
lfric_apps	cjohnson-pi/lfric_apps@test_realistic	False
lfric_core	MetOffice/lfric_core@2026.07.1	True
moci	MetOffice/moci@2026.07.1	True
SimSys_Scripts	MetOffice/SimSys_Scripts@2026.07.1	True
socrates	MetOffice/socrates@2026.07.1	True
socrates-spectral	MetOffice/socrates-spectral@2026.07.1	True
ukca	MetOffice/ukca@2026.07.1	True

Task Information

✅ succeeded tasks - 1208

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Code Review

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[Juan Manuel Castillo Sanchez (ukmo-juan-castillo)]

I guess this line is here because the global mesh is not needed by lfric2lfric. Why is it not the case when the source and destination meshes are read from the same file? Shouldn't be this line outside the if sentence?

A comment in the PR indicating that this change is taking place, apart from the addition of the new tests, would be useful.

I could not find an associated issue where the details of the PR are discussed, although I know this is part of larger work.

[cjohnson-pi]

Issue is #440 - now also added above.

[cjohnson-pi]

I've adjusted the code to also clear the global mesh for the case when the source and destination mesh are from the same file.

[Juan Manuel Castillo Sanchez (ukmo-juan-castillo)]

What I meant is that the clear global mesh could be done outside the
if (mesh_file(dst) == mesh_file(src)) then
condition, but it is also possible to do it like you did.

[cjohnson-pi]

Thanks Juan. Sorry I didn't explain this. Yes I did consider putting the clear_global_mesh outside the if as you had suggested. But the reason I didn't is that when the dst is not the same as src, 2 clear_global_meshes are required - one after each create_local_mesh. So it seemed a better code structure to me to add the clear_global_mesh immediately after the create_local_mesh or create_local_maps. i.e. read global, create local_from_global, clear global. Repeat.

[github-actions]

⚠️ Hello cjohnson-pi!

Your CLA signature was found on the base branch, but you appear to have modified the CONTRIBUTORS.md file in this PR.

Please do not edit the CONTRIBUTORS.md file. If you have already signed the CLA, revert changes to the file and your signature will be picked up.

[Juan Manuel Castillo Sanchez (ukmo-juan-castillo)]

Approved, although the last comment should be considered.

[mo-lucy-gordon]

I'm happy with this code but I think another macro upgrade is needed for this PR as well, once 655 has gone on and this can be tested separately.