GALEON Progress Update

Ben Domenico, April 2009


One of the primary objectives of GALEON (Geo-interface to Air, Land, Earth, Ocean netCDF) is to establish standards-based protocols through which other communities can access datasets provided via Unidata technologies.?? Interactions with the Unidata 2013 review panel clarified that this allows Unidata to make data available to other groups (e.g., hydrology, societal impacts, hazards) without supplying the complete end-to-end support of analysis and display client applications as we do for our core user community.? One of the best examples of this is the GIS user community which uses the ESRI ArcGIS tools for the most part.? Given ESRI native support for netCDF files and for the Web Coverage Service (WCS) protocol of the Open Geospatial Consortium (OGC), ArcGIS users can obtain our data via WCS and use the ESRI analysis and display tools of ArcGIS.? The IDL package from ITTvis is another example of a client application that can access netCDF data via WCS for analysis and display.? By influencing and supporting such international standard protocols, Unidata can serve data to these other groups without having to support their analysis and display applications.

The approach we are taking with the GALEON ?project is to establish a standards-based (Open Geospatial Consortium Web Coverage Service) interface to the THREDDS Data Server which includes THREDDS, netCDF, OPeNDAP services. Background documents are available:

 Phase 1

The most important development of GALEON Phase 1 has been acceptance of the approach we've proposed for revising the binary encodings section of the WCS 1.1 specification.  The proposed changes make CF-netCDF one of the supported encoding formats.  The essence of the changes is provided in two documents.  The first summarizes the revised section of the spec itself:

and the second is the draft WCS 1.1 application profile for encoding CF-netCDF.

Phase 2

Last year, GALEON entered Phase 2.? Since that time, the GALEON wiki has been transferred to Google sites at:

GALEON Phase 2 objectives center on

  • implementing and testing WCS 1.1 clients and servers
  • determining the relationships among alternative interfaces for delivering netCDF datasets (e.g. WFS or SOS)
  • experimenting with other scientific data types (e.g. point/station observations, swath, radar radial, trajectory, etc.)
  • incorporating OGC CS/W catalog services and a gateway to underlying THREDDS catalog services.
  • GML issues related to ncML-GML, CSML, and perhaps GMPJPEG2000

GALEON Use Cases Extended to Non-gridded Datasets

As noted earlier, GALEON has focused on serving gridded datasets via the WCS interface to this point.? But the time has come to address the issue of how the many collections of non-gridded data should be served via standard interfaces.? The non-gridded collections include:

  • point data from lightning strike observations
  • "station" observations from fixed weather stations
  • vertical profiles from balloon soundings and wind profilers
  • trajectory data obtained from instruments onboard aircraft which have taken off and landed recently
  • volumetric scans from ground-based radars
  • visible, infrared, and water-vapor (and possibly other wavelength) satellite imagery 
  • gridded output from national or hemispheric weather forecasts (typically run at centers like NCEP and ECMWF) --sometimes used as boundary conditions for a higher-resolution local forecast model.


A set of use cases for such collections is being developed at:

OGC Technical Committee

As the official UCAR representative to the OGC Technical Committee, Unidata participates in 3-4 technical committee meetings per year to ensure that Unidata and UCAR needs are met in the emerging international standards. In recent weeks, there have been many areas of OGC activity related to GALEON.  This note is an attempt to outline highlights of the areas of interest and provide pointers to more detailed information.

At the OGC Technical Committee (TC) meeting (Mar 30 - Apr 2):
Stefano's presentation on the CF-netCDF and OPeNDAP Extension to WCS is available at: 0

At the TC meeting and in WCS SWG telecons before and after, several additional topics of interest to GALEON are under discussion:
  • multiple time dimensions (e.g., forecast model run time, and forecast time)
  • parameterized dimention (e.g., pressure as a vertical dimension)
  • uneven grid point spacing (including conversions back and forth to index space)
  • continuous coverages with non-geometric interpolations   
Related to those important issues, two key ISO specification documents are under revision and extension at this point, so there is an opportunity to influence those ISO specifications as well as those of OGC: 
As these discussions coalesce, I will attempt to summarize the important ones on the GALEON wiki and forward relevant OGC email discussions to the GALEON email list.

NASA ACCESS-geosciences CAN Project (originally GOLAC)

A joint proposal to the NASA ACCESS CAN by Liping Di of George Mason as PI with Unidata and NCDC as the main collaborating institutions. This proposal, originally entitled GOLAC (Gateway for Interoperability of Atmosphere, Land, Ocean, and Modeling Science Data) was successful but in an unusual sort of way. The GOLAC team was instructed to combine its proposed project with another proposal led by Ken McDonald of NASA Goddard.

The final step, completed in December 2008, was to experiment with the GMU server using the GIGO and ArcGIS clients.? The ArcGIS client is part of the 9.3 release whose beta is to be available to UCAR shortly.? GIGO is a standards-based client of both CSW and WCS. A draft of the final report for the overall project is available at:

A draft tech note covering the CSW catalog services and THREDDS catalogues is at:

KNMI Atmospheric Data for the GIS User Community (ADAGUC) Project

The final workshop was held in December 2008.? The summary and presentations are at:


Follow up collaborations with the KNMI group are being discussed on IDV, THREDDS, and GALEON.? KNMI sent several representatives to the NCAR GIS workshop and to the Unidata training workshops.

Final THREDDS Second Generation Survey and Project Closeout

The THREDDS Second Generation final evaluation survey was completed and the final project report submitted to NSF in December 2008.? The final survey results are given in:

AccessData (formerly DLESE Data Services) Workshops 

Continue Unidata hosted last year?s workshop and is participating in this year?s workshop in early June.? The overall program is described at:

and this year?s workshop page is:

Proposals and Other Collaborations:

  • Possible NASA ROSES with Ed and Others (Unidata in lead)<
  • Olga?s initiative with CUAHSI and NEON (formerly known as CoAHP)<
  • NSF DataNet Datapedia proposal with John Helly at UCSD
  • Water Cycle proposal with Chris Duffy of Penn State and CUAHSI<
  • WMS for Met data with Jon Blower of UK Met Office
  • MBARI ontology related proposal with John Graybeal and Carlos Rueda
  • Working with other Unidata staff members, dontinue leadership role in AGU and EGU Earth and Space Science Informatics groups
  • Participant in NCAR GIS project
  • Member of CUAHSI Hydrological Information System Steering Team
  • Member of Integrated Ocean Observing System Data Management Committee (DMAC)
  • Member of the Marine Metadata Interoperability (MMI) project Steering Team
  • Sponsoring member of the OGC Ocean Sciences Interoperability Experiment
  • WCS Python Client Experiments with British Atmospheric Data Center