Cell volume interface for JELF

[Josh Colclough (mo-joshuacolclough)]

PR Summary

Sci/Tech Reviewer: DrTVockerodtMO
Code Reviewer: mo-lucy-gordon

This PR exposes a get_cell_volumes method for use in JEDI. A prerequisite to call this method is to set up init_fem. In the contexts where this method is required (use of a $J_c$ term in JEDI), this will certainly be called. It did however make this function tricky to unit test, as it would require a lot of science code to be called. It was decided to leave a test out for this subroutine.

• blocks JEDI MetOffice/lfric-jedi/issues/1324

Code Quality Checklist

• I have performed a self-review of my own code
• My code follows the project's style guidelines
• Comments have been included that aid understanding and enhance the readability of the code
• My changes generate no new warnings
• All automated checks in the CI pipeline have completed successfully

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)
• I have added tests to cover new functionality as appropriate (e.g. system tests, unit tests, etc.)
• Any new tests have been assigned an appropriate amount of compute resource and have been allocated to an appropriate testing group (i.e. the developer tests are for jobs which use a small amount of compute resource and complete in a matter of minutes)

I have tested this change works with JEDI. A PR is in the works to make use of this new function. See MetOffice/lfric-jedi/issues/1324.

trac.log

Test Suite Results - lfric_apps - jelf_cell_volumes__100826/run5

Suite Information

Item	Value
Suite Name	jelf_cell_volumes__100826/run5
Suite User	joshua.colclough
Workflow Start	2026-08-12T12:17:01
Groups Run	developer

Dependency	Reference	Main Like
casim	MetOffice/casim@2026.07.1	True
jules	MetOffice/jules@2026.07.1	True
lfric_apps	mo-joshuacolclough/lfric_apps@cell_volume_interface	False
lfric_core	MetOffice/lfric_core@60fc29a	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

❌ failed tasks - 3

Task	State
rose_ana_lfricinputs_um2lfric-protogal-N320L70_C12L70_ex1a_gnu_fast-debug-64bit	failed
run_gungho_model_robert-moist-smag-BiP100x8-10x10_azspice_gnu_fast-debug-64bit	failed
run_lfricinputs_um2lfric-protogal-N320L70_C12L70_ex1a_gnu_fast-debug-64bit	failed

✅ succeeded tasks - 1211

⌛ waiting tasks - 2

Task	State
housekeep_azspice	waiting
housekeep_ex1a	waiting

Security Considerations

• I have reviewed my changes for potential security issues
• Sensitive data is properly handled (if applicable)
• Authentication and authorisation are properly implemented (if applicable)

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)

Documentation

• Where appropriate I have updated documentation related to this change and confirmed that it builds correctly

PSyclone Approval

• If you have edited any PSyclone-related code (e.g. PSyKAl-lite, Kernel interface, optimisation scripts, LFRic data structure code) then please contact the TCD Team

Sci/Tech Review

• I understand this area of code and the changes being added
• The proposed changes correspond to the pull request description
• Documentation is sufficient (do documentation papers need updating)
• Sufficient testing has been completed

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

Code Review

• All dependencies have been resolved
• Related Issues have been properly linked and addressed
• CLA compliance has been confirmed
• Code quality standards have been met
• Tests are adequate and have passed
• Documentation is complete and accurate
• Security considerations have been addressed
• Performance impact is acceptable

[DrTVockerodtMO]

Changes look good to me! The logic behind not adding a unit test is also sensible.

[Josh Colclough (mo-joshuacolclough)]

A note to reviewers: A couple of tests have failed. They are unrelated to this change.

[David Davies (DJDavies2)]

Although my usual complaint: I don't like functions that return pointers.

[Matthew Hambley (MatthewHambley)]

Code owner (build system) review: No problem with these changes. A couple of observations, to consider.

[Matthew Hambley (MatthewHambley)]

If you want you can just say IMPORT_PARTS = $(INTERNAL_DEPENDENCIES). Only when they are the same, of course.

[Josh Colclough (mo-joshuacolclough)]

Thanks good to know. I'll leave this for now since this doesn't include adjoint

[Matthew Hambley (MatthewHambley)]

Indentation seems to have gone awry. Spaces would be preferred here, rather than tabs.

[Josh Colclough (mo-joshuacolclough)]

Thanks I've actually reverted this since it was not supposed to be in this change, not sure how it managed to make it in...