An interoperability language to connect netCDF and Geographic communities: ncML-GML v. 0.5

NcML-GML is an extension of the netCDF Markup Language (ncML); it enables encoding of netCDF datasets in terms of GML 3.0 elements. It was conceived to facilitate interoperability between the data systems of the atmospheric sciences and the GIS communities. NcML-GML leverages the ncML ability to encode multi-dimensional arrays and the wide acceptance of GML for encoding geo-spatial metadata. Based on GML 3.0 grammar, ncML-GML implements one of the possible encodings of a general interoperability model (i.e. both abstract and content interoperability models) which reconciles typical atmospheric sciences and geo-spatial data models. In this paper we describe the recently released version: ncML- GML ver. 0.5. The main objective of this version was to simplify the encoding process, by reducing the complexity and the number of necessary schemas and stressing the utilisation of GML grammar. The motivation, objectives and the newly-developed schemas are described and discussed. An open issue still remains the choice of the encoding grammar for dataset Coordinate System: presently, they are encoded using the ncML-CS grammar; this choice is presented and discussed. NcML- GML ver. 0.5 will be used in the framework of an interoperability experiment which aims at extending the OGC WCS specification in order to support netCDF datasets. The role played by NcML- GML in this experiment is summarized.