Re: [Fwd: Serving remote NCEP ETA fields via LAS]

[Joe McLean <joe.mclean@xxxxxxxx>]

Hi Matt,

I just tested the data configuration and it works fine for me.  In some of your tests, I think
your DODS cache may have been corrupted.  Try clearing out your DODS cache directory.  In LAS
v6.2 the directory is located at las/server/dods/.dods_cache.

Joe
----------------------------------

Matt Howard wrote:

> 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 |
> +----------------------------------------------------------------------+