[MITgcm-support] semi-prognostic calculation with MITgcm

[Chris Hill]

Samar,

 I think one way to do this is to

 (1) set saltStepping, tempStepping false
 (2) Have some initial T and S that are the external hydrography.
 (3) add two "passive" tracers that represent the transported T and S
      and that are forced however you want.

 The passive tracers can have GM, Redi, can mix convectively and according to
 boundary layer schemes like KPP, can have advection options etc....
just like T and S
 - but they won't change the hydrography.
 If you want the hydrography T/S to vary according to some imposed form, then
 you can  add rbcs bits to do that.
 Main thing to watch out for would be making sure hydrographic T/S are
statically stable.
 If they a unstable, convective mixing there will be continuous for
the tracers  - since I don't think
 the hydrographic T/S will get homogenized.

Chris

On Sat, Apr 10, 2010 at 1:20 AM, Samar Khatiwala <spk at ldeo.columbia.edu> wrote:
> Hello,
>
> Has anyone implemented/carried out a 'semi-prognostic' calculation with MITgcm? This is where you replace
> the model density (T/S) in the hydrostatic balance with an externally prescribed field, or a weighted average of the
> externally prescribed and model density field. The tracer equations are left unchanged.
>
> If someone had done this and can share their model mods with me, that would be fantastic. Any hints on how best to
> implement this would also be welcome. It wasn't entirely obvious which routine(s) to change. Is S/R CALC_PHI_HYD
> the one to change?
>
> Thanks very much,
>
> Samar
>
>
>
>
>
>
>
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