[Mitgcm-support] Re: kpp_freq

[mitgcm-support at dev.mitgcm.org]

Dear Fabiana,

the parameter kpp_freq sets the frequency at which the
the variable vertical mixing coefficients
KPPghat, KPPdiffKzT, KPPdiffKzS, KPPfrac
are updated/recomputed (see beginning of subroutine kpp_calc).
The purpose is to be able to avoid invoking KPP at every timestep
and thus save computing time, if desired.
So in your case you'd invoke KPP only every 300 timesteps
instead of every timestep.

Do I undestand correctly that you said, your mixing coefficients
were constant throughout the whole integration period?
Maybe something else is wrong, e.g. you forgot to set another
parameter 'useKPP' to .TRUE. in the file data.pkg?

-Patrick



Fabiana Cavazzon wrote:
> Dear Dr. P.Heimbach
>  
> I write you to ask some information about KPP package.
> In my experiment of the Gulf of Trieste on Adriatic basin, I introduce 
> the KPP package and the results of the KPPviscAz profile were consistent 
> with the result reported on Journal of Physical Oceanography 1999 volume 
> 30, page1888, "Resonant Wind-Driven Mixing in the Ocean Boundary Layer" 
> (E.D.Skyllingstad and W.D.Smyth).
> The last simulation ( 88x128x25 grid points with 250m of horizontal grid 
> spacing and 1m vertical grid spacing) was 5184000 seconds long (2 
> months) with dt=6 seconds; in this experiment I modified kpp_freq=1/2 
> hour (Re computational frequency for KPP parameters)  but the results 
> were different qualitatively and constant.
> Can you tell me more information about this parameter?
> Thank you in advance for your help
>  
> sicerely
>  
> Fabiana Cavazzon
>  
> ====================================================
> Fabiana Cavazzon
> Istituto Nazionale di Oceanografia e di Geofisica Sperimentale -OGS
> Borgo Grotta Gigante 42/c - 34010 Sgonico (TS)
> Italy
> ====================================================


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Patrick Heimbach ... Massachusetts Institute of Technology
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