Standards-Based, Web Services for Interoperable Geosciences Data Systems

Disparate, "stove-pipe" data systems are among the main impediments to many interdisciplinary research projects in the geosciences. The solid earth disciplines and hydrology tend to use Geographic Information Systems (GIS) which enable them to store and interact with data representing as discrete features on or near the surface of the earth. Studies of the oceans and atmosphere on the other hand involve systems that represent data as discrete points in the continuous function space of fluid dynamics. Attempts to understand the nature of severe precipitation and flooding events are hampered by the difficulty of integrating data such as streamflows from hydrological data systems with radar data and precipitation forecasts from atmospheric science data systems. An effort is underway to address some of these issues with an interoperability experiment within the framework of the Open Geospatial Consortium (OGC). The experiment is called GALEON (Geo-interface to Atmosphere, Land, Earth, Ocean NetCDF). Teams at the Unidata Program Center and University of Florence are working with a number of international partners to implement a web services interface to traditional atmospheric and oceanographic datasets currently stored in netCDF form or served via the OPeNDAP protocol . The project will result in a gateway service using Web Coverage Service (WCS) specification of the OGC. Underneath the WCS interface will be a combination of technologies including THREDDS (THematic Real-time Environmental Distributed Data Services) and HDF5 (Heirarchical Data Format) in addition to netCDF and OPeNDAP. A key component of the project is to develop mechanisms for explicit encoding of coordinate system information in the form of Coordinate System extensions to NcML (the netCDF Markup Language), directly in the data files themselves and in the form of GML (Geography Markup Language) extensions to NcML. These extensions, called NcML-GML, include a subset profile of the standard GML which is in the late stages of adoption by the International Standards Organization (ISO). The paper presents the current status and updated objectives of the project.