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[GEMPAK #DKW-494657]: GEMPAK GRIB Bug?

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  • Subject: [GEMPAK #DKW-494657]: GEMPAK GRIB Bug?
  • Date: Thu, 15 May 2008 05:13:42 -0600
Hi Brent-

NCEP reports that this bug is fixed in their current release of
GEMPAK.  The next release from Unidata will include that fix, but
we don't have a timeline for that at this point.

Don Murray

> I have searched the GEMBUD and GEMPAK support lists and have not found
> this reported by anyone else, but it seems that NAWIPS/GEMPAK has an
> issue with GRIB records where the decoded values should be an entire
> grid of zeros (as sometimes happens with precipitation and hydrometeor
> fields in limited area mesoscale models).  I have found this problem
> using a Linux build of NAWIPS/GEMPAK that I have built from source
> using g77 and gcc.  I have found it to be a problem on both 32-bit
> Linux and 64-bit Linux (RedHat in both cases).  Here is a detailed
> description of what I did and observed:
> 
> 
> 1. GRIB edition 1 files (created by the NCEP-developed WRF
> post-processor) are decoded with dcgrib2 as follows:
> dcgrib2 myfile.gem < myfile.grb
> 
> 2. Rendered the total precipitation forecast from the resulting
> GEMPAK file and find a corrupted, noisy image that changes
> patterns each time I hit reload.  Additionally, the rendering
> generates the following error in the Error status window:
> 
> [DG2] Too many maxs found -- increase radius or reduce range
> 
> 1. Ran the GEMPAK file through "gdlist" to see min/max values actually
> contained in the GEMPAK file.  It reports a combination of zeros,
> 10.0s, 20.0s, and 30.0s.
> 
> 2. Ran the original GRIB file through wgrib and IDV and verified the
> original GRIB field is encoded correctly and that all grid points
> actually are 0.
> 
> The attached tar ball has the original GRIB record, the resulting
> GEMPAK file created from dcgrib2, and the sample NAWIPS image
> demonstrating the problem.
> 
> Thanks for your help in advance!  Please let me know if you need
> anything else from me.
> 
> Best regards,
> 
> Brent
> 
> Brent Shaw
> Senior Meteorologist and Project Manager
> [cid:image002.gif@01C8AF63.F69F0960]
> Weather Decision Technologies Inc<http://www.wdtinc.com/>.
> 3100 Monitor Ave.
> Norman, OK 73072
> Office:  (405) 579-7675 x246
> Mobile: (405) 397-9950
> 
> 
> 


Ticket Details
===================
Ticket ID: DKW-494657
Department: Support GEMPAK
Priority: Normal
Status: Open