[MITgcm-devel] Bug in KPP

[Dimitris Menemenlis]

David, yes I do use KPP + Bryan-Lewis and yes there does appear to be  
a mismatch in vertical diffusivity and viscosity but haven't had time  
to look at it in detail.

Looking back in CVS, the vertical profiles for background vertical  
diffusivity in kpp_routines was enabled in going from version 1.20 to  
1.21 and became fully 3D in going from 1.25 to 1.26.

What I am not clear on is whether the correction for mismatch should  
occur
in ri_iwmix in transferring KPPvisc and KPPdiff to vdfiff or in
kpp_calc in transferring vddiff back to KPPvisc and KPPdiff

there is a possiblity that both of these options are wrong depending on
whether vddiff is defined at the tracer points or at the interface?

D.

On May 25, 2009, at 8:19 PM, David Ferreira wrote:

> Hi,
> I found a bug in KPP. The bug comes in subroutine Ri_iwmix when KPP
> is used with variable vertical diffusivities (for example with Bryan- 
> Lewis).
>
> Is anybody concerned by this ? Dimitris, you use KPP and Bryan-Lewis
> in the cube-sphere, no ?
> Cheers,
> David
>
>
> In case you care, the problem appears because the diffusivities in KPP
> are carried
> in a Nr+2 long vector with k=0 at the surface while the  
> diffusivities in
> the normal
> form of the MITgcm are in a Nr-long vector with k=1 at the surface.  
> But,
> in Ri_iwmix,
> the 2 are matched with the same k...
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