Vertical Mixing Coefficient AKT_BAK for oxygen

[Yunli]

I recently began to run Fasham model for oxygen dynamics. Just a quick start with physics, I switched off
(1) all nitrogen stuff by setting rOxNO3 and rOxNH4 to zero in ./Nonlinear/fasham.h,
(2) and NitriR=0.0d0 in ./External/Biofasham.in.

I noted that in bioFasham.in, there is a parameter AKT_BAK for biological tracers, and I assume that it works for the vertical mixing of dissolved oxygen. Am I right?

If so, I tried a bunch of values, e.g.10^-4,10^-5,10^-6,...,0.0d0, but there were no significant differences between all the cases, and my O2 mixed up quickly from a stratified initial distribution. Could someone direct me into the subroutines, which calculate vertical mixing of O2 by use of AKT_BAK for oxygen? It may be worthwhile to check if the program is actually passing the value(showed in biofasham.in) around in the model loop.

[kate]

Note that Akt_bak is used to set the value of Akt in the absence of any other vertical mixing scheme, such as GLS or KPP. Akt is dimensioned by the number active tracers (T and S, usually), not by all the tracers. It is used in pre_step3d with:

Code: Select all

ltrc=MIN(NAT,itrc)
   ...
              FC(i,k)=cff3*cff*Akt(i,j,k,ltrc)*                          &
     &                (t(i,j,k+1,nstp,itrc)-                             &
     &                 t(i,j,k  ,nstp,itrc))

This means that whatever happens to be in Akt for salinity is what all of the bio tracers get. You may well have a surface mixed layer with high values of Akt, depending on how you set it up.