Building an Open Data Portal for the European Space Agency Climate Change Initiative based on an Iterative Development Methodology and Linked Data Technologies

The Climate Change Initiative (CCI) programme was initiated by the European Space Agency (ESA) in 2009 to address the GCOS Essential Climate Variable (ECV) requirements to provide stable, long-term, satellite-based data products to characterise the climate system and its changes. CEDA, working as part of a project consortium, were awarded the contract to build the Open Data Portal, consisting collectively of a central archive and single point of access for dissemination of the data to the international user community. Reflecting climate and earth observation community requirements, the system needed to support a range of access services in use by this domain and specifically, to integrate into existing infrastructure in the form of the Earth System Grid Federation (ESGF). This range of requirements together with the heterogeneity of the ECV datasets presented significant challenges. However, the use of Linked Data technologies and an iterative approach to data model development and data publishing have been instrumental in meeting the objectives and building a cohesive system. The portal supports data discovery based on the OGC CSW specification and on ESGF's powerful faceted search. These services provide complementary content at different levels of granularity and it therefore became clear that a common data model was needed. Key terms are defined in vocabularies serialised in SKOS and OWL and are accessible from a central vocabulary server to provide a single authoritative source for applications consuming metadata content. Exploiting the vocabulary service therefore, it has been possible to develop an innovative solution tagging ISO 19115 records for the CSW with the equivalent vocabulary terms used for the ESGF faceted search system. In this way it has been possible to create a rich user interface for the portal combining search results from both search services and the ability to dynamically populate facet selection and context-based help information from the vocabulary service.