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Access to real-time distributed Earth and Space Science (ESS) information is essential for enabling critical Decision Support Systems (DSS). Thus, data model interoperability between the ESS and DSS communities is a decisive achievement for enabling cyber-infrastructure which aims to serve important societal benefit areas. The ESS community is characterized by a certain heterogeneity, as far as data models are concerned. Recent spatial data infrastructures implement international standards for the data model in order to achieve interoperability and extensibility. This paper presents well-accepted ESS data models, introducing a unified data model called the Common Data Model (CDM). CDM mapping into the corresponding elements of the international standard coverage data model of ISO 19123 is presented and discussed at the abstract level. The mapping of CDM scientific data types to the ISO coverage model is a first step toward interoperability of data systems. This mapping will provide the abstract framework that can be used to unify subsequent efforts to define appropriate conventions along with explicit agreed-upon encoding forms for each data type. As a valuable case in point, the content mapping rules for CDM grid data are discussed addressing a significant example.

One barrier to research at the boundaries of the traditional Earth sciences is a lack of interoperability among data systems employed in the traditional subdisciplines. Solid Earth scientists (including the hydrology community) have tended to view their datasets as descriptions of discrete objects with attributes that can be stored and manipulated conveniently in a database. Geographic Information Systems (GIS) work well in this environment. On the other hand, the oceanographic and atmospheric sciences (the Fluid Earth Sciences or FES) communities think of data as discrete points in a continuous mathematical function space where the behavior of multiple parameters in space and time is governed by a set of equations.In an attempt to bridge the gap between these groups, the GALEON (Geo-interface for Air, Land, Earth, Ocean NetCDF) interoperability experiment is being conducted under the aegis of the Open Geospatial Consortium (OGC). There are two main components of this initiative:A Formal OGC Interoperability Experiment. The objective is to ascertain the suitability of the OGC Web Coverage Service (WCS) interface specification for serving datasets that are typical of those stored in netCDF (network Common Data Form). This will be done in the context of the formal OGC interoperability experiment. About a dozen WCS client and server implementations are involved in this aspect of the experiment. A few of these existed before GALEON; others are being developed in conjunction with the experiment.A WCS Gateway Implementation. The second component is to develop WCS client and server software implementations that will enable the WCS clients to access data via a WCS gateway to existing distributed servers that already serve data in netCDF. This will be done by the netCDF, THREDDS (THematic Realtime Environmental Distributed Data Services), OPeNDAP (Open Project for a Network Data Access Protocol, formerly the Distributed Oceanographic Data System, DODS), LAS (Live Access Server), GDS (GrADS Data Server formerly GrADS Data Server), etc.The primary objectives of formal OGC interoperability experiment are to determine whether: a viable WCS getCapabilities geo-interface (gateway in earlier versions) can be built on existing THREDDS inventory catalog services the ncML-G data model is adequate for providing describeCoverage responses for netCDF datasets there are any solutions to the previously identified limitations to geoTIFF encoding format for representing 5-D netCDF files in such a way that the relationships among layers are preserved the proposed ncML-GML encoding format is a practical solution to serving 5D data from netCDF files, either embedded (ASCII or attached binary) or linked (OPeNDAP link or other URL) netCDF itself is a viable WCS binary encoding format6. existing WCS clients are able to access analyze and display 5D data from netCDF files 7. 5D geospatial data sets can be served efficiently through standard database technology In essence, the second GALEON component is to specify and implement a web services int...

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