[MITgcm-support] best practice for ggl90

[Martin Losch]

Hi there,

I am trying to use pkg ggl90 in a global llc90 simulation and I am getting a lot (too much) deep mixing around Antarctica and (consequently?) grid scale patterns in velocity with some settings that I pulled from one of the verification experiments (global_ocean.90x40x15/input.idemix, but I am not using idemix). I assume that this is related to the mxlMaxFlag (=2 in my case), but also maybe to some other settings. When I use KPP instead, things look normal.

My experience with ggl90 is limited, so I could use some advice on what are the “best practice” choices for this package, in particular for the mxlMaxFlag.
I tried both ALLOW_GGL90_HORIZDIFF and ALLOW_GGL90_SMOOTH, both do some horizontal smoothing, unfortunately without success.

Thanks in advance,

Martin

PS. My other reference for llc90 runs: <https://github.com/ECCO-GROUP/ECCO-v4-Configurations/blob/master/ECCOv4%20Release%204/namelist/data.ggl90>
also has mxlMaxFlag=2,

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