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
• My code follows the project's style guidelines
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• My changes generate no new warnings
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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/run18

Suite Information

Item	Value
Suite Name	realistic/run18
Suite User	christine.johnson
Workflow Start	2026-09-07T13:15:37
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@realistic	False
lfric_core	MetOffice/lfric_core@3e965e8	True
moci	MetOffice/moci@2026.07.1	True
SimSys_Scripts	MetOffice/SimSys_Scripts@77a5166	True
socrates	MetOffice/socrates@2026.07.1	True
socrates-spectral	MetOffice/socrates-spectral@2026.07.1	True
ukca	MetOffice/ukca@9fc2b6d	True

Task Information

✅ succeeded tasks - 1216

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Performance Impact

• Performance of the code has been considered and, if applicable, suitable performance measurements have been conducted

AI Assistance and Attribution

• Some of the content of this change has been produced with the assistance of Generative AI tool name (e.g., Met Office Github Copilot Enterprise, Github Copilot Personal, ChatGPT GPT-4, etc) and I have followed the Simulation Systems AI policy (including attribution labels)

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(Please alert the code reviewer via a tag when you have approved the SR)

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.

[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.

[cjohnson-pi]

main has been merged (including changes from #655). trac.log has been regenerated.

There is data to be copied to BIG_DATA_DIR. We need to agree on how to deal with the MetOffice/simulation-systems#660. The choices are:

1. Copy the files as is and add a file detailing where the ancil has come from (I have asked around and there doesn't seem to be an agreement on what this should look like yet).
2. Copy the files and add a file stipulating that they are only for internal use (as they are only for the weekly tests which are not run by partners).
3. Reduce the set of data contained in the files so that there are only the fields required (and hence removing the ancil data that requires licensing).

[cjohnson-pi]

I suggest that extracting the essential data is the best option at present. Therefore the files to be copied are (on exa and exc):

/data/users/christine.johnson/lfric_data/lfric2lfric/rho_theta_C896_t1.nc to /data/users/lfricadmin/data/lfric2lfric/C896/PR660/rho_theta_C896_t1.nc

/data/users/christine.johnson/lfric_data/lfric2lfric/rho_theta_zh_C224.nc to /data/users/lfricadmin/data/lfric2lfric/C224/PR660/rho_theta_zh_C224.nc

This has been tested at exa:/home/users/christine.johnson/cylc-run/realistic/run21/share/output/lfric2lfric