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MOM6 equation of state #20
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Note that this will determine whether the prognostic temperature is potential or conservative temperature, and the initial condition should match this - see #47 and COSIMA/access-om2#206. Or to put it the other way around, if we set up a config that uses the ACCESS-OM2 initial condition (which is conservative temperature), we need to use a matching equation of state in MOM6. |
I'm not sure if this also applies in MOM6, but in MOM5 the surface temp diagnostic is simply the prognostic temperature. If this is conservative temperature it differs from the potential temperature people normally think of when they want "SST", and so we need to output surface potential temperature as well - see COSIMA/access-om2#203 (comment) |
Using conservative surface temperature for the CICE |
Another wrinkle: ACCESS-OM2 uses the pre-TEOS10 EOS which is Jackett et al. 2006 (see COSIMA/access-om2#140), but AFAIK this EOS is not available in MOM6 so we were intending to use |
We may also need to be careful to use freezing point settings that are appropriate for the EOS we choose. |
My understanding is that we'll have to regenerate/modify the ACCESS-OM2 initial condition regardless of which EOS we choose?
The latter, however, potentially also requires changes to the NUOPC cap and elsewhere - from the comment on the
@aekiss, what's the best way forward here? Is there any value in first trying to get |
I saw in Jackett et al. 2006:
Is this still considered to be the case? |
I think it would be fine to do initial tests with Good point re. the surface values for diagnostics and (especially) coupling. If the MOM6 cap doesn't enable coupling with potential T we should discuss with other modelling groups to see how they manage it. In MOM5 this is controlled by Re. practical vs absolute salinity: I'm not sure how much they differ (OM2 uses a pre-TEOS10 EOS that uses practical salinity) - I'd need to look into it some more to find out what people normally do. |
Just noting that we need to be careful with setting the value of Cp in accordance with the EOS - see ACCESS-NRI/access-om3-configs#5 (comment) |
Upon reviewing the codebase for the utilization of
Within the Nuopc cap ( |
Thanks for looking in to this @ezhilsabareesh8. That's good news that the NUOPC cap already handles the conversion. So if we turn on The next question then is do we initially want to use an EOS that is the same/similar to the Then there's also the question of salinities. I think the ACCESS-OM2 initial conditions are conservative temps and practical salinities? But in MOM6 it doesn't appear to be possible to run with these as prognostic variables together. So should we:
Thoughts @aekiss |
The pressure gradient calculation may be a lot slower if we use anything other than
But that would be irrelevant if the pressure gradient calculation is a negligible component of the overall cost. |
See Bob's response to @adele-morrison: mom-ocean/MOM6#1592 |
Might be good to use |
related: #180 |
Just noting, the most recent MOM_input we have from GFDL OM5 still uses |
In our testing in mom6-panan @AndyHoggANU, @adele-morrison is that an acceptable price to pay? |
We would need to convert conservative temperature to potential temperature SST for coupling to CICE (and the UM in ACCESS-OM3). Does anyone know if this can be done in MOM6 or the CMEPS mediator? |
Does seem a surprisingly heavy price to pay. But I would like to re-test with our @minghangli-uni ’s current timing methods before we make a call … |
I thought this is already done in the NUOPC cap - see this comment above.
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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-2024/1734/16 |
We should choose a suitable equation of state.
ROQUET_RHO
looks good - see discussion: COSIMA/mom6-panan#24The text was updated successfully, but these errors were encountered: