UKNCSP CDDS-CMIP7-mappings

This repository is being used for collection and review of model configuration for the UKESM1-3 and HadGEM3-GC5 based models being prepared for CMIP7 submission in 2026.

Mapping and STASH information

Information is being held for each mapping in the body of github issues, e.g. #67 contains the information for monthly mean surface air temperature (Amon.tas). Within each issue there are three tables; the first for Data Request information, second for mapping information and the third for STASH setup.

The information in the issues is also presented in the following files;

• data/mappings.json (JSON representation of the data in each issue)
• data/mappings.csv (Excel CSV representation of Data Request and Mapping information)
• data/stash.csv (Excel CSV representation of STASH information)

Github will provide an interface to search CSV files, but the mappings.csv file is above the size limit on this service (512 K) so the mappings are also presented in a set of files organised by realm;

aerosol atmosChem atmos landIce land ocean ocnBgchem seaIce

Note that there are separate files for variables which were present in CMIP6 and those that appear to be new in the data subdirectory.

Automatic processes (github actions) regenerate these files as issues are added or updated (see here).

Prerequisites for the Review process

Anyone with a github account can comment on issues, but to edit the body of the github issues and contribute to the mappings/STASH setup review process users will need to be registered. To do this please fill out this form.

Review process

Information is extracted from the "body" of each issue and updates should be made by editing its content (see image below for pointer to button)

This will trigger actions to update the information in the data files linked to above.

Once your review is complete please add the "approved" label to the issue and add a comment confirming that you are happy with the mapping and STASH entries.

If you have questions please add the "question" label to the issue. We will attempt to answer questions and remove that label when we think we've answered them.

Note that comments are ignored by the automated process so can be used for queries or discussions

Mappings update

To update the mapping add an extra row to the mappings table for the corresponding model (UKESM1-3 or HadGEM3-GC5. For example to extend the mapping for Amon.tas (#67) change the mappings table from

Field	Value	Notes
Expression UKESM1	m01s03i236[lbproc=128]
Expression HadGEM3-GC31	m01s03i236[lbproc=128]
Model units	K

to

Field	Value	Notes
Expression UKESM1	m01s03i236[lbproc=128]
Expression HadGEM3-GC31	m01s03i236[lbproc=128]
Expression UKESM1-3	m01s03i236[lbproc=128]
Expression HadGEM3-GC5	m01s03i236[lbproc=128]
Model units	K

More complex mappings, i.e. those which require some post processing, use python functions to produce the required data. One example of this is Amon.tasmax (#68) which uses a mon_mean_from_day in order to perform the necessary calculation. These "processor" functions are all written in python, take multiple iris cubes as arguments and return an iris cube which is then passed on to CMOR for writing. The set of processor functions used in CMIP6 can current be found here.

If post-processing of data is required for a variable and a processor does not already exist please add the processor label to the issue. Additional information on processors should be added as a comment to the issue.

STASH entries update

To support configuration of the UM atmoshpere output each issue also tabulates the corresponding entries to be included in the STASH setup. If possible this table should be extended in a similar fashion to the one for the mappings, but with a row for each STASH code required.

For example Amon.zg (geopotential height on pressure levels) in #78 has the expression m01s30i297[blev=PLEV19, lbproc=128] / m01s30i304[blev=PLEV19, lbproc=128] for both models so requires two lines in the STASH table for each model;

Model	STASH	Section, item number	Time Profile	Domain Profile	Usage Profile
UKESM1	m01s30i297	30,297	TMONMN	PLEV19	UP5
UKESM1	m01s30i304	30,304	TMONMN	PLEV19	UP5
HadGEM3-GC31	m01s30i297	30,297	TMONMN	PLEV19	UP5
HadGEM3-GC31	m01s30i304	30,304	TMONMN	PLEV19	UP5

To extend the same STASH requirements to the HadGEM3-GC5 and UKESM1-3 models extend the table to

Model	STASH	Section, item number	Time Profile	Domain Profile	Usage Profile
UKESM1	m01s30i297	30,297	TMONMN	PLEV19	UP5
UKESM1	m01s30i304	30,304	TMONMN	PLEV19	UP5
HadGEM3-GC31	m01s30i297	30,297	TMONMN	PLEV19	UP5
HadGEM3-GC31	m01s30i304	30,304	TMONMN	PLEV19	UP5
UKESM1-3	m01s30i297	30,297	TMONMN	PLEV19	UP5
UKESM1-3	m01s30i304	30,304	TMONMN	PLEV19	UP5
HadGEM3-GC5	m01s30i297	30,297	TMONMN	PLEV19	UP5
HadGEM3-GC5	m01s30i304	30,304	TMONMN	PLEV19	UP5

Diagnostic review

Where mappings and STASH requirements have not materially changed from CMIP6 definitions we do not intend to produce sample data for Science QA review as these mappings have already been heavily tested.

Variables that are very similar to existing ones, e.g. where they only differ in frequency, will likely not require Science QA review.

All new variables will need to go through a Science QA review process to ensure that we have the capability to produce the data correctly.

Differences between HadGEM3-GC5 and UKESM1-*/HadGEM3-GC31 models

Please note that the HadGEM3-GC5 configuration uses both a new configuration of NEMO (conservative potential temperature and absolute salinity as prognostics) and the SI3 model rather than CICE for the sea-ice component. Mappings will need to take this into account when adding information for HadGEM3-GC5 in particular.