Semantically enhancing SensorML with Controlled Vocabularies in the Marine Domain

During the last decade, data produced by sensors have increased exponentially in the environmental domain. Standardization is necessary in order to integrate data originating from disparate sensor networks. Over the last few years, marine organizations and communities have been working towards the standardization of sensors, by implementing OGC SWE (Sensor Web Enablement) standards, i.e. Sensor Model Language (SensorML) to describe sensor metadata, Observations and Measurements (O&M) to describe sensor data and Sensor Observation Service (SOS) to serve them to the world. In addition, many European and US projects such as AtlantOS, SenseOCEAN, BRIDGES, XDomes, FixO3, PANGEA etc. have been implementing OGC SWE standards to achieve machine to machine communication and interoperability with other sensor networks. SensorML is an XML based language that was purposely defined to offer many degrees of flexibility, to describe sensors with different requirements across different domains. SensorML is lenient enough to allow user generated terms to be encompassed in its syntax. As convenient as it sounds, this flexibility can result in many different variations of sensor descriptions, which reduce interoperability and discoverability via the Web. To resolve this, it is important to bring together potential user communities, identify lists of required terms, define them and then use controlled vocabularies to publish them according to standards. In this paper, we will describe the ongoing work done by the marine community, through the Marine SWE Profiles collaboration, to create a more restrictive, semantically richer subset of SensorML, by identifying, formalizing and publishing on the Web the required terms and their definitions according to W3C standards. Keywords— Controlled vocabularies; XML; soft typing; SensorML standardization; NVS2.0