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[GEMPAK #ZHX-668060]: decoding ERA40 grib files

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  • Subject: [GEMPAK #ZHX-668060]: decoding ERA40 grib files
  • Date: Fri, 13 Apr 2007 16:35:39 -0600
Kevin,

The GRIB1 gaussian grids cannot be stored into a GEMPAK grid file because
the distance between grid rows is not constant. It would require an 
interpolation
of the points to a regular spaced grid (that hasn't been developed yet).

I have been able to use Gaussian and reduced gaussian grids in GRIB2 format
since I can store the GRIB2 data in its native format without unpacking
(eg the ECMWF TIGGE ensemble on a 800x400 reduced gaussian grid) and
display the gaussian rows (though the position is off a little at the poles).

Another user a while back found that the same data was available on a 2.5x2.5 
degree
lat/lon grid which satisfied her needs.

Steve Chiswell
Unidata User Support


> We are unable to decode some grib files from the ERA40 data set.  The
> problem is an "unknown projection 4":  specifically, navigation is unable
> to be set since the value of "gds.grid_proj" is 4, while the relevant
> function in dcgrib2 only accepts 0, 1,3,5, and 203. Is there any way to
> decode these files into GEMPAK grids?
> 
> Thanks,
> 
> Kevin
> 
> ______________________________________________________________________
> Kevin Tyle, Systems Administrator               **********************
> Dept. of Earth & Atmospheric Sciences           address@hidden
> University at Albany, ES-235                    518-442-4578 (voice)
> 1400 Washington Avenue                          518-442-5825 (fax)
> Albany, NY 12222                                **********************
> ______________________________________________________________________
> 
> 
> We are unable to decode some grib files from the ERA40 data set.  The
> problem is an "unknown projection 4":  specifically, navigation is unable
> to be set since the value of "gds.grid_proj" is 4, while the relevant
> function in dcgrib2 only accepts 0, 1,3,5, and 203. Is there any way to
> decode these files into GEMPAK grids?
> 
> Thanks,
> 
> Kevin
> 
> ______________________________________________________________________
> Kevin Tyle, Systems Administrator               **********************
> Dept. of Earth & Atmospheric Sciences           address@hidden
> University at Albany, ES-235                    518-442-4578 (voice)
> 1400 Washington Avenue                          518-442-5825 (fax)
> Albany, NY 12222                                **********************
> ______________________________________________________________________
> 
> 


Ticket Details
===================
Ticket ID: ZHX-668060
Department: Support GEMPAK
Priority: Normal
Status: Closed