[MITgcm-support] Underestimated ETA values for Global Ocean!

[Menemenlis, Dimitris (3248)]

Hi Abhisek, if you use
MITgcm_contrib/mitgcm_tools/mitgcmhistory.m
(or grep) to look at variables dynstat_eta_mean and dynstat_salt_min
in STDOUT, you will probably find that eta_mean is gradually
decreasing and salt_min gradually increasing as a function of
time.  This would mean that EmPmR (evaporation minus precipitation
minus runoff) is unbalanced in your surface forcing, specifically
that that there is more evaporation than precipitation and runoff,
so that your model domain is loosing mass.
I suggest that you compute this imbalance term and then add it
to your precipitation.  I'd probably use a global "multiplicative" rather
"additive" factor to avoid flooding regions that are supposed to
receive little rain --- although I suspect that this factor will be small
and that your SSS relaxation term would compensate for any excess
rain in such regions.

Cheers, Dimitris

On Mar 16, 2013, at 2:31 AM, Abhisek Chakraborty wrote:

After spinning up the model for 500 years and then running the model with monthly NCEP fields, I found that temperature, salinity, currents are matching well with GODAS (NCEP), but surface elevation (ETA) is underestimated (though the patterns are matching with GODAS). I have attached one simulation result ( you can see negative elevation in most of the places). Can anybody please guide me how to correct this?

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