Upgrade adjoint mixed solver

[DrTVockerodtMO]

PR Summary

Sci/Tech Reviewer: Josh Colclough (@mo-joshuacolclough)
Code Reviewer: allynt

This change includes an upgrade of the adjoint mixed solver code following from #177 . I have mainly added new kernels and adjoint tests. I have also included the adjoint for one of the kernels not used yet in the adjoint solver algorithm, because the conditional section that calls it in the linear has a not yet implemented error handling in the adjoint. If/when we are ready to code this we can have this method available at the very least.

• fixes Upgrade adjoint mixed solver #304

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)

trac.log

Test Suite Results - lfric_apps - upgrade_adj_solver/run11

Suite Information

Item	Value
Suite Name	upgrade_adj_solver/run11
Suite User	terence.vockerodt
Workflow Start	2026-08-19T12:20:16
Groups Run	developer

Dependency	Reference	Main Like
casim	MetOffice/casim@2026.07.1	True
jules	MetOffice/jules@2026.07.1	True
lfric_apps	DrTVockerodtMO/lfric_apps@upgrade_adj_solver	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

✅ succeeded tasks - 1218

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]

There is a problem with get_mask_r_solver trying to perform a halo exchange on a read-only field. The adjoint_tests app does use a special PSyclone config in order to get it to properly work in parallel since it uses setval_random. Since we don't use the test that gets the mask yet it might be worth just cutting that from the scope.

[Josh Colclough (mo-joshuacolclough)]

Looks good, I have a few considerations but not enough to fail sci review.

[Josh Colclough (mo-joshuacolclough)]

Wondering if these need dating? I see there are some files without dates.

[DrTVockerodtMO]

I was told in #428 to remove the dates so I think there is a new standard, not sure if its consistently applied though as I see some files still have the dates in.

[Josh Colclough (mo-joshuacolclough)]

Thanks good to know

[DrTVockerodtMO]

Oops, forgot to commit the kernel metadata fix until today, it should build properly now. I will run another dev suite!

[DrTVockerodtMO]

Oops, forgot to commit the kernel metadata fix until today, it should build properly now. I will run another dev suite!

Done.