[MITgcm-support] KPP vertical diffusivity values

[Martin Losch]

Hi Hadar,

values >1m^2/s are OK in convection. 

KPP is a complicated beast. I suggest that you read Large et al 1994 to understand how it works. 

The main routines are in collected in kpp_routines.F.
First STATEKPP computes buoyancy gradients and expansion/contraction coefficients etc
CALC_3D_DIFFUSIVITY only computes the background kappa (which can contain many things not related to KPP, in Large et al 1994 this would be just a constant representing internal wave mixing etc. in the quiescient ocean interior)
KPPMIX then computes the KPP-mixing coefficients for the actively mixing layer.

Martin


> On 26. May 2017, at 12:53, Hadar Berman <hadarberman at gmail.com> wrote:
> 
> Hi,
> 
> I am using the KPP package for my oceanic model. When I check the resulting values of KPPdiffKzS, i.e. the vertical diffusion of the tracers, during convection I get values which are higher then 1 m^2/s. Are these typical values for convection? If so, how and where are they calculated?
> Going into the code I see that kpp_calc.F first calls calc_3d_diffusivity and only later KPPmix. I am trying to understand where these values are computed and if they make any sense. 
> 
> Thanks,
> Hadar.
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