Re: 40 KM RUC data

Just to add a bit to what Dennis said:

The message
warning: NclGRIB2: codetable file "/contrib/ncl-5.0.1-beta/lib/ncarg/
grib2_codetables/ncep/4/4.2.255.255.table" not a valid GRIB2 code table.

is only a warning. It does not mean that NCL failed to read the GRIB
file. Admittedly it is somewhat confusing. It means that a GRIB
record was
encountered that has both the product discipline and parameter
category codes set to 255, which stands for "missing". The parameter
number itself
is also set to "missing". There is no code table for "missing"
disciplines and categories, and there never will be. In the case of
your sample file there
is one record that has these values. NCL still makes it available as
VAR_255_255_255_P0_L200_GLC0 with the following attributes:

  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 : -999
          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 : 3
          forecast_time_units : hours
          initial_time : 01/29/2009 (13:00)

This variable is known to be on the same grid as all the variables in
the file, and as you can see, some other information is known as
well. But
NCL has no way to know what the data represents. I am not sure why
some NCEP-generated GRIB2 data includes records like this.
If anyone on the mailing list has knowledge of this, we would be
interested to find out.

The version of wgrib2 that I have does have a table entry that gives
the short name IMGD and the description "Image data" to records that
would give rise to this warning message in NCL. But I do not see this
usage documented anywhere in the NCEP GRIB 2 documentation at:
http://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc.shtml

  -dave

On Jan 29, 2009, at 12:23 PM, Dennis Shea wrote:

> Hi Jeff
>
> This file can be read with NCL both version 5.0.0 and 5.1.0
> However, note the *warning* message.
>
> Also, FYI ...
>
> NCL allows users to input GRIB code tables.
>
>
> %> ncl_filedump fh.0003_tl.press_gr.us40km.grb
>
> Copyright (C) 1995-2009 - All Rights Reserved
> University Corporation for Atmospheric Research
> NCAR Command Language Version 5.1.0 [same
> for 5.0.0]
> The use of this software is governed by a License Agreement.
> See http://www.ncl.ucar.edu/ for more details.
>
> warning: NclGRIB2: codetable file "/contrib/ncl-5.0.1-beta/lib/
> ncarg/grib2_codetables/ncep/4/4.2.255.255.ta
> ble" not a valid GRIB2 code table.
>
> Variable: f (file variable)
> filename: fh.0003_tl.press_gr.us40km
> path: fh.0003_tl.press_gr.us40km
> file global attributes:
> dimensions:
> ygrid_0 = 113
> xgrid_0 = 151
> lv_ISBL0 = 37
> lv_SPDL1 = 6
> lv_HTGL2 = 2
> variables:
> float TMP_P0_L1_GLC0 ( ygrid_0, xgrid_0 )
> center : US National Weather Service - NCEP (WMC)
> production_status : Operational products
> long_name : Temperature
> units : K
> _FillValue : -999
> coordinates : gridlat_0 gridlon_0
> grid_type : Lambert Conformal can be secant or tangent,
> conical or bipolar
> parameter_discipline_and_category : Meteorological
> products, Temperature
> parameter_template_discipline_category_number : ( 0,
> 0, 0, 0 )
> level_type : Ground or water surface
> level : 0
> forecast_time : 3
> forecast_time_units : hours
> initial_time : 01/29/2009 (13:00)
>
> [SNIP]
> float gridrot_0 ( ygrid_0, xgrid_0 )
> long_name : vector rotation angle
> GridType : Lambert Conformal (secant, tangent, conical
> or bipolar)
> units : radians
> formula_u : Uearth = sin(rot)*Vgrid + cos(rot)*Ugrid
> formula_v : Vearth = cos(rot)*Vgrid - sin(rot)*Ugrid
> note1 : u and v components of vector quantities are
> resolved relative to grid
> note2 : apply formulas to derive u and v components
> relative to earth
>
> float gridlat_0 ( ygrid_0, xgrid_0 )
> corners : ( 16.281, 17.34025, 55.48128, 54.17237 )
> long_name : latitude
> grid_type : Lambert Conformal (secant, tangent, conical
> or bipolar)
> units : degrees_north
> Latin2 : 25
> Latin1 : 25
> Dy : 40.635
> Dx : 40.635
> Lov : 265
> Lo1 : 233.862
> La1 : 16.281
>
> float gridlon_0 ( ygrid_0, xgrid_0 )
> corners : ( -126.138, -69.03806, -57.38121, -139.8561 )
> long_name : longitude
> grid_type : Lambert Conformal (secant, tangent, conical
> or bipolar)
> units : degrees_east
> Latin2 : 25
> Latin1 : 25
> Dy : 40.635
> Dx : 40.635
> Lov : 265
> Lo1 : 233.862
> La1 : 16.281
>
>
>
> Copes, Jeff wrote:
>>
>> All,
>>
>> I am not able to decode a 40 KM RUC data GRIB2 file with NCL. The
>> NetCDF Java decoder is able to handle the file, as well as wgrib2,
>> but not the NCL. The GRIB2 code table mentioned below,
>> 4.2.255.255.table, does not exist in any directory. I am not sure
>> why the path to the file is incorrect, but, as a temporary debug
>> workaround, created a link in the code table directory to "/
>> programs" to allow for the path to be valid.
>>
>> jcopes(193):/programs/ssa/jcopes/ncarg/bin/ncl_convert2nc /
>> programs/public/yogin/fh.0003_tl.press_gr.us40km.grb
>> Processing file: fh.0003_tl.press_gr.us40km.grb...
>> Copyright (C) 1995-2007 - All Rights Reserved
>> University Corporation for Atmospheric Research
>> NCAR Command Language Version 5.0.0
>> The use of this software is governed by a License Agreement.
>> See _http://www.ncl.ucar.edu/_ for more details.
>> warning: NclGRIB2: codetable file "/programs/ssa/jcopes/ncarg/lib/
>> ncarg/grib2_codetables//programs/ssa/jcopes/ncarg/lib/ncarg/
>> grib2_codetables/ncep/4/4.2.255.255.table" not a valid GRIB2 code
>> table.
>>
>>
>> jcopes(195):ls -l /programs/public/yogin/fh.
>> 0003_tl.press_gr.us40km.nc
>> -rwxrwxrwx 1 jcopes users 0 Jan 29 17:25 /programs/public/yogin/
>> fh.0003_tl.press_gr.us40km.nc*
>>
>> If possible, I would like to resolve the incorrect path issue also.
>>
>> Thanks,
>>
>> Jeff Copes
>> Weather Research and Development
>> Harris Corporation
>> Melbourne, Florida
>> 321.309.7856
>>
>> ---------------------------------------------------------------------
>> ---
>>
>> _______________________________________________
>> ncl-talk mailing list
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>>
>
>
> --
> ======================================================
> Dennis J. Shea tel: 303-497-1361 |
> P.O. Box 3000 fax: 303-497-1333 |
> Climate Analysis Section |
> Climate & Global Dynamics Div. |
> National Center for Atmospheric Research |
> Boulder, CO 80307 |
> USA email: shea 'at' ucar.edu |
> ======================================================
>
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Received on Thu Jan 29 2009 - 16:03:53 MST