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Re: [netcdf-java] Decoding NDFD Severe Weather product Problem



On Tue, 4 Jan 2011, Jeff Brogden wrote:

Hello,

I have successfully used netcdf-java to open NDFD products as a GridDataset. The problem I'm having is that the Severe Weather products use the local use section of the GRIB2 message to embed a weather string table that is used to create the "colorbar" or legend for that product.

From the NDFD website.
"Cell values in the data part of the GRIB2 message are numbers which refer to the entry in the weather string table."

How do I read the local use section out of the GridDataset formated GRIB2 data so I can use it to build a proper legend from the data?

Hi Jeff,

The current grib decoder doesn't have a path to access the LocalUseSection directly. The grib library needs to be refactored to permit this option. With that being said, attached is a standalone program called GetLocalUseSection that takes 1 or 2 parameters, input Grib file and optional output file that reads the LocalUseSection of the first record in the Grib file. Since my test cases didn't have any files that use the LocalUseSection the code is untested. Could you send a sample file so it can be added to the test cases? My thinking was you could decoder the LocalUseSection and then add those parameters. Hopefully this will provide a path to the LOcalUseSection until the Grib Library can be refactored.

Here's an url from NDFD about LocalUseSection( section 2 ). From the documentation, it imples that these parameter might be static, could just
be my interpretation.

http://www.weather.gov/forecasts/graphical/docs/grib_design.html

RObb...





Any help would be appreciated.  Thank you.

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Jeff Brogden    CIMMS/OU
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Robb Kambic                                Unidata Program Center
Software Engineer II                       Univ. Corp for Atmospheric Research
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