Global Drought Monitoring Service through the GEOSS Architecture ...

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Architectural Implementation Pilot, Phase 3 Version: 2.0 Global Drought Monitoring and European Drought Observatory-Water SBA Engineering Report Date: 11/Feb/2011 submits the queries to the EuroGEOSS Broker Use Case: Discovery: Client Search of Metadata Step 03.2: The EuroGEOSS Broker mediates the query request, distributing it to its federated services Step 03.3: The Decision maker uses the Decision Support System to select one or more drought hazard related information datasets, among the ones returned by the query Presentation of Reachable Services and Alerts Step 03.4: The Decision Support Tool submits an access request to the EuroGEOSS Broker in order to retrieve the user-selected drought hazard information datasets Interact with Services Step 04: Visualization and Assessment of Information Step 04.1: The Decision Support Tool displays the accessed drought hazard information datasets, combining them with the potential hazard layer Step 04.2: The decision maker assesses the drought hazard impact 5.2.1 Advanced Semantic Search Scenario Step 03 embodies the advanced semantics incorporated into the European Drought Implementation. Upon being notified of a drought alert in an area of interest, the decision maker (drought expert) can go online to consult the common EuroGEOSS broker-EDO interface. For example, the EuroGEOSS broker incorporates both: 1) Discovery Augmentation Component (DAC) and 2) the workflow engine, which increases the power of search by integrating together catalogue and semantic components. In other words, the workflow engine browses the semantic repositories to retrieve concepts. Once the expert drought user has identified a concept of interest, the resources (datasets and services) linked to each of these concepts can be retrieved. 5.2.1.1 Ontology Registration An ontology is a technology for organizing information which includes the organization of the information together into relationships that are reminiscent of the class structure found in programming languages. The ontologies are stored within the Semantic Network within DIAS, which preserves this class structure. 5.2.1.2 Geographic Registration As can be seen in Figure 11, two types of ontological information are developed and expanded: 1) lexicographic ontologies, i.e., ontologies of scientific disciplines and remote sensing; and 2) geographic ontologies, as represented by gazetteers. A gazetteer is defined as a reference for information about places and place names used in conjunction with an atlas (hill et Page 54
Architectural Implementation Pilot, Phase 3 Version: 2.0 Global Drought Monitoring and European Drought Observatory-Water SBA Engineering Report Date: 11/Feb/2011 al 1999). The gazetteer assembles a correspondence between place names and spatial information. Each concept (i.e., place) can be uniquely identified by Resource Description framework via a Universal Resource Identifier (URI). Gazetteers can record a triple (place names; geographic footprints (locations); and class of described feature or representation of the real world geographic entity. The place name is a “handle” to support communication. 5.3 EuroGEOSS Deployment of the Foundation Vocabularies Ontologies are created out of scientific vocabularies, controlled vocabularies, where terminology has accepted meaning. So the starting point for the vocabularies in Figure 10 would be general vocabularies, such as: The GEO SBA ontologies were constructed out of: • The General Multilingual Environmental Thesaurus (GEMET): 28 of the 29 languages currently provided by the EIONET portal. • The INSPIRE Feature Concept Dictionary and Glossary: 21 of the 23 EU official languages for INSPIRE Themes, monolingual the other terms. • The ISO 19119 categorisation of spatial data services: 21 of the 23 EU official languages. • The GEOSS Societal Benefit Areas: 5 languages. 5.4 Fine Tuning the Foundation Vocabularies for SBA Application—Specialized Drought Vocabulary At the start of AIP-3, Pozzi parsed the GEMET water thesaurus, in order to identify the extent of drought terminology and concepts contained within it. An extensive, developed network of drought concepts would be necessary to support the presentation graphs in the user interface on the EDO portal (Figure 9) and also provide concepts linked to the drought data and information. However, parsing and browsing the GEMET thesaurus for water shows it lacks any specialized drought vocabulary. 42 Even the precipitation it lists only includes chemical precipitation. 43 Hence, GEMET, by itself, is not adequate to express meteorological drought, agricultural drought, and hydrologic drought indicators or their associated water budget components (groundwater, streamflow, baseflow, snow cover); the base thesaurus must be supplemented by a water ontology. Pozzi (of the Water Working Group), C. Fugazza of the AIP-3 Semantics Working Group, and M. Santoro and S. Nativi, the EuroGEOSS architects, concurred in developing a water ontology that would include a drought specialization that could be used for both EuroGEOSS (and EDO) and the DIAS ontology registration within the semantic 42 http://www.eionet.europa.eu/gemet/theme_concepts?letter=0&start=390&th=40&langcode=en& ns=4 43 http://www.eionet.europa.eu/gemet/theme_concepts?letter=0&start=270&th=40&langcode=en& ns=4 Page 55
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