Switching to Symmetric MOM6

[helenmacdonald]

Regional MOM6 needs to run on a symmetrical executable whilst access-om3 is running on a non-symmetrical executable. Switching access-om3 to symmetrical will reduce the number of executables that need to be supported.

The difference between symmetric and non-symmetric mom6 is that there is some overlap of grid cells on adjacent tiles. This uses a very small amount of extra memory but may make some gradient calculations easier. The central version of MOM6 runs tests to ensure that switching between symmetrical on non-symmetrical does not change the model solution but we may need to test on the access-om3 models to ensure that this is still the case with our parameterisations.

The suggestion is that we should compare a test case of access-om3 run in symmetrical and non-symmetrical mode to check that there are no issues before switching over

[access-hive-bot]

This issue has been mentioned on ACCESS Hive Community Forum. There might be relevant details there:

https://forum.access-hive.org.au/t/cosima-twg-meeting-minutes-2025/4067/2

[anton-seaice]

I built with mom_symmetric and the normal repro test passes. .

In my view that is enough to make the change ?

[chrisb13]

Agreed and good timing!

[anton-seaice]

Yay - it only impacts the deployment, so ill put the change in deployment repo (probably ACCESS-NRI/ACCESS-OM3#33)

[chrisb13]

Yeah, makes sense. I just noticed that it's already there, though isn't it? Here, specifically.

[anton-seaice]

Yes - I was predicting the future there ;-)

[anton-seaice]

This has been implemented in ACCESS-NRI/ACCESS-OM3@6ef4337