Minutes of the code management group meeting 2026-07-09
From UKCA
(Redirected from Minutes of the code management group meeting 2026-07-10)
Teleconference Details
Thursday 9th July 2026, 10.00am - 11.30am GMT
Meeting via Teams - see link in calendar invitation
Met Office: MS, MD, AJH, AJ
Cambridge: NLA, RW
Leeds: DG, MR
Canterbury:
CSIRO:
Apologies: PMJ
NEXT MEETING WILL BE THURSDAY 10TH SEPTEMBER 2026, 10.00-11.30 GMT
Actions from this meeting
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. Graham has found code needed for meteoric smoke. Coding needed to get changes in. Have a way forward.
- DG hasn't had time due to UKESM1.3 etc. After Summer should have more time.
- (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. AJH working on the RADAER API. Have made notes in a different document, and then will merge into single document. Expected around September.
- AJH may put the 2 things together. At the moment are word documents. Lfric_apps documentation is moving along slowly and there are a lot of gaps, but is in markdown (.md) format. Should move science into UKCA, then smaller docs in UM and lfric_apps for interface documentation.
- MR - readthedocs might be better received by the academic community.
- RW - should be hosted in UKCA - GitHub good at doing static documentation that can be rebuilt in Actions.
- AJ - ACP 'living papers'?
- Split into 2 actions - RADAER API (AJH) and wider documentation more generally (??)
- (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.
- (ongoing) NLA / MD to put a link to Monsoon3 guide to GitHub in the minutes
- MD: GitHub user guide for Monsoon – the Monsoon3 user guide is linked from the ‘Community’ tab on Monsoon Teams channel: GitHub — Monsoon3 User Guide 1.0 documentation
- closed
- (ongoing) MD is developing workaround for Bug in Lfric copy of ukca_volcanic_so2. However, this will not add functionality in lfric. A developer for this needs to be identified. Lodged in LFRic, confirmed with May Chim and is happy to do for UM, but may have issues with testing.
- MD has asked May Chim whether she would be able to add the fix over the summer after the expected release.
- ongoing
- (ongoing) AJH to tidy up the priority table. Some items are now complete and should be marked as such.
- periodic exercise - closed
- (ongoing) AJH, MD, and PMJ to discuss method for checking diagnostic KGOs with NetCDF files.
- AJH has been assisting the AQ team with some issues. Will catch-up with PMJ offline.
- ongoing
Issues/PRs
REMEMBER TO LINK UKCA IN YOUR UM AND LFRIC_APPS (& OTHER REPO) ISSUES/PRs
RW is kindly doing the VM partner testing this release (UM14.2).
Matt Naylor is developing 3D chunking.
Issues
Pull Requests
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
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 |
|||
| 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. |
|||
| 158 | While analysing #156, it was noticed that in the UM version of `ukca_volcanic_SO2` the array weight_volc_vertdist is being populated without being allocated. | May Chim? | Since UM vn13.9 Needs to be allocated as weight_volc_vertdist(l2-l1+1) and deallocated in each iteration over nreupt |
||
| 159 | Logical l_ukca_prescribech4 should not be active in Strat schemes | In ukca_add_emiss the logical enables overwriting of CH4 surface values with prescribed concentrations. However, later on in the routine this action is repeated in a section specific to 'Strat' schemes, where use of prescribed vs emitted CH4 is governed by l_ukca_emisdrvn_ch4, thus over-ridding the first logical. Since UM vn11.x Should be turned Off in rose metadata for Strat schemes |
|||
| 160 | Mismatch in tracer names indexing across UKCA API. | Could be related to #143. Printing from UKCA_TRACER_COPY_TO/FROM_UM, and comparing all_tracers_names vs tr_names shows  misalignment  in names of species. Note: this may be just limited to the population of tr_names array as any actual misalignment would have been noticed for radiative feedback as well as tracers/ diagnostics in output Since UM vn10.6? |
|||
| 161 | Error using diagnostic 50-332 with chem version 132 ("RXN NOT FOUND J H2SO4 PHOTON -> SO3 OH") | Mohit says "I believe this means that for chem_schemes=121+ the reaction no longer yields just SO3 and OH? This would mean that there is a bug in asad_flux_dat where this extra product is not included in set of reactions for chem_scheme 121+." For 121+ the reaction now also yields H as well as SO3 and OH (see ukca_chem_master). Found in vn13.9 |
DG tried to turn it on but it didn't work. Potentially do with #128 |
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 |
|---|---|
MR - Helen Burns has been working with paeloscientists - may have found a bug, will investigate and may report it.
A.O.B. & D.N.M. (NLA)
Please fill in the UKESM survey: https://forms.gle/KB9QJQEwJys2BSgWA
Please fill the NERC/UKRI Atmospheric Science Forward Look review form: https://engagementhub.ukri.org/nerc-research-and-skills-directorate/atmospheric-science-forward-look/
