Abstract. A Wide-Area Sensor Network (WASN) is a collection of heterogeneous sensor networks and data repositories spread over a wide geographic area. The diversity of sensor types and the regional differences over which WASNs operate result in semantic interoperability mismatches among sensor data, and a difficulty in agreeing on methods for sensor data access and exchange. We assume that sensors and their associated data have an explicit spatio-temporal basis (or tagging) in their representation. In this paper, we describe a spatio-temporal looselycoupled federated database model for the WASN data storage problem that of unifying query and data representation given a heterogeneous WASN - and propose a conceptual schema to ease the problem of integration of sensor data representations. This is a continuing and critical challenge as sensor networks become more ubiquitous and data interoperation becomes increasing vital for a variety of applications (such as homeland security, transpor...