[Fwd: Serving remote NCEP ETA fields via LAS]

[Matt Howard <mkhoward@xxxxxxxx>]

Dear Joe,

Thanks for the suggestion, however it fails in LAS with the following error.

 The following error message was received from LAS:

Adding an acceptable error string: "*** NOTE: ".
        NOAA/PMEL TMAP
        FERRET v5.53  
        IRIX 6.5 - 10/06/03
         4-Mar-04 11:50     

yes? cancel mode verify
yes? cancel mode interp
yes? canc data/all
yes? go std_initialize
"http://nomad1.ncep.noaa.gov:9090/dods/eta/archive/eta20040304/eta1hr_00z"; "1"
"1" "vgrd10m"
 ** netCDF error: Invalid Argument
 is this a CDF file ?
set data
"http://nomad1.ncep.noaa.gov:9090/dods/eta/archive/eta20040304/eta1hr_00z";
Command file, command group, or REPEAT execution aborted

Help,

Matt
-------------------------------------------------------------------


Joe McLean wrote:
> 
> Hi Matt,
> The url syntax for the LAS XML dataset configuration  is as follows.
> under the dataset element
> url="http://nomad1.ncep.noaa.gov:9090/dods/eta/archive/eta20040304/eta1hr_00z";
> 
> under the variable element
> url="http://nomad1.ncep.noaa.gov:9090/dods/eta/archive/eta20040304/eta1hr_00z";
> 
> or
> url="http://nomad1.ncep.noaa.gov:9090/dods/eta/archive/eta20040304/eta1hr_00z#vgrd10m";
> 
> 
> 
> The url under the dataset element does not need a variable specific syntax
> and, in fact, LAS will not know how to process the # syntax.
> LAS associates the dataset URL with the variable requested and uses the
> element tag ('vgrd10m') as the variable to access.  When a 'virtual dataset'
> is incorporated into LAS, different variable elements under the same dataset
> element may have different URL's. In these cases the URL under the variable
> element over-rides the dataset URL.   Either the variable element tag
> (vgrd10m) is used to access the data or the var_name in #var_name when the #
> syntax is iuncluded.
> 
> I think what you want to use is the simplest form:
> 
> <!-- Define datasets/variables -->
>    <datasets>
>     <eta12 name="Eta-12 V winds at 10m"
> 
> url="http://nomad1.ncep.noaa.gov:9090/dods/eta/archive/eta20040304/eta1hr_00z";>
> 
>      <variables>
>       <vgrd10m name="North winds at 10m" units="Meters/sec">
>        <link match="/lasdata/grids/eta12_grid"/>
>       </vgrd10m>
>      </variables>
>      </eta12>
>    </datasets>
> 
> 
> Joe
> ------------------------------------------
> 
> Matt Howard wrote:
> 
> > Hi all,
> >
> > I'd like to access and serve NCEP ETA-12 numerical weather model forecast
> > fields.
> >
> > ( These fields are updated frequently, and the file name is based on the
> > date.
> >   So if you are reading this in the near future you may need to modify the
> >   urls given below to point to current output and follow along. So below
> >   eta20040304 is etaYYYYMMDD and you may have to use a current YYYY,MM,DD
> >   to point to an existing file if you want to follow along with this
> > question.)
> >
> > Here is a url to the output. These fields are served using a GDS at NCEP.
> > http://nomad1.ncep.noaa.gov:9090/dods/eta/archive/eta20040304
> >
> > I'd like to serve the hourly fields (eta1hr_00z).  You may see that there
> > are
> > many parameters inside this data set. One in particular is vgrd10m which is
> > North-South winds at 10m altitude.
> >
> > I really only want a regional subset - but for now I'll take all of the
> > values
> > on the [1:500][1:700] grid at 37 different hours.
> >
> > My question centers on how to properly specify the single parameter vgrd10m.
> >
> > The # on the url line is used in some examples, while a ? is sometimes used
> > in other examples of DODS urls. Neither works by the way.
> >
> > Ferret seems happy with using the following (with a ? in the constraint).
> >
> > "http://nomad1.ncep.noaa.gov:9090/dods/eta/archive/eta20040304/eta1hr_00z?vgrd10m";
> >
> > But LAS complains asking "is this a cdf" file. I think the ETA fields start
> > out
> > as GRIB files which is something at GrADS-DODS Server is able to serve.
> >
> > Anyway, here is the xml fragment that I include in las.xml.  The interface
> > builds
> > ok but LAS isn't happy.
> >
> > I appreciate any help or insite you may have.
> >
> > <!-- Define datasets/variables -->
> >    <datasets>
> >     <eta12 name="Eta-12 V winds at 10m"
> > url="http://nomad1.ncep.noaa.gov:9090/dods/eta/archive/eta20040304/eta1hr_00z#vgrd10m";>
> >
> >      <variables>
> >       <vgrd10m name="North winds at 10m" units="Meters/sec">
> >        <link match="/lasdata/grids/eta12_grid"/>
> >       </vgrd10m>
> >      </variables>
> >      </eta12>
> >    </datasets>
> > <!-- Define grids -->
> >    <grids>
> >     <eta12_grid>
> >      <link match="/lasdata/axes/eta12_x"/>
> >      <link match="/lasdata/axes/eta12_y"/>
> >      <link match="/lasdata/axes/eta12_t"/>
> >     </eta12_grid>
> >    </grids>
> > <!-- Define axes -->
> >    <axes>
> >     <eta12_x type="x" units="degrees_east">
> >      <arange start="-140.0" step="0.11" size="700"/>
> >     </eta12_x>
> >     <eta12_y type="y" units="degrees_north">
> >      <arange start="12.0" step="0.11" size="500"/>
> >     </eta12_y>
> >     <eta12_t type="t" units="hour">
> >      <arange start="2004-03-04 00:00:00" step="1" size="37"/>
> >     </eta12_t>
> >    </axes>
> > +----------------------------------------------------------------------+
> > | 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 |
> > +----------------------------------------------------------------------+

-- 
+----------------------------------------------------------------------+
| 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 |
+----------------------------------------------------------------------+