[MITgcm-support] netcdf with curvilinear grid

[Martin Losch]

Hi Chris,
sorry to be imprecise.
Here <http://mitgcm.org/~mlosch/gridfiles.tar> you'll find a tarball  
with all input grid files (for both OLD_GRID_IO define and  
undefined), and the output grid.t00[1,2].nc for the OLD_GRID_IO case.  
There are two separate problems:

1. with OLD_GRID_IO defined the second tile netcdf output is flipped  
(grid.t002.nc, you'll notice the shapes of England/Ireland look funny  
in HFacC, etc.). The model runs fine and give reasonable results, and  
rdmnc.m can even read all output files and put them together  
properly. glumnc can not do that.
2. with OLD_GRID_IO undefined I have not been able to make the model  
read the grid information properly (I did not talk about this problem  
in my previous email). Processor 1 is OK (reads from  
tile001.mitgrid), but Processor 2 reads also from tile001.mitgrid and  
thus the same grid information as Processor 1, so that I have a  
domain that's twice the lower half of the domain. I have also tried  
to have only one tile001.mitgrid with everything in it, but even then  
Processor 2 only reads the part that was meant for Processor 1 only  
(indecent sob, that Processor 2).
Interestingly for this configuration, the netcdf output for  
HFacC,Depth, etc is OK, so not flipping of the j-index, very strange.

Can you make anything of this?

Martin

On 30 Jan 2008, at 14:03, chris hill wrote:

> Martin,
>
>  I can't quite figure out which thing does/doesn't work from your  
> message.
>
>  The commas confused me!
>
>  Can you put your tile* files somewhere. As long as they are good,  
> everything will work.
>
> Chris
> Martin Losch wrote:
>> Hi there,
>> I am using a curvilinear grid much like Dimitris Menemenlis'  
>> arctic configuration. It's based on a rotated grid where the north  
>> pole has been rotated to the equation, etc. I divide my domain  
>> into two tile for two processors:
>> snx=243
>> sny=85
>> nsx=1
>> nsy=1
>> npx=1
>> npy=2
>> so Nx=243, Ny=170
>> I have now managed to get the model to read the grid  
>> usingCurvilinearGrid=.true. (BTW, only the OLD_GRID_IO variant  
>> works, with the the tile00?.mitgcm, I run it all sorts of  
>> problems, but that's a different question), and everything seems  
>> to run OK. But the netcdf output is unexpected. The first tile  
>> comes out OK, but the second tile, which should be on top of the  
>> first one is flipped, it basically runs from j=170 at the bottom  
>> backwards to j=86 at the top.
>> Probably as a consequence, Baylor's fantastic script gluemnc does  
>> not work and it puts the two tiles next to each other (so that I  
>> get a domain Nx=2*243,Ny=85).
>> Matlab's rdmnc on the other hand seems to be doing the right thing  
>> and flips the 2nd tile back to normal.
>> What's going on?
>> Martin
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>
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