MetOffice / MetOffice/simulation-systems
Where can I (should I) add a temp logical in LFRic?
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Description
There is a desire to treat temporary logicals different in LFRic to the UMs single namelist approach. Once a system is agreed the [temporary logical page in the working practices](https://metoffice.github.io/simulation-systems/Development/temp_logicals.html) should be updated to reflect the different systems.
### Discussed in https://github.com/MetOffice/simulation-systems/discussions/603
Originally posted by **MichaelWhitall** March 18, 2026
Hi all,
I have a minor bug-fix that I want to lodge in lfric_apps, affecting the PC2 cloud-scheme (the final item in the bullet-list on this issue page: https://github.com/MetOffice/lfric_apps/issues/243). I think in the past it would've been said, if it clearly fixes a bug, just change the code without using any switches as noone will mind a KGO-change for that. But as we get ever-closer to having a frozen and highly-tuned LFRic GC6, I'm guessing that's no-longer the case? In the UM I always ended up having to lodge cloud-scheme bug-fixes under "temporary logicals", because they usually cause a small change in cloud radiative forcing (which is something that has to be finely tuned in the climate model and so mustn't be changed in a frozen configuration).
What's the process for lodging this sort of bug-fix in lfric_apps? I've found the old UM `science_fixes_mod` still exists in lfric_apps, but could be retired as currently `um_physics_init` just sets the relevant logicals to true; none of them are in a namelist. Should I just add a switch to toggle on/off the bug in the LFRic cloud namelist? Or does lfric_apps have its own equivalent to temp logicals somewhere that I've missed?
Cheers!
Mike
Contributor guide
Research direction
Start by reading the discussion linked from issue 604 and the temporary logicals page in the working practices. Determine the agreed LFRic process for temporary logicals, then update that page to describe the resulting system and how it differs from the UM approach.
Written by the indexing model from the issue text.
Assessment
- Domain
- documentation
- Issue type
- Documentation
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100