Re: Can't read NCEP NAM12 Grib2 files

From: Ron Chapman <Ron.Chapman_at_nyahnyahspammersnyahnyah>
Date: Mon, 30 Mar 2009 14:53:15 -0400

I tried using ncl_filedump on file that you mentioned
(nam.t00z.awip1203.tm00.grib2). Results are below...

[rjc_at_master nam_test]$ ncl_filedump nam.t00z.awip1203.tm00.grib2
         
Copyright (C) 1995-2009 - All Rights Reserved
 University Corporation for Atmospheric Research
 NCAR Command Language Version 5.1.0
 The use of this software is governed by a License Agreement.
 See http://www.ncl.ucar.edu/ for more details.
Variable: f (file variable)

filename: nam.t00z.awip1203.tm00
path: nam.t00z.awip1203.tm00.grib2
   file global attributes:
   dimensions:
   variables:

I also tried nam.t00z.awphys03.grb2.tm00 and got the same results.

When I modified the ncl script to use addfile (instead of addfiles)
doesn't seg fault, however not sure how to read the grib variables
without addfiles. I'm wondering if this may be a ncl/grib2
configuration issue on our side???

Ron

>>> David Brown <dbrown_at_ucar.edu> 3/30/2009 12:33 PM >>>
Hi Ron,

I tried reading a sample file (nam.t00z.awip1203.tm00.grib2) that I
got from the site you mention and the output looked pretty normal.
(There were a few parameter codes that were unrecognized, but in
general the variables and grids looked reasonable.)

Your sample code below uses 'addfiles'. Do you have the same problem
if you just read one file? Are you saying that when you
do an 'ncl_filedump' it does not produce any content in the file.

Perhaps you could tell me specifically which files you are trying to
use with your sample code.
Thanks,
  -dave

On Mar 30, 2009, at 12:15 PM, Ron Chapman wrote:

> We are having difficulty reading NCEP NAM12 grib2 files from the
NOAA
> ftp site. The actual grib files are the NAM 218 AWIPS Grid - CONUS
> (12-km Resolution) found at the link
> http://www.nco.ncep.noaa.gov/pmb/products/nam
>
> The output from ncl_dumpfile is
>
> $ ncl_filedump nam.grib
> Copyright (C) 1995-2009 - All Rights Reserved
> University Corporation for Atmospheric Research
> NCAR Command Language Version 5.1.0
> The use of this software is governed by a License Agreement.
> See http://www.ncl.ucar.edu/ for more details.
> Variable: f (file variable)
>
> filename: nam
> path: nam.grib
> file global attributes:
> dimensions:
> variables:
>
> when I try and read the grib file with the following ncl script I
> get a
> segmentation fault.
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
>
> begin
>
> diri = "./nam_dynamic/" ; input data directory
> setfileoption("grb","SingleElementDimensions","Forecast_time" )
> fils = systemfunc("cd "+diri +" ; ls DOWNLOAD*.grib")
> f = addfiles (diri+fils, "r")
> end
>
> Any suggestions??
>
>
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Received on Mon Mar 30 2009 - 12:53:15 MDT

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