Re: NCL and Grib Files with Second Order Packing

From: David Brown <dbrown_at_nyahnyahspammersnyahnyah>
Date: Fri Mar 01 2013 - 12:46:35 MST

Hi James,
Second order unpacking has not been implemented because we have never had any test files with second order packing.

If you can make some representative samples available to us either by uploading the files using the instructions at or by instructing me how to download the files myself if they are publicly accessible
then we can hopefully make time to implement 2nd order unpacking before the next release. Are these GRIB1 or GRIB2 files?
Let me know offline the names of the files you upload. Thanks.

On Mar 1, 2013, at 7:09 AM, James Belanger wrote:

> NCL community,
> I'm using NCL Version 6.0 and am having an issue extracting data from
> grib (v1) files that ECMWF sends us in real-time that feature second
> order packing (significantly reduces file size). While I am able to
> use addfile and can view the variables with a print statement with
> NCL, when I try to extract any of the variables, I receive a
> segmentation fault error. I've traced the issue to the way the grib
> files have been packed --> if I repack the files using ECMWF's grib
> API from second order to simple packing, I have no problems extracting
> the data. I checked the NCL archive and from my cursory look haven't
> found this issue reported before.
> At this time, the work around I've adopted is to repack the grib files
> before using NCL to extract and manipulate the data. However, it
> would be nice if future versions did not require this work around. I
> also wasn't sure if maybe this issue had been addressed in a later
> update since I'm not using the latest version.
> Thoughts and/or suggestions?
> Thanks,
> James
> --
> James Belanger, Ph.D.
> Research Scientist II
> School of Earth and Atmospheric Sciences
> Georgia Institute of Technology
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Received on Fri Mar 1 12:46:45 2013

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