[MITgcm-support] T, S budget in the surafce layer

[Cerovecki, Ivana]

Dear MITgcm world,

we would like to close temperature and salt budget with SOSE output. The SOSE uses implicit 
free surface. What is the correct way to close the T/S budget in the surface layer to account for 
heat/salt change at the surface. 

To follow up on Jean-Michel’s earlier comment (pasted below) – is the best way to
set linFSConserveTr=.TRUE. In that case, is the correction that the model makes saved in 
ADVr_TH output diagnostics, or in order to close the budget accurately in the top layer 
do we need to use what Dimitris suggested in an earlier post:

For the surface surface level, can't the divergence term be computed 
ADVx_TH(i,j,1) - ADVx_TH(i+1,j,1) + ...  
ADVy_TH(i,j,1) - ADVy_TH(i,j+1,1) + ... 
ADVr_TH(i,j,2) - WTHMASS(i,j,1) * RAC(i,j) 

which obviously implies we need to output WTHMASS and WSLTMASS fields.

We would very much like to close T/S budgets as accurately as possible, so I will be very grateful 
if you could please let me know what needs to be done for the top layer,
Ivana 

P.S. With all the work that ECCO and the other people have done diagnosing various budgets, is there 
maybe a version of the scripts to diagnose T/S budgets available somewhere?


Jean-Michel: 
http://mitgcm.org/pipermail/mitgcm-support/2011-May/007205.html

“with Linear FreeSurf, there is a small loss of heat/salt/tracer  at the surface (d/dt(Eta) inconsistent with fixed surf grid cell thickness): 

a) if linFSConserveTr is set to true (file "data"), then the model    correct for this (see S/R calc_wsurf_tr.F). 

b) if linFSConserveTr=False (=the default), need to account for this term  in the budget, which can be obtain from the 1rst level of WTHMASS / WSLTMASS   diagnostics (diagnostics ADVr_TH / ADVr_SLT is not the right one for   this purpose, it's just zero at k=1).  “