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NJ and GRIB-2 support for projected grids

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  • Subject: NJ and GRIB-2 support for projected grids
  • Date: Tue, 25 Mar 2014 19:40:27 +0000
John,

A Panoply user at NOAA wrote in to inquire about handling of a GRIB-2 data 
using an Albers equal-area conic projected grid. They weren't sure if there was 
a problem with Panoply or if they were doing something wrong in writing the 
dataset. As best I can tell, the issue is that the netCDF-Java library's 
support for projected grids is not as extensive for GRIB-2 files as it is for, 
say, netCDF files using the CF convention.

Using NJ to open the dataset, it is failing in the factory method of the 
ucar.nc2.grib.grib2.Grib2Gds class. The class is throing an 
UnsupportedOperationException because the Albers conic is temp-late ID 31, 
which is not one of the cases that the factory method handles. On the other 
hand, there is support for the Albers conic elsewhere in NJ's 
ucar.unidata.geoloc.projection package.

Is handling of Albers conic in GRIB-2 something that can be added to NJ soon? 
If you need a sample dataset, the file we are working with is currently 
available at ftp://ftp.opc.ncep.noaa.gov/data/albers/20140214_viirs_s.grb2

Thanks,

rbs



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