The development and interlinkage of a drought vocabulary in the EuroGEOSS interoperable catalogue infrastructure

Metadata catalogues are used for facilitating the discovery of data and web services in, e.g., growing collections of Earth observation resources. Two conditions need to be met in order to successfully retrieve resources in catalogues: the metadata describing resources have to be complete and accurate and the keywords used in searches semantically related to the keywords contained in the metadata descriptions. One method to increase the rate of successfully retrieved metadata in catalogues is the use of controlled vocabularies. Such vocabularies can be used for annotating metadata with appropriate keywords and then also presented to users of the catalogue for specifying search terms. In the process of preparing metadata for drought-related data and services within the EuroGEOSS project, the need of a drought-specific vocabulary arose. This paper presents this drought vocabulary, the methodology followed for its development, its integration in the EuroGEOSS drought infrastructure and discusses its usefulness for the drought thematic area. The usefulness of the vocabulary is hereby measured by an increased use of search terms coming from an appropriate vocabulary and by an increase in the successful retrieval of resources. In particular, metadata must be annotated with appropriate keywords from a controlled vocabulary, thesaurus or ontology suitable for that particular field