[MITgcm-support] Zonal and vertically averaged diagnostics

[cimatori]

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
>>
>> _______________________________________________
>> MITgcm-support mailing list
>> MITgcm-support at mitgcm.org
>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>
>
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support