[MITgcm-devel] difference between EXFtaux & oceTAUX

[Menemenlis, Dimitris (3248)]

Hong, in addition to differences under sea ice, another possible difference
is that ustress can be scaled by exf_outscal_ustress and computed at
tracer points instead of C-grid velocity points.  See exf_mapfields:

          IF ( stressIsOnCgrid ) THEN
           do j = jmin,jmax
            do i = imin+1,imax
              fu(i,j,bi,bj) = exf_outscal_ustress*ustress(i,j,bi,bj)
            enddo
           enddo
          ELSE
           do j = jmin,jmax
            do i = imin+1,imax
c     Shift wind stresses calculated at Grid-center to W/S points
              fu(i,j,bi,bj) = exf_outscal_ustress*
     &              (ustress(i,j,bi,bj)+ustress(i-1,j,bi,bj))
     &              *exf_half*maskW(i,j,1,bi,bj)
            enddo
           enddo
          ENDIF

For most applications you want to use oceTAUX, not EXFtaux.
EXFtaux was introduced mostly for debugging purposes.

Dimitris Menemenlis

On Jun 30, 2011, at 4:37 PM, Jean-Michel Campin wrote:

> Hello Hong,
> 
> I am not sure I know precisely the answer to your question,
> and for this reason, I will cc to mitgcm-devel (in particular
> for the EXF part).
> From what I know, I would assume that the 2 sets of diagnostics
> are identical, except where there is sea-ice, because what
> EXF computes over sea-ice is not relevant ; on the contrary
> oceTAUX & oceTAUY are precisely what enter the ocean,
> wind-stress over ice-free ocean, sea-ice to ocean stress
> under sea-ice, and a weighted combination of both over
> partially covered grid-cell.
> 
> Thanks,
> Jean-Michel
> 
> On Thu, Jun 30, 2011 at 09:10:07AM -0700, Hong Zhang wrote:
>> Hi JM,
>> quick question for you.
>> What's the difference between  EXFtaux & oceTAUX in diagnostics?
>> available_diagnostics.log shows
>>>  166 |EXFtaux |  1 |       |SU      U1|N/m^2           |zonal
>>> surface wind stress, >0 increases uVel
>>>  167 |EXFtauy |  1 |       |SV      U1|N/m^2
>>> |meridional surface wind stress, >0 increases vVel
>> and
>>>   74 |oceTAUX |  1 |    75 |UU      U1|N/m^2           |zonal
>>> surface wind stress, >0 increases uVel
>>>   75 |oceTAUY |  1 |    74 |VV      U1|N/m^2
>>> |meridional surf. wind stress, >0 increases vVel
>> in exf_diagnostics_fill.F, EXFtaux is filled with ustress in
>> diags_oceanic_surf_flux.F, oceTAUX filled with fu.
>> Are they different? or redundant?
>> Could you explain a little more?
>> 
>> thanks
>> hong
> 
> _______________________________________________
> MITgcm-devel mailing list
> MITgcm-devel at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-devel