Re: Reading 13 km RUC problem

From: David Brown <dbrown_at_nyahnyahspammersnyahnyah>
Date: Mon Nov 09 2009 - 11:50:47 MST

Hi James,
This is just a warning that results from one or a few records in the
GRIB file where the parameter discipline and category are
"missing" (i.e. set to 255) in the GRIB record, and therefore NCL
cannot find an entry in the code tables that describes the parameter.
The record still appears in NCL's view of the file. In a sample RUC2
analysis file that I just downloaded, it looks like this in the
ncl_filedump output:

       float VAR_255_255_255_P0_L200_GLC0 ( ygrid_0, xgrid_0 )
          center : US National Weather Service - NCEP (WMC)
          production_status : Operational products
          long_name : unknown variable name
          units : unknown
          _FillValue : 1e+20
          coordinates : gridlat_0 gridlon_0
          grid_type : Lambert Conformal can be secant or tangent,
conical or bipolar
          parameter_discipline_and_category : Missing, Missing
          parameter_template_discipline_category_number : ( 0, 255,
255, 255 )
          level_type : Entire atmosphere (considered as a single layer)
          level : 0
          forecast_time : 0
          forecast_time_units : hours
          initial_time : 11/09/2009 (00:00)

Looking at the same file with 'wgrib -v2', this data appears as the
very last records and is is decorded as follows:

271:20401422:00Z09nov2009:IMGD Image data [-]:lvl1=0*10**0
lvl2=missing lvl1=(200,0) lvl2=(255,missing):entire atmosphere
(considered as a single layer):anl:

wgrib2 describes data for which there is no entry in the code tables
as: IMGD Image data. Perhaps there is a reason for this but I don't
know what it is. Maybe someone from NCEP can enlighten us on this point.

But the basic point is that NCL is still giving you access to all the
information contained in this file.

On Nov 6, 2009, at 10:01 AM, Means, James wrote:

> Hi, has anyone else tried to read in 13 km RUC analysis files? I get
> the following message:
> ncl 0> f=addfile("ruc2_130_20091013_1600_000.grb2","r")
> warning: NclGRIB2: codetable file "/home/jmeans/ncl/lib/ncarg/
> grib2_codetables/ncep/4/" not a valid GRIB2 code
> table.
> If I convert the grib2 file to NetCDF using the grib2 utility I can
> read in the NetCDF file, but this takes quite a bit of time and the
> file size increases tremendously.
> I'm running NCL 5.1.1.
> Thanks,
> Jim Means
> Scripps Institution of Oceanography, UCSD
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Received on Mon Nov 9 11:50:09 2009

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