[MITgcm-support] how to compute water flow through ocean sections with gmredi / kpp ?

[David Ferreira]

Hi Alexandre,
KPP does not contribute to the water (volume) flux through a section, KPP only includes vertical fluxes.
GMredi does not either. Redi only acts on tracers (other than density). GM has a zero net contribution because the streamfunction is zero at top and bottom.
If you care about meridional transport, the net flux is given by the Eulerian overturning streamfucntion, the value at the very top is not quite zero and equals the net transport (assuming the streamfunction was computed by integrating from bottom up).

Last remark, the interpolated/rotated velocities are not appropriate to compute the net flux, it is very inaccurate. The computation must to be done on the native grid.

cheers,
david

________________________________
From: Alexandre Pohl [pohl at cerege.fr]
Sent: Friday, April 07, 2017 4:42 AM
To: mitgcm-support at mitgcm.org
Subject: [MITgcm-support] how to compute water flow through ocean sections with gmredi / kpp ?

Dear all,

I want to compute water fluxes through given sections in the ocean. For a latitudinal profile for instance, I compute the zonal flow at a given depth as follows:
F = nansum(uEz(profile1).*(dz.*hfacWz(profile1)).*dyg(profile1))/1E6; % (Sv, positive eastward)
with
- profile1: the section made of several grid points;
- uEz = UVELMASS at the depth of interest rotated using 'rotate_uv2uvEN' (I use the CS grid).

Since I use GMRedi and KPP, I think that I should include some additional terms, but I don't know how to do that.
Any help would be greatly appreciated !

Thanks,
Alexandre



__

Alexandre POHL
Postdoctoral Researcher
CEREGE, TECHNOPOLE ENVIRONNEMENT ARBOIS-MEDITERRANEE
BP80, 13545 AIX en PROVENCE, CEDEX 04, FRANCE
https://alexandrepohl.org






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