Thanks for documenting this process @tammasloughran.
Just so others know and find the correct repo, all the CLEX CMS ACCESS-ESM1.5 experiments are in branches in this repo:
My recollection was that the payu versions did reproduce the original experiments, but my memory is terrible and I wasn’t directly involved in most of the verification. @holger and/or @Scott may be better placed to say for sure.
They would also be well placed to comment on the UM configuration.
Checking bitwise reproducibility is possible just by comparing the checksums in the UM logs. There is comment here from @MartinDix about this
which also mentions mule-cumf , which maybe answers your other question about comparing fields?
If you want ACCESS-NRI assistance with this add a help tag to the post and it’ll be picked up by the triage team.