[MITgcm-support] Zonal and vertically averaged diagnostics

[Jean-Michel Campin]

Hi Andrea,

You could try to define a "region mask file" with several stripes of constant 
longitude but only 1 grid point wide, and try to use the stats-diags 
within pkg/diagnostics (an example in global_ocean.cs32x15/input.thsice,
DIAG_STATIS_PARMS namelist in data.diagnostics).
Not 100% sure this will give exactly what you want, need to try.

Cheers,
Jean-Michel

On Thu, Nov 10, 2011 at 01:51:48PM +0000, cimatori wrote:
> Thanks!
> 
> This makes things actually a lot easier. I would have preferred to do
> all the diagnostics on-line, but if the standard is computing integrals
> off-line, then I'll go for that.
> To answer your question, volume (or salt) transport across any latitude
> depends on the surface forcing (freshwater flux or virtual salt), and
> I'm interested in different components of the flux (diffusion, eddy,...)
> that are non-zero in any case.
> 
> Andrea
> 
> 
> 
> On 11/10/2011 01:37 PM, Ryan Abernathey wrote:
> > Hi Andrea,
> >
> > I think what you want to do is fairly standard. The MITgcm has
> > extensive diagnostics built in. But it doesn't take spatial integrals
> > for you--it just does time averages. To do zonal and depth integrals,
> > you have to process the diagnostic output offline. Most people do this
> > using MATLAB or python. Make sure you check out the
> > available_diagnostics.log output by the diagnostics package to see
> > which diagnostics are available in your configuration.
> >
> > Computing a mass (volume) budget is fairly trivial. You simply
> > integrate the transports (UVEL, VVEL, WVEL) across whatever surface
> > you want using the proper grid geometry. (The output grid files can be
> > very useful for this.) Correct me if I'm wrong, but the zonal- and
> > depth-integrated volume transport across any latitude in the basin you
> > described should be zero, no?
> >
> > Budgets for salt or any other tracer should be fairly straightforward
> > to compute as well. The diagnostics package automatically makes the
> > necessary fluxes available through variables like ADVx_SLT, DFxE_SLT,
> > surForcS, etc. It provides these values averaged at every grid point.
> > If you want to compute a budget for a different volume, you have to
> > integrate the fluxes yourself off-line.
> >
> > Conservation of volume is very good in MITgcm, up to numerical
> > precision. Budgets for other tracers (heat, salt, etc.) can be more
> > difficult do close exactly if you have many different packages enabled
> > (gmredi, kpp, etc.), but for a simple setup you should be able to do it.
> >
> > Hope this helps.
> >
> > Cheers,
> > Ryan
> >
> >
> > On Nov 10, 2011, at 5:44 AM, cimatori wrote:
> >
> >> Dear MITgcm users,
> >>
> >> I have a question on diagnostic output, hope it's not too trivial...
> >>
> >> I am interested in computing a mass budget (both total mass and salt
> >> mass) for a basin with simple geometry (box+periodic channel), and I
> >> would like to output some transport terms integrated both zonally and
> >> vertically. In other words, I want to compute the budget at each
> >> different latitude from south to north (keeping the northern boundary
> >> fixed). This means that I would have to output a vector with the size of
> >> the number of grid points along y.
> >> As fas as I could understand, this doesn't seem to be a standard choice
> >> for the diagnostics package. Did anybody try something like this? Is
> >> there some tutorial case including an example?
> >>
> >> Apart from this, is there any reference on how good or bad the mass
> >> budget in MITgcm might be?
> >>
> >> Any suggestion would be of great help, thanks!
> >> Andrea
> >>
> >> _______________________________________________
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> >> MITgcm-support at mitgcm.org
> >> http://mitgcm.org/mailman/listinfo/mitgcm-support
> >
> >
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> 
> 
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