[MITgcm-support] why fresh water flux not recommened together with salinity restoring for adjoint

[Martin Losch]

I think that it means the same thing (“not recommend with … restoring” sound like “better with surface restoring” (than turned on freshwater flux). In the end both salinity restoring and freshwater flux imply a forcing for salinity. If you use only freshwater flux with temperature restoring, that’s called mixed boundary conditions and those then to lead to very sensitive set ups (check out old paper about that). Maybe these comments refer to that.

Martin
> On 1. Sep 2022, at 19:51, dong.jian at studium.uni-hamburg.de wrote:
> 
> 
> 
> Hi all,
> 
> I am doing adjoint sensitivity experiment with global ocean simulation "global_ocean.90x40x15"
> Does someone know why it say fresh water flux not recommened together with surface salinity restoring for adjointin
> 
> https://github.com/MITgcm/MITgcm/blob/master/verification/global_ocean.90x40x15/input_ad/data
> # fresh water flux is turned off, uncomment next line to turn on
> # (not recommened together with surface salinity restoring)
> # EmPmRFile=      'ncep_emp.bin',
> 
> while in the forward configuration it is the opposite:
> https://github.com/MITgcm/MITgcm/blob/master/verification/tutorial_global_oce_latlon/input/data
> 85# fresh water flux is turned on, comment next line to it turn off
> 86# (maybe better with surface salinity restoring)
> 87 EmPmRFile=      'ncep_emp.bin',
> 88 &
> 
> just not sure if I should turn it off for sensitivity experiment, and why only SSS, not SST?
> 
> many thanks,
> Dong
> 
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