Re: 20040506: netCDF Decoders - Sun UNIX - CDLs

• To: Beth Hall <bhall@xxxxxxx>
• Subject: Re: 20040506: netCDF Decoders - Sun UNIX - CDLs
• From: Robb Kambic <rkambic@xxxxxxxxxxxxxxxx>
• Date: Mon, 24 May 2004 15:37:07 -0600 (MDT)

On Fri, 21 May 2004, Beth Hall wrote:

Robb --

Thanks for the advice on the CDL's.  You mentioned how to use most of the
CDL's except for the gfs_211.cdl.  This one is of most interest to me
since it seems to be for a much higher resolution (80 km) than the others
and still shows the forecast data.  However, I'm having a hard time
knowing what the actual lat/lon coordinates are for this 80 km grid.  Is

Beth,

The coordinates are constant.

Lat/lon values of the corners of the grid
(1,1)   12.190N, 133.459W
(1,65)  54.536N, 152.856W
(93,65)         57.290N, 49.385W
(93,1)  14.335N, 65.091W

Here's the basic info on all the grids at:

http://www.nco.ncep.noaa.gov/pmb/docs/on388/tableb.html

Actually http://www.nco.ncep.noaa.gov/pmb/docs/on388 give the details of
parameters, etc too.

Other info:

http://www.nco.ncep.noaa.gov/pmb/docs/headers/awpgfs/#TABLEGP


Robb....

this, perhaps a separate file that would specify this information, for I
don't think I need it for every dataset I want to use -- it should stay
fairly constant, right??

Thanks,
Beth Hall

On Fri, 7 May 2004, Robb Kambic wrote:

> On Thu, 6 May 2004, Unidata Support wrote:
>
> >
> > ------- Forwarded Message
> >
> > >To: support-decoders@xxxxxxxxxxxxxxxx
> > >From: "Beth Hall" <bhall@xxxxxxx>
> > >Subject: netCDF Decoders - Sun UNIX - CDLs
> > >Organization: DRI
> > >Keywords: 200405070023.i470NhxJ020678 netCDF decoders gribtonc CDL
> >
> > Institution: Desert Research Insitute
> > Package Version: decoders-3.0.3
> > Operating System: Sun UNIX
> > Hardware Information: Sun
> > Inquiry: I'm trying to access data from the ldm feed, partiticularly
> > the GFS data.  I feel very lost, but finally found the gribtonc
> > command.  I originally used the gfs_211.cdl file, but it gave me no
> > lat/lon coordinates, just x and y.
>
> Beth,
>
> No lat/lon are given because of rounding errors, no accurate values. The
> lat/lon are mainly for human information.
>
>
>
> With this cdl, the ncdump -h said
> > there were 21 records (I'm assuming this refers to the forecasts,
> > themselves).
>
> Your correct the records are for forcast times:
>
>  valtime_offset = 0, 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72, 78,
> 84, 90, 96, 102, 108, 114, 120 ;
>
>
>  I did some web searching and found that there were other
> > CDLs including a 1 degree CDL.
>
> The 1 degree grids are only on the CONDUIT feed, not the standard NOAAPORT
> feed.
>
>
>   I tried it along with the
> > gfs_21-24.cdl, gfs_25-26.cdl, and the gfs_37-44.cdl.  Several of those
> > actually have the lat/lon coordinate information, but now show 0
> > records (no forecast data?).
>
> Maybe you don't have the correct pqact entries, here's the ones we are
> using. Remember the white spaces are tabs between the parts of the
> entries.
>
> # GFS model on global 5.0 x 2.5 degree grids
> HRS     ^H.[A-D]... .... (..)(..).*/m(SPEC62MRF|MRF)
>         PIPE    /usr/local/ldm/decoders/gribtonc
>         etc/gfs_21-24.cdl
>         data/pub/decoded/netcdf/GRIB/(\1:yyyy)(\1:mm)\1\2_gfs_21-24.nc
>
> # GFS model on global 5.0 x 5.0 degree grid
> HRS     ^H.[EF]... KWB. (..)(..)
>         PIPE    /usr/local/ldm/decoders/gribtonc
>         etc/gfs_25-26.cdl
>         data/pub/decoded/netcdf/GRIB/(\1:yyyy)(\1:mm)\1\2_gfs_25-26.nc
>
>
> # GFS model on thinned grids, interpolated to global 5.0 x 2.5 regular
> grid
> HRS     ^H.[I-P]... KWB. (..)(..).*(/mAVN|/mSSIAVN)
>         PIPE    /usr/local/ldm/decoders/gribtonc
>         -q "lin,dlat=2.5,dlon=5.0" etc/gfs_37-44.cdl
>         data/pub/decoded/netcdf/GRIB/(\1:yyyy)(\1:mm)\1\2_gfs_37-44.nc
>
> I know the data must be there, but clearly
> > don't understand what these different CDLs are doing, which one I
>
> The cdl file are templates for making the NetCDF files, the number
> designation at the end of the cdl refers to the grib sections ie 21-24
> that are stitched together to form the whole grib file.
>
> Robb...
>
> > should use, and which ones give me the lat/lon coordinate information.
> > Can you help?  Thanks.
> >
> > --
> > NOTE: All email exchanges with Unidata User Support are recorded in the
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> > ------- End of Forwarded Message
> >

==============================================================================
Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
rkambic@xxxxxxxxxxxxxxxx                   WWW: http://www.unidata.ucar.edu/
==============================================================================