Objective Analysis

Discussion of how to use ROMS on different regional and basin scale applications.

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mbkprasad
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Objective Analysis

#1 Post by mbkprasad » Tue Apr 08, 2008 1:58 pm

Hi,

I have Dissolved oxygen data for a over a period of 10 yaers from different locations of the C Bay at defferent depths. Now I want to calculate DO climatology. I understand from available literature is the best way to do this by the Objective Analysis (OA). I am new to this field. Hence. I request you to kindly help me how to do this.
I downloaded OA package from ROMS.

Regards
MBKP

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aneeshcs
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Objective Analysis

#2 Post by aneeshcs » Wed Apr 09, 2008 2:46 am

Hi Prasad,

I have once used the Objective Analysis packaged developed at Harvard which was one of the suggested tools for ROMS OA. I'm not sure the ROMS Matlab toolbox OA code will objectively Map scattered data onto the model grid. The Harvard code was a fortran code which needed the input data to be in HDAT format. Could we know which OA code you intend to use?

Thx
Aneesh

mbkprasad
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#3 Post by mbkprasad » Wed Apr 09, 2008 1:52 pm

Hi Aneesh,
Thanks for your reply. For ROMS OA also the input data is to be in HDAT format. Plz. suggest me which one will be better?

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aneeshcs
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#4 Post by aneeshcs » Mon Apr 14, 2008 10:56 pm

Hi Prasad,

Sorry for the late reply..I just saw your post. If the ROMS OA package also needs HDAT format, then I think, the ROMS OA package is better. From what I remember ( I had used it 4 years back) you do get matlab and other fortran codes which read netCDF data and convert them to HDAT format. There were some detailed issues which I faced when I was working with the data I had. Like there were lots of zeros and I had to remove them from the HDAT format. Probably you will not have to face them! Do message if you find a problem in using the package, I shall try my best to suggest something useful..

Thx

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arango
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#5 Post by arango » Tue Apr 15, 2008 1:01 am

The OA package is very old :!: I have not updated those codes in years. I wrote the OA packages when I was at Harvard in the early 90s. I assume that both packages are very similar. I recommend to use the ones that we distribute in the ROMS website. Probably, they are newer. If you check ROMS website Pakages :arrow: Menu, you will notice that the OA package is fully documented and the HDAT format described. Also notice that a tar file :arrow: link is provided to download all the codes needed to create HDAT files. Users just need to read the information more carefully. :idea:

A couple of year ago, I discovered a much better way to store this type of hydrographic data in a NetCDF file. It uses the same strategy of no special values, like in the HDAT format. We use this format in ROMS variational data assimilation. At the moment, I don't have an intention to add the hydrographic NetCDF format to the OA package. Maybe in the future...

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