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ACCESS-OM2 global ocean - sea ice coupled model configurations.
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Forcing ACCESS-OM2 with wind stresses #160

Open rmholmes opened 5 years ago

rmholmes commented 5 years ago

I am putting this here as others may want to do the same in the future (or have already done so in the past!).

For Shweta's PhD project we would like to run some ACCESS-OM2 simulations forced directly with wind stress. We want to do some experiments where we remove the seasonal cycle in the wind forcing. If we do this with wind speed then we will get incorrect mean stresses because of the non-linearity.

Is it possible with yatm to force access-om2 with input wind stress fields from a file (obtained from another access-om2 run) instead of wind speeds?

One problem is that we also want to keep the bulk flux formulation for the heat fluxes, which require wind speed magnitude. Is it possible to input wind speed magnitude as an additional forcing field (I've done this with ROMS before)? Alternatively, we could hack the system by replacing, say, the zonal wind speed input field with the wind speed magnitude (since the direction shouldn't matter). The idea would be to replace all forcing fields with monthly averages (but account for the most important non-linearities while doing so).

Any hints/suggestions on how to go about this would be great. @nichannah perhaps?

russfiedler commented 5 years ago

Passing wind speed magnitude from CICE->MOM5 is something that I've half done. It's needed for Wombat and langmuir wave mixing. It's in CM2. If the wind stresses are only being used for the ocean and not the ice you can use the data_override feature in MOM. A bit inconsistent but may be worth considering.

rmholmes commented 5 years ago

Ok great, it looks like we can do wind stress directly into MOM easily just by adding lines in the ocean/data_table (through data_override). However, this means that the ice will still be pushed around by the stress calculated from the input wind speeds? We would want to override the entire atmosphere -> ice stress if possible.

I'll have a look at the CM2 stuff

russfiedler commented 5 years ago

Aha there some code in cice5/source/ice_forcing.F90 that almost does exactly what you want. Look for routine prepare_forcing_from_oasis. If you set calc_strair=.false. you just get stresses that are read in. A slight change to the logic should allow you to get all the fields in. Just got to make sure that the stresses aren't overwritten in the main surface flux routine.

rmholmes commented 5 years ago

Ok, great thanks Russ.