Access to Thredds and Opendap data

[Jennifer Adams]

You should be using the 'gradsdap' executable to access OPeNDAP
servers. I am able to open one of these data sets with sdfopen. Beware
that there are many more coordinate variables than the usual set, and
to see all the variables you will need to use xdfopen or open with a
descriptor file to map the following to X, Y, Z, T, and E:

netcdf gfs_4_20090109_1800_171 { // format variant: 64bit
dimensions:
         time1 = 1 ;
         pressure1 = 1 ;
         lat = 361 ;
         lon = 720 ;
         pressure = 26 ;
         time = 1 ;
         pressure3 = 21 ;
         pressure_difference_layer1 = 1 ;
         pressure4 = 2 ;
         potential_vorticity_surface = 2 ;
         height_above_ground1 = 1 ;
         pressure2 = 6 ;
         pressure_difference_layer = 1 ;
         depth_below_surface_layer = 4 ;
         altitude_above_msl = 3 ;
         height_above_ground = 1 ;
         bounds_dim = 2 ;


On Jan 11, 2009, at 5:59 AM, James Burn wrote:

> Hi
>
> I'm wondering if it is possible to use Grads 2.0 to access data via an
> Opendap server such as
> http://nomads.ncdc.noaa.gov/thredds/catalog/gfs4/catalog.html
>
> I've not seen any mention of Thredds here on the Grads list so am
> guessing
> its not the done thing. I've Windows XP here and Opensuse Linux at
> home.
>
> When I try to sdfopen one of the Grib2 files eg
> http://nomads.ncdc.noaa.gov/thredds/dodsC/gfs4/200901/20090108/gfs_4_2009010
> 8_1800_171.grb2
>
> I get gaopnc error and "Can't ingest SDF Metadata".
>
> I've also tried making the appropriate .inv and .idx files locally and
> opening a local .ctl file which seems more promising, but seems to
> fall
> over when accessing the binary file via http.
>
> Is what I am trying to do possible? Or is data access limited to
> dods and
> local servers?  My feeling is that I'm missing a trick or two.
>
> This is my first post, although I've been hacking together scripts
> for a
> year now and would like to thank all those who contribute to this
> list for
> the tips I've picked up so far!
>
> Thanks
> James Burn

--
Jennifer M. Adams
IGES/COLA
4041 Powder Mill Road, Suite 302
Calverton, MD 20705
jma at cola.iges.org



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