[MITgcm-support] GM Visbeck

[Olivier Arzel]

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