[MITgcm-support] How to diagnose the diapycnal diffusivity?

[Martin Losch]

As far as I know, the parameters \kappa_{\rho} and \kappa_{GM} are constant parameters that you specify in data.gmredi (from GMREDI.h:
C     GM_isopycK       :: Isopycnal diffusivity [m^2/s] (Redi-tensor)
C     GM_background_K  :: Thickness diffusivity [m^2/s] (GM bolus transport)
). You  can have variable \kappa_{GM} (documentation: <https://mitgcm.readthedocs.io/en/latest/phys_pkgs/gmredi.html#variable> ), but you need to turn it on explicitly with the appropriate CPP- and runtime-flags, and then GM_VisbK is the approriate diagnostics for this particular version of variable \kappa_{GM}.
In recent code, there are all sorts of other options that I am not familiar with, but they maybe worth exploring.

Martin


> On 16. Jul 2018, at 13:57, yzb <853245241 at qq.com> wrote:
> 
> 
> Thanks for you reply. Sorry for the confusion of my question. This is something I should have written more about the diapycnal diffusivity. The diffusivity I want to calculate is the diapycnal mixing ( ,unit is m^2/s), maybe can be regarded as eddy coefficient. I am not sure the  which is in the Gmredi pkg can be represented for it. There is a diagnostics option in Gmredi pkg which is called 'GM_VisbK' and this may be relate to my question.
> 
> ------------------ Original ------------------
> From:  "Martin Losch"<Martin.Losch at awi.de>;
> Date:  Mon, Jul 16, 2018 07:35 PM
> To:  "MITgcm Support"<mitgcm-support at mitgcm.org>;
> Subject:  Re: [MITgcm-support] How to diagnose the diapycnal diffusivity?
> 
> Yang,
> 
> when you run your model with a default debugLevel (=1), then you’ll a file called “available_diagnostics.log”, that will show you all diagnostics for your particular configuration. If you have turned on GM (useGMredi=.TRUE. in data.pkg), then you the GM-diagnostics should be part of that list. I am not sure if there is a diagnostic for diapycnal diffusivity (do you mean diffusive flux?) …
> 
> Martin
> 
> > On 16. Jul 2018, at 11:12, yzb <853245241 at qq.com> wrote:
> > 
> > Hello,
> > 
> >      I want to diagnose the diapycnal diffusivity directly from model. But I don't know the diagnostic name of it. Could anyone tell me the diagnostic name? Meanwhile, I found the package of Gmredi may contain this diagnosis. If so, what's the diagnostic name in that package? 
> > 
> >     Thanks,
> >     Yang
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> 
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