Ecosystems monitoring is essential to properly understand their development and the effects of events, both climatological and anthropological in nature. The amount of data used in these assessments is increasing at very high rates. This is due to increasing availability of sensing systems and the development of new techniques to analyze sensor data. The Enviro-Net Project encompasses several of such sensor system deployments across five countries in the Americas. These deployments use a few different ground-based sensor systems, installed at different heights monitoring the conditions in tropical dry forests over long periods of time. This paper presents our experience in deploying and maintaining these systems, retrieving and pre-processing the data, and describes the Web portal developed to help with data management, visualization and analysis.
These and other initiatives, aiming at integration of ground-based monitoring efforts, are leading to an evolution from single site environmental monitoring into networks for environment observation @cite_8 . This evolution culminates with the current vision for a Sensor Web @cite_9 @cite_39 @cite_47 , encompassing several types of deployments of sensor systems, interconnecting them globally through a Web-based integration strategy using standards developed by the Sensor Web Enablement ( http: www.opengeospatial.org projects groups sensorweb ) Working Group of the Open Geospatial Consortium, Inc. (OGC) ( http: www.opengeospatial.org ).
@cite_9 @cite_47 @cite_39 @cite_8
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This paper provides an overview of sensor webs from the perspective of Earth observation. Definitions of in-situ, proximal, and remote sensing are presented. Sensor webs are also defined and the over-arching concept of integrated Earth sensing is outlined. The paper goes on to describe experiences in the development and deployment of sensor web prototypes in support of vegetation monitoring applications. Recommendations are provided with regard to where the emphasis should be placed for advancing in-situ sensor webs in the context of Earth observation in the future. Finally, the geostrategic importance of integrated Earth sensing, sensor webs and related technologies is discussed. The developments in wireless network technology and miniaturization makes it possible to realistically monitor the natural environment. Within the field of environmental sensor networks, domain knowledge is an essential fourth component. Before designing and installing any system, it is necessary to understand its physical environment and deployment in detail. Sensor networks are designed to transmit data from an array of sensors to a server data repository. They do not necessarily use a simple one way data stream over a communication network rather elements of the system decide what data to pass on, using local area summaries and filtering to minimize power use while maximizing the information content. The Envisense Glacs Web project is developing a monitoring system for a glacial environment. Monitoring the ice caps and glaciers provides valuable information about the global warming and climate change. The Open Geospatial Consortium (OGC) standards activities that focus on sensors and sensor networks comprise an OGC focus area known as Sensor Web Enablement (SWE). Readers interested in greater technical and architecture details can download the OGC SWE Architecture Discussion Paper titled "The OGC Sensor Web Enablement Architecture" (OGC document 06-021r1). The continual advancement in semiconductor technology has enabled vendors to integrate an increasing number of sensors, e.g., accelerometer, gyroscope, digital compass, high resolution cameras and others, in modern mobile phones. Combining with the ever expanding market penetration of mobile phones, the onboard sensors are driving the sensing community towards a new paradigm called participatory sensing in which ordinary citizens voluntarily collect and share information from their local environment using personal mobile devices. The inherent openness of this platform is a double-edged sword. While encouraging user participation on the one hand, it also makes it easy to contribute corrupted data. As such, data trustworthiness becomes a key issue which needs to be addressed to ensure sustainable development of this emerging paradigm. In this paper, we propose a reputation system in which a reputation score is calculated for each device as a reflection of the trustworthiness of its sensor data. We adopt the Gompertz function as a fundamental building block of our system, since it is better suited to deal with the unique characteristics of participatory sensing. We present an application-agnostic implementation of the system, which can work with a wide variety of participatory sensing applications. We evaluate the performance of our reputation system in the context of two real-world participatory sensing applications. Our results show that the proposed reputation system outperforms existing solutions by up to a factor of six.