Meeting Minutes (02/09/2025)
Participants: @MartinDix, @spencerwong, @Aidan, @tiloz, @Jhan, @matthew.chamberlain, @manodeep, @anton, @micael, @clairecarouge, @dhb599, @alexnorton, @inh599, @sofarrell, @harshula, @pearseb, @paulleopardi
Ocean albedo and temperature drift
@MartinDix has done 50 year tests with the AprilSpinup configuration, scaling the ocean albedo by 0.96 and 0.92. 0.92 is much more effective at reducing the temperature drift. While 0.92 sounds like a drastic change, the resulting albedo is much closer to CM2 which used the Jin parameterisation. 0.92 also better matches the CERES data, which also uses the Jin parameterisation.
@MartinDix will see whether it’s possible to implement the Jin parameterisation in ESM1.6, as it may be preferable to the scaling approach.
Configuration for further ocean albedo tests
@MartinDix will test the albedo changes with an updated configuration. It was decided to include as many as the planned changes as possible for these tests, in order to use a configuration as close as possible to a final configuration. Along with the change to CICE5, further changes to be incorporated are:
- Possibly the Jin albedo parameterisation @MartinDix
- Water balance changes @spencerwong
- Wombat crash fix @dougiesquire (already in)
- oneAPI and openmpi5.0.8 @manodeep and @spencerwong
A decision is needed on where to start the tests. @matthew.chamberlain notes that the ocean BGC reached a stable state during the JuneSpinup, and somewhere at the end of AprilSpinup or JuneSpinup could be a good starting point. @pearseb notes that later restarts with a more spun-up BGC state aren’t necessarily better, as physics changes make the completed spin up less useful.
It was decided to branch from two points in parallel. This will require CICE5 compatible restarts (@anton).
Mediteranean salinity issues were discussed, however it was decided they weren’t currently important for the global scale problems currently being focused on.
Wombat crash
@dougiesquire has fixed the intermittent wombat crashes, and created new executable and configuration releases. He can help if anyone wants to bring the fix into their existing simulations.
Openmpi5.0.8
@manodeep and NCI have solved an issue previously preventing us from using openmpi 5.0.8. The new version improves performance, putting the model on par, if not slightly better than ESM1.5.
AugustSpinup run
It was decided to stop the AugustSpinup simulation as we’ll be using an earlier restart.
Land changes
@RachelLaw and @alexnorton will work on the land changes in parallel. The changes are currently working, however @RachelLaw will investigate an issue where swapping between CN and CNP modes change meteorology when the feedbacks are switched off.
Next meeting
Next week’s meeting will be cancelled due to the workshop.