Re: DODS access to GDS GRIB files

[James Gallagher <jgallagher@xxxxxxxxxxx>]

On Mon, 2004-02-09 at 10:35, Matt Howard wrote:
> Help,
> 
> I'm trying to use a DODS-enabled version of ferret to access Eta
> weather model output through the NOAA NOMAD servers. My goal is
> to pull down regional subsets of the Eta fields. But right now I'd
> be happy if ferret could read anything from the target file.
> 
> A web browser or the OPeN DAP Data Connector shows that the following
> URL is correct. But ferret complains.
> 
> saltwater> ferret 
>         NOAA/PMEL TMAP
>         FERRET v5.41  
>         IRIX 6.5 - 08/30/02
>          9-Feb-04 11:12     
> 
> yes? use
> http://nomad1.ncep.noaa.gov:9090/dods/eta/archive/eta20040209/eta1hr_00z?vgrd10m.lat[0:1:10]
>  ** netCDF error: Invalid Argument
>  is this a CDF file ?
> 
> The underlying file is probably in GRIB format not netCDF, but DODS
> should be making this transparent to me.
> 
> Any ideas why this access doesn't work. Is there a workaround?

I can get data from the server using a browser. To to that, type the URL
in a browser and insert ".ascii" right before the "?". It looks like:

	http://noma ... 209/eta1hr_00z.ascii?vgrd10m.lat[0:1:10]

The result, in the browser, is: 

lat, [11]
12.0, 12.11, 12.22, 12.33, 12.44, 12.55, 12.66, 12.77, 12.88, 12.99, 13.1

So the server is working. 

To look at the data in Ferret, try opening the data set without a
constraint. You should be able to look all the variables and pick which
ones you want to load. Ferret won't actually read the variables over th
net when you open the data set, it waits until you start asking for
specific ones to read data from the server.

Warning: I'm not a Ferret user, I'm the tech lead for DODS/OPeNDAP.
Caveat Emptor ;-)

James

> Thanks
> 
> Matt 
> 
> +----------------------------------------------------------------------+
> | Dr. Matthew K. Howard                   Voice: (979)-862-4169        |
> | Department of Oceanography                FAX: (979)-847-8879        |
> | Texas A&M University              Internet: mkhoward@tamu.edu        |
> | College Station, TX 77843-3146      webcam: http://seawater.tamu.edu |
> +----------------------------------------------------------------------+
-- 
__________________________________________________________________________
James Gallagher		         The Distributed Oceanographic Data System
jgallagher@gso.uri.edu               http://unidata.ucar.edu/packages/dods
Voice/Fax: 406.723.8663