[gradsusr] Problem extracting HIRLAM gribfile

Wesley Ebisuzaki Wesley.Ebisuzaki at noaa.gov
Fri Mar 11 14:08:24 EST 2011


Jonas,

   Your grib1 file is packed using "complex packing".  This kind of 
packing is
not supported by grib2ctl and GrADS. 

   I think that you are getting the error message because the grid is 
(582 x 424) or 246768 points.
However, the number of grid points (could be modified by undefineds and 
runs of identical values)
is given by octets 19-20 in section 4. Since 246768 much too big to be 
stored in a 2 byte number,
an error is flagged.  Try converting this file to grib2 using the ECMWF 
software.  Once in grib2,
g2ctl and GrADS can read it.  I don't think that g2ctl will handle the 
projection right but at least you
can display it as a x-y grid.

> http://www.nco.ncep.noaa.gov/pmb/docs/on388/section4.html


    Wesley Ebisuzaki

Jonas Kaufmann wrote:
> Hello,
>
> I ran into a problem trying to extract a HIRLAM data set on a rotated
> lat-lon grid. the file is in grib1-format. I could create a valid
> control file using the code from g2ctl.pl for grib2-files, merging
> this together with the code in grib2ctl.pl for grib1 files. Although a
> control file is created, I also get errors like:
>
> grib header at record 1: two values of nxny 246768 144639
>    LEN 162734 DataStart 14 UnusedBits 6 #Bits 9 nxny 246768
>
> When I then go ahead and try to plot a map using GrADS, I always get
> "Entire Grid undefined". I have attached the grib file, the index file
> and the control file.
>
> What am I doing wrong? How can I extract the data from this gribfile?
>
> Thank you for your help!
>
> Best regards,
> Jonas Kaufmann
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