text: 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.
  @cite_47: 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).
  @cite_9: Abstract: The Sensor Web is a macro-instrument concept that allows for the spatio-temporal understanding of an environment through coordinated efforts between multiple numbers and types of sensing platforms, including both orbital and terrestrial and both fixed and mobile. Each of these platforms, or pods, communicates within their local neighborhood and thus distributes information to the instrument as a whole. Much as intelligence in the brain is a result of the myriad of connections between dendrites, it is anticipated that the Sensor Web will develop a macro-intelligence as a result of its distributed information with the pods reacting and adapting to their environment in a way that is much more than their individual sum. The sharing of data among individual pods will allow for a global perception and purpose of the instrument as a whole. The Sensor Web is to sensors what the Internet is to computers, with different platforms and operating systems communicating via a set of shared, robust protocols. This paper will outline the potential of the Sensor Web concept and describe the Jet Propulsion Laboratory (JPL) Sensor Webs Project (http: sensorwebs.jpl.nasa.gov ). In particular, various fielded Sensor Webs will be discussed.
  @cite_14: Wireless microsensor networks have been identified as one of the most important technologies for the 21st century. This paper traces the history of research in sensor networks over the past three decades, including two important programs of the Defense Advanced Research Projects Agency (DARPA) spanning this period: the Distributed Sensor Networks (DSN) and the Sensor Information Technology (SensIT) programs. Technology trends that impact the development of sensor networks are reviewed, and new applications such as infrastructure security, habitat monitoring, and traffic control are presented. Technical challenges in sensor network development include network discovery, control and routing, collaborative signal and information processing, tasking and querying, and security. The paper concludes by presenting some recent research results in sensor network algorithms, including localized algorithms and directed diffusion, distributed tracking in wireless ad hoc networks, and distributed classification using local agents.
  @cite_20: 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.
summary: A small clarification on the definition for (wireless) sensor networks may be in order. Mainly within Computing Science (CS) research @cite_14 @cite_20 and in earlier Sensor Web related efforts @cite_9 , this definition is narrower than what is used in this paper. In this more restrictive definition, a (wireless) sensor network is based on nodes (also known as motes'') that have sensing, data storage processing, and communication components plus a power source. These nodes are usually autonomous and operate cooperatively---by communicating amongst themselves---to collect and process data, also being programmable, , able to behave differently according to, for instance, the type of application, power supply conditions, environmental conditions, Although we have used this type of wireless nodes in our deployments, we do not require the capability of offering communication amongst network's components. Instead, we adopt the centralized type of processing architecture as classified by @cite_14 , being more in line with the current Sensor Web approach to networks @cite_47 . It is sufficient for us, for instance, that the connection of sensing elements be done at the level of integrated data products.