Linear 32bit

[cjohnson-pi]

PR Summary

Sci/Tech Reviewer: @tom-j-h
Code Reviewer: @stevemullerworth

Enable the tangent linear and adjoint models to use 32 bit precision and test.

• Update the adjoint_tests and linear_model iodef files so that W2 fields are not written out. This also includes splitting the iodef files into many small iodef files (to mirror the gungho_model iodef files) - this makes it easier to manage going forward.
• Correct the diagnostics source code so that xios only tries to write out fields if they are listed in the iodef file. (32 bit does not work for writing out W2 fields).
• Update the plotting to plot winds in W3 rather than W2 (as W2 are no longer in the diagnostic file).
• Update the adjoint test parameters to avoid dividing by zero errors.
• Add 32bit and 64bit tests, and with a variety of compilers, to the rose stem tests for linear_model and adjoint_tests. For adjoint_tests, slightly different solver settings are required for 32bit and 64 bit.

#111

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 Core rose-stem suite
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trac.log

Test Suite Results - lfric_apps - linear_32bit/run7

Suite Information

Item	Value
Suite Name	linear_32bit/run7
Suite User	christine.johnson
Workflow Start	2026-01-20T10:33:37
Groups Run	suite_default

Dependency	Reference	Main Like
casim	MetOffice/casim@2025.12.1	True
jules	MetOffice/jules@2025.12.1	True
lfric_apps	cjohnson-pi/lfric_apps@linear_32bit	False
lfric_core	MetOffice/lfric_core@5d4d72f	True
moci	MetOffice/moci@2025.12.1	True
SimSys_Scripts	MetOffice/SimSys_Scripts@2025.12.1	True
socrates	MetOffice/socrates@2025.12.1	True
socrates-spectral	MetOffice/socrates-spectral@2025.12.1	True
ukca	MetOffice/ukca@2025.12.1	True

Task Information

✅ succeeded tasks - 1151

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Performance Impact

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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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Sci/Tech Review

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Code Review

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