[MITgcm-support] Re: AMOC estimation in cs grid

[ESTANISLAO-GAVILAN-PASCUAL-AHU]

Hi Jean-Michel, thanks so much for your help. I will take a careful look to your those scripts.


Kind regards,


Estanislao







>----------------------------------------------------------------------
>
>Message: 1
>Date: Thu, 31 Aug 2023 18:35:07 -0400
>From: Jean-Michel Campin <jmc at mit.edu>
>To: mitgcm-support at mitgcm.org
>Subject: Re: [MITgcm-support] AMOC estimation in cs grid
>Message-ID: <20230831223507.GA39061 at ocean.mit.edu>
>Content-Type: text/plain; charset=us-ascii
>
>Hi Estanislao,
>
>To compute the AMOC (or, in general, the Meridonal Overturning Circulation) it is recommended
>to NOT interpolate the horizontal velocity before integrating zonally and vertically the meridional
>transport. The main reason is that the interpolation will not preserve the small divergence of
>the flow field, resulting in large artificial error.
>
>The recommended method is to direcly integrated the transport on the original model grid,
>following the edges of grid-cell that are close to a latitude target, along a "broken line".
>
>The matlab script to generate these "broken lines" and to use these to compute the MOC
>are in the process of beeing updated, see PR #729, https://github.com/MITgcm/MITgcm/pull/729
>I would advise to check this updated version (rather than the original scripts in
> MITgcm/utils/matlab/cs_grid/bk_line) because the updated method is simpler and therefore
>easier to convert into python:
>>From this branch: https://github.com/jm-c/MITgcm/tree/update_matlab_cs_grid
> in: MITgcm/utils/matlab/cs_grid/
> from the "README" file, lines 65-70:
>> mk_isoLat_bkl.m :: define "broken-lines" as close to latitude-target vector
>>         "yLat", for computing Meridional Transport stream-function.
>>         => write matlab file: isoLat_${ydim}_cs32.mat (with ydim = length(yLat))
>> use_bk_line.m :: an example that uses "isoLat_59_cs32.mat" to compute & plot
>>         Meridional Transport Stream-function.
>> 
> and the 2 matlab scripts are there.
>
>Cheers,
>Jean-Michel
>
>On Thu, Aug 31, 2023 at 12:57:26PM +0800, ESTANISLAO-GAVILAN-PASCUAL-AHU wrote:
>> Dear Community,
>> 
>> 
>> I want to evaluate the amoc in my cs grid. I can linearly interpolate the u and v transport to the grid's centre, then compute the meridional component using the anglesn and anglecs. That should give me the meridional transport in the curvilinear grid. The last step is, to sum up or plot cross sections the points at the same latitude. Is there a method that does not require interpolating from curvilinear to a regular latlon grid? Thank in advance for your help in this matter.
>> 
>> Kind regards,
>> 
>> 
>> Estanislao
>> 
>> 
>> 
>> 
>> 
>
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>
>
>
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