GALEON-related Services

Real-time weather forecast model output datasets
for use in GALEON and other web services experiments.

Ben Domenico
July 26, 2006
<<At the moment, this document is simply a draft illustrating how the wiki can be used>>

One good place to find a substantial collection of datasets of the type that provide a challenge in the GALEON experiment is: Real time weather forecast model data from the Unidata IDD (Internet Data Distribution): http://motherlode.ucar.edu:8080/thredds/idd/models.html

This page points to catalogs of datasets that contain the output of several different weather forecast models run at the National Centers for Environmental Prediction (NCEP). By drilling down into these catalogs of catalogs, one can get a list of datasets corresponding to recent forecast model runs. For example, at the time this page was constructed, the most recent 5-degree Global Forecast Systerm (GFS) dataset was from the 06:00 run on July 26, 2006. The following URL points to the information for that dataset.

http://motherlode.ucar.edu:8080/thredds/catalog/model/NCEP/GFS/Global_0p5deg/catalog.html?dataset=NCEP/GFS/Global_0p5deg/GFS_Global_0p5deg_20060726_0600.grib2

If you replace the string 20060726 with today's date, you'll be able to get a page of information about the model output that includes four different access options:

Access:

OPENDAP: http://motherlode.ucar.edu:8080/thredds/dodsC/model/NCEP/GFS/Global_0p5deg/GFS_Global_0p5deg_20060726_0600.grib2.html

HTTPServer: http://motherlode.ucar.edu:8080/thredds/fileServer/model/NCEP/GFS/Global_0p5deg/GFS_Global_0p5deg_20060726_0600.grib2

WCS: http://motherlode.ucar.edu:8080/thredds/wcs/model/NCEP/GFS/Global_0p5deg/GFS_Global_0p5deg_20060726_0600.grib2?request=GetCapabilities&version=1.0.0&service=WCS

NetcdfServer: http://motherlode.ucar.edu:8080/thredds/ncServer/model/NCEP/GFS/Global_0p5deg/GFS_Global_0p5deg_20060726_0600.grib2?showForm

Here again, these specific URLs point to datasets available at the time this page was create. To get at the current equivalent datasets, replace the date-time string 20060726_0600.

In the access list above, OPENDAP returns the dataset via the OPeNDAP protocol, HTTPserver uses the HTTP protocol and the WCS option returns the WCS capabilities document in XML. On the other hand, the NetcdfServer option brings up a page that allows you to specify a geographic and temporal box and a set of fields. The server will then return a CF-netCDF file that you can store on your local disk. In both cases, the THREDDS Data Server (TDS) underneath it all is taking care of the necessary conversions from the native grib2 format of the NCEP model output. The NetcdfServer option allows the user to learn about what fields are available.