[MITgcm-support] CS Grid Generator and Convertor Matlab Scripts

[Chris Watkins]

I'm afraid this hasn't worked. The XG and YG data seem to be wrong.

In the attached two plots I have plotted RA against XG and YG  on a sphere.
Plot CS2.ps uses data from the tileNNN.mitgrid files supplied with the
code. It looks just as you would expect with regions of smaller RA (blue)
at the 'corners' with larger RA (deep red) in between at the equator and
poles.

However, in plot CS1.ps I use data XG, YG and RA from the tileNNN.mitgrid
files produced by the matlab code. The plot is not at all as one would
expect. There are 'corners' but they are malformed and regions of deep red
appear displaced, for example there are no deep red regions at the poles.

Finally in CS3.ps I use XC, YC and RA from the matlab code and it looks
fine. This suggests to me that XG and YG are not what I expect them to be.

Sorry for all the attachments I thought that they would best illustrate my
issue.

Regards,

Chris



On 16 February 2012 07:45, Chris Watkins <chris at tw1.me.uk> wrote:

> Yuan,
>
> Thanks for all your help.
>
> Regards,
>
> Chris
>
>
> On 15 February 2012 23:04, Yuan Lian <lian at ashimaresearch.com> wrote:
>
>>  Hi Chris,
>>
>> Glad you figured out the problem. The C32 grids supplied in the
>> verifications examples may have different configuration, likely they used
>> different nratio, or with some extra tweaks about the cube-sphere grid
>> corners (some grid stretching etc).  One way to ensure that the grids were
>> generated correctly is to compare "XG, YG ..." during grid generation and
>> those from the .bin files. Additionally you take a look of the grid
>> arrangement in "EXCH2" section in the MITgcm manual, from which you can
>> check if "XG" and "YG" generated by the matlab routines make sense.
>>
>> The extreme values I mentioned in the 2004 thread were caused by the
>> machine format, i.e., big endian and little endian. As long as your XG and
>> YG values are confined within the bounds (-180, 180) for XG and (-90,90)
>> for YG, you are good to go.
>>
>> Best,
>> Yuan
>>
>>


-- 
Chris Watkins

G+ GPlus.to/ChrisWatkins <http://gplus.to/ChrisWatkins>
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