[MITgcm-support] GM Visbeck

[Jean-Michel Campin]

Hi Oliver,

I think you are right: there is an option (through GM_background_K & GM_isopycK)
to use different K for Redi and GM, but this possibility is not
coded for GM_Visbeck.

Something we may want to add in the future.
But did not check in pkg/gmredi code how easy it would be to add
this option.

Cheers,
Jean-Michel

On Thu, Mar 24, 2016 at 11:22:01AM +0100, Olivier Arzel wrote:
> Hi
> 
> I am doing some quick tests to see how the model stores quantities
> associated with the GM parameterization (with GM_AdvForm=.TRUE.)
> 
> When I run the model with constant Kgm and zero Redi diffusion, the
> diffusive tracers fluxes are indeed zero (bolus transport and
> eulerian mean combined to
> form the residual mean). Here is my data.gmredi for this case.
> 
>  &GM_PARM01
>   GM_AdvForm         = .TRUE.,
>   GM_AdvSeparate     = .FALSE.,
>   GM_background_K    = 1000.0,
>   GM_isopycK         = 0.0,
>   GM_taper_scheme    = 'gkw91',
>   GM_maxSlope        = 1.e-2,
>   GM_Kmin_horiz      = 0.,
>   GM_Scrit           = 4.e-3,
>   GM_Sd              = 1.e-3,
> # GM_Visbeck_alpha   = 0.,
> # GM_Visbeck_length  = 2.e+5,
> # GM_Visbeck_depth   = 1.e+3,
> # GM_Visbeck_maxval_K= 2.5e+3,
>  &
> 
> 
> However when I run the same experiment but using a variable Kgm
> (Visbeck), the diffusive terms become non-zero. I do not see why
> this should be the case.
> 
> Here is the data.gmredi that I use. (I also use in all experiments
> implicitDiffusion=.TRUE.)
> 
>  &GM_PARM01
>   GM_AdvForm         = .TRUE.,
>   GM_AdvSeparate     = .FALSE.,
>   GM_background_K    = 0.0,
>   GM_isopycK         = 0.0,
>   GM_taper_scheme    = 'gkw91',
>   GM_maxSlope        = 1.e-2,
>   GM_Kmin_horiz      = 0.,
>   GM_Scrit           = 4.e-3,
>   GM_Sd              = 1.e-3,
>   GM_Visbeck_alpha   = 0.07,
>   GM_Visbeck_length  = 5.e+4,
>   GM_Visbeck_depth   = 2.e+3,
>   GM_Visbeck_maxval_K= 1.e+3,
>  &
> 
> Any help would be greatly appreciated
> Thanks
> Olivier
> 
> 
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