Minutes of the code management group meeting 2025-11-13
Teleconference Details
Thursday 13th November 2025, 10.00am - 11.30am GMT
Meeting via Teams - see link in calendar invitation
Met Office: MD, AJH, MS, PMJ, JCK, CN
Cambridge: NLA, RW
Leeds: DG
Canterbury: CH
CSIRO: AL
Apologies:
NEXT MEETING WILL BE THURSDAY 8TH JANUARY 2026, 10.00-11.30 GMT
NOTE: NLA will not be able to make the 8th Jan 2026
ACTION: AJH to chair next meeting
Actions from this meeting
- (ongoing) GM/DG to update table on UKCA wiki documenting GLOMAP versions. DG/GM to consider the code and lodging process for GLOMAP developments and consider a suitable rose-stem test supported by NLA. GM Will work with DG to get a subset to commit. AJH to review. Graham has found code needed for meteoric smoke.
- (ongoing) AJH on update API document to UM13.6 release. NLA to provide feedback before it is be circulated. There is a comprehensive overhaul for 13.7. AJH to make document available for wider information/comment - see here. AJH won't do anything with API until GitHub release is out, and then will add some things to it.
- (ongoing) ALL look at um:#6203 showing other unprotected rose-stem options and think about any code/settings they are interested in. May be able to use GitHub actions.
- (ongoing) ALL to consider ordering of the Progress with Priorities table and highlight things that should be higher priority, and any other tasks that need to be included.
- (new) AJH to chair next meeting
- (new) NLA to mention MASS issues at the next MMG
- (new) NLA to put a link to Monsoon3 guide to GitHub in the minutes
Actions from the Last Meeting
- (ongoing) GM/DG to update table on UKCA wiki documenting GLOMAP versions. DG/GM to consider the code and lodging process for GLOMAP developments and consider a suitable rose-stem test supported by NLA. GM Will work with DG to get a subset to commit. AJH to review.
- Ongoing. Graham has found code needed for meteroic smoke.
- (ongoing) AJH on update API document to UM13.6 release. NLA to provide feedback before it is be circulated. There is a comprehensive overhaul for 13.7. AJH to make document available for wider information/comment - see here.
- Ongoing. AJH won't do anything with API until GitHub release is out, and then will add some things to it.
- (ongoing) ALL look at um:#6203 showing other unprotected rose-stem options and think about any code/settings they are interested in.
- Ongoing - may be able to use GitHub actions.
- PMJ has been working on the column model in rose-stem, but hasn't made much progress. Will pick this back up.
- AJH has microplastics rose-stem tests ready, but had some KGO issues so wasn't committed. May need to change compiler settings. Thread sanitizer found some issues but still seems to be happening intermittantly.
- (ongoing) ALL to consider ordering of the Progress with Priorities table and highlight things that should be higher priority, and any other tasks that need to be included.
- Ongoing
- (new) NLA to look at DGs ukca:#304
- Closed
- (new) MD to set up a nudged Monsoon3 UKESM suite based on u-dr799
- Closed
- Errors could be from the radiation namelist
- Some issues with MASS archiving, might be worse on Monsoon3
- ACTION: NLA to mention at MMG
Tickets
PLEASE REMEMBER TO USE THE UKCA KEYWORD FOR ALL UKCA CHANGES (ESPECIALLY IMPORTANT FOR OTHER REPO TICKETS)
PLEASE REMEMBER TO USE THE LINKED:UM or LINKED:APPS KEYWORDS IN YOUR UKCA TICKET FOR LINKED CHANGES
PLEASE REMEMBER TO USE THE LINKED:UKCA KEYWORD IN YOUR LINKED UM and/or APPS TICKETS
NOTE: The requirement for LFric testing of all changes under UM:src/atmosphere, UKCA:src/science, and UKCA:src/control/core
Please also give any feedback on the UM release cycle to NLA to pass-back to UM Sys.
Message from UM Sys - please take care when considering keywords. It is important to get these correct for the Code Review process.
Last Release
NOTE THAT THIS IS THE LAST RELEASE THAT WILL USE FCM - AFTER THE RELEASE IT WILL THEN MOVE TO GITHUB
See: https://github.com/MetOffice/simulation-systems/discussions/394
While not tagged, version 14.0 will be head-of-trunk versions. This is tagged as git_migration (r7497 for UKCA, r131675 for the UM) at HEAD. There are instructions on the Monsoon user guide about how to access GitHub. Support for MOSRS should be available for at least a year to allow for migration of workflows, but this is subject to change.
There was some uncertainty who would update UKESM suites - it may be MS. AJH also discovered a bug in the microplastics code and the water content code that has been fixed.
The next code freeze is likely to be in May, but this is still unconfirmed.
ACTION: NLA to put a link to Monsoon3 guide to GitHub in the minutes
Progress with Priorities (NLA)
ACTION REQUEST FROM UKCA SCIENCE & MANAGEMENT BOARD: CMG to provide list of priorities & their status, with particular thought to UKESM2 changes that will be required.
Progress with Priorities table
For diagnostics it was decided to have 2 levels
Diagnostic infrastructure and high priority diagnostics that are needed for auto-assess and the UKCA evaluation suite (new #7)- All other diagnostics (new #11 after GPU work)
For people who are using LFRic, only imode_setup=8 works for RADAER. AJH is aiming to get back to expanding this list of options in December.
Bugs/Bugfixes (NLA)
Open Bugs
| # | Description | Ticket | Owner | Comments | Comments from this meeting |
|---|---|---|---|---|---|
| 124 | H2 and N2 cannot be set for RCP and WMOA1 scenario routines | UM:#5620 vn13.8.1_ukca_rcp_read_h2_n2 | Mohit | Values are hard-wired in the code and cannot be changed without a branch. N2 values seem to be read from namelist (for UM, and RCP scenarios). Branch adds possibility to read H2 from either RCP or namelist. Will probably require updating all UKCA-chem apps to maintain KGO. More testing required MD has done a little bit of work. N2 is read from namelist, but can now read from RCP file for H2 |
|
| 128 | Bug in UKCA stratospheric chemistry diagnostics | UM:#5839 | Luke Abraham | The indexing/values of diagnostics m01s50i101-i104 are incorrect. Fixes provided for vn11.1 and vn11.7. May affect CMIP6 diagnostics Does this need fixing for CMIP7? Need to discuss with CDDS/diagnostics team as might break existing workflow. |
|
| 143 | Error in print statements from UKCA_TRACERS_COPY_FROM_UM | Not yet | ??? | The final species listed in the diagnostic print statement seems to have very large concentrations (O(1E+08)) compared to others in the ppm-ppt range. Does not seem to affect model output. Reported by James Weber. | |
| 144 | interchangeable use of specific humidity and water vapour mixing ratio | #6813 | John Hemmings and ??? | UKCA includes calculations of relative humidity, clear-sky relative humidity and saturation vapour pressure. Relative humidity calculations should be based on water vapour mass mixing ratio but are in part based on specific humidity. Also, the calculation of saturation vapour pressure is derived from saturation mixing ratio but uses a formula for deriving SVP from saturation specific humidity. This interchangeable use of specific humidity (ratio for moist air) and mixing ratio (ratio for dry air) in existing configurations introduces small numerical errors in UM and LFRic model runs. These bugs were identified at UM version vn12.2 and have been highlighted by comments in code lodged with UM ticket #6660 (in ukca_main1-ukca_main1.F90 and atmos_ukca_humidity_mod.F90). All UKCA configurations are affected. Alan - This should be fixed by Met Office. I will speak with Anthony and Alistair about resourcing to fix this. It requires good understanding of humidity to work through this problem, otherwise I would have done this myself. When we pass stuff through the argument list, the name changes which makes things complicated. Should we pass a structure with all the humidity fields in? There is a UKCA bespoke version of humidity calculations for non-UM applications. Internal Met Office problem - will need to find someone to fix it. AJH to talk with AJ and Alistair Sellar. GM can cross-check. Ticket has 2 parts. JH suggests doing it in 2 tickets, 1 technical, 1 bug fix. JH could do technical part (either as callback routines or separate fields). Then would need UM & LFRic tickets for the bug fix, as calculations could be done in the parent or as callback routine. Some work has been done - technical change has been done in ukca:#245. Went in at UM13.9. This option is now used by the UM and LFRic. Buggy calculations are now outside of UKCA - will require UM and LFRic changes to fix those. Might not be a large amount of work, but problem needs to be well understood. Also consider what field is being passed in the tracer list - currently q but should be mixing ratio. Some has been fixed - bug has been shifted outside of UKCA. Don't know of anyone working on it currently. Someone will need to go through and check we are passing the correct one - need someone on aerosol side and on chemistry side |
Also has problems with GLOMAP-clim |
| 153 | bug in 2D photolysis | While working on developments for the new photolysis API, we’ve noticed a likely error in the current implementation of the 2D photolysis. The 2D photolysis files are tabulated by day of year at 5-day resolution, amongst other variables. The interpolation to the actual day of year is currently done in the read subroutine (read2d_opt or read2d_orig). However, this subroutine is only called once on the first timestep. For multi-day runs, the photolysis rates will not be updated as the day of year increases. Since nobody is using the 2D photolysis at the moment this is likely of low to no impact. Might be used by NUAQ BD or VB will know more - PMJ will ask |
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| 154 | bug in tropospheric heterogeneous chemistry | Within GLOMAP the wetdp variable is defined as the wet diameter in m. However, in ukca_trop_hetchem this is used as a radius in cm. This results in a factor of 50x error. Steve Turnock might be using this. NLA to contact ST and YG about this. |
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| 155 | OMP dynamic scheduling race condition | ukca:#321 | When using OpenMP with dynamic, as opposed to the standard static, scheduling, checksums were failing with lfric_apps. This indicates a race condition likely within the ASAD chemical package and so would affect the UM as well as LFRic. Further testing is needed. | AJH will make some time to run it with the thread santizer |
Redundant Code (NLA)
Code for deletion
PLEASE REMEMBER TO EDIT THE ORIGINAL REDUNDANT CODE TABLE AND NOT THIS PAGE
Desirable Science not tested
PLEASE REMEMBER TO EDIT THE ORIGINAL SCIENCE NOT TESTED TABLE AND NOT THIS PAGE
See also the complete list of unprotected rose-stem options
| # | Description | Ticket | Remarks | Owner |
|---|---|---|---|---|
| 1 | Use of tropospheric (2D) look-up table photolysis | Still useful to compare against FastJX. May be used for a "fast" configuration. Will be doen as part of photolysis refactoring | ||
| 2 | TropIsop chemistry configuration | May be useful in a "fast" configuration & to drive GLOMAP-mode. Useful for low-top configurations. | ||
| 3 | Strat chemistry configuration | Useful for stratospheric studies, particularly with a high model top. | Luke Abraham |
Round (virtual) Table of current activities, plans
| Person | Activity |
|---|---|
| AJH | Updated has pcalc values of nitrate and would like the updated values to be used in UKESM2, but doesn't have a lot of time for the testing. He may email Jane. This is expected to be a negligble change, but would require a 50-year coupled run to test. |
A.O.B. & D.N.M. (NLA)
AL asked whether dust part of GLOMAP now, or still CLASSIC? AJH and MS clarified that GAL9 isusing GLOMAP dust (imode_setup=8 rather than 2). There should be standalone climate suites soon for GAL9 with GLOMAP dust and it is already in NWP suite. Should also be in GC5 and UKESM.
NLA hightlight that the next UKCA training is in January, and costs will be fully covered for participants.
