[MITgcm-support] Issue with MITgcm Global Ocean Example

[Jean-Michel Campin]

Hi Abhirup,

I think the problem here is related to how MITgcm handle coordinates in NetCDF files
(in pkg/mnc) when using pkg/exch2, since "global_ocean.90x40x15" compiles and uses
pkg/exch2 whereas "tutorial_global_oce_latlon" does not.

I did not look where this is done in pkg/mnc but I suspect we wrongly assume
that using pkg/exch2 always means the grid is curvilinear (usingCurvilinearGrid=T)
and not Lat-Lon, but this is not always the case.

To confirm this, you could try to re-compile "global_ocean.90x40x15" without 
pkg/exch2 (in code/packages.conf), this should work with current code/SIZE.h 
(but not with code/SIZE.h_mpi which assumes 1 blank tile, that is only supported
with pkg/exch2); and re-run it to check.

Cheers,
Jean-Michel

On Mon, Oct 21, 2024 at 04:51:57PM +0000, Banerjee, Abhirup wrote:
> Dear MITgcm Support Team,
> 
> I am encountering an issue while trying to compile and run some of the provided examples in MITgcm. Specifically, I successfully compiled and ran the global_ocean.90x40x15 example without any issues. However, when I used gluemncbig to merge all the tiles, the grid in the resultant file did not appear correct. Upon inspecting the source file, tave.0000000000.t001.nc, I noticed that it does not seem to contain the expected grid values either.
> 
> The X and Y variables look like this:
> X = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
>     21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
>     39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56,
>     57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74,
>     75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90 ;
> 
>  Y = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
>     21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
>     39, 40 ;
> 
> Interestingly, when I ran the tutorial_global_oce_latlon example, everything worked perfectly.
> 
> Could you kindly provide guidance on how to resolve the grid issue in the global_ocean.90x40x15 example?
> 
> Thank you in advance for your support.
> 
> Best regards,
> Abhirup
> 
> Dr. Abhirup Banerjee
> Postdoctoral Researcher,
> Institut für Meereskunde,
> Bundesstr. 53, 20146 Hamburg,
> Universität Hamburg
> 
> 
> 
> 
> 
> 
> 

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