Design and Implementation of Air Quality Observation System Based on Sensor Web

Urban environment is inherently heterogeneous and vary in location and time continuously. Therefore, monitoring urban environment requires measuring environmental factors at high temporal and spatial scales. Moreover, using spatial web sensors for monitoring environmental phenomena are just essential. In recent years, along with the development of related technologies in production of sensors, which push them to cheaper, smaller and more efficient ones, sensor networks have grown considerably. The wide variety of sensors in terms of communication protocols, data formats and data have been provided by various organizations, the need of interoperable infrastructure to share their data in a standard manner in observation systems is inevitable. So, creating an open spatial data infrastructure to access real-time and archived sensors observations by various organizations is serious for optimal city management.
In order to overcome interoperability obstacles in sharing data of sensor networks, OGC SWE Working Group have been defined open standard protocols and data models for data and sensing devices. The purpose of SWE is providing users the ability of discovery and query from sensor networks, observations and observation methods on the Internet. This process involves identifying sensors capabilities and their measuring quality and access to sensor parameters. These capabilities provides the process and georeferencing observations, retrieve real time and archived observations automatically for software components. From SWE, SOS, SensorML and O&M were utilized. Proposed architecture was built up of three layers including data layer, service layer and application layer. Data layer includes sensors that collect pollutant concentration from physical world. These data will be transferred to and stored in database. Service layer relates the application layer to data layer will be used to publish spatial and non-spatial data on the Internet. Two Server is considered in this layer: SOS server, to publish collected data by the monitoring network from providers’ side to the users’ side at the application layer and the server of spatial data for publishing spatial data over the web. This layer which is considered as the main driver of designed architecture, applies open standards to communicate among other sectors. Application layer includes a web application that runs in the browser. This program involves components that provide for users access to near real-time and archived data of monitoring sensors network of urban pollution. Moreover, include capability of spatiotemporal query from sensors observations and showing the air quality index on the map component for each station.
Due to the benefits of free and open source softwares (FOSS) including simple development and low cost to use them and also the growing tendency of enterprises in applying this kind of softwares, utilized software components in implementation of the mentioned architecture have been selected from this applications. In fact, the main purpose of this study is to provide an open approach on air quality observation system.
Therefore, in this study, a method was presented for establishing a spatial data infrastructure based on sensor web to monitor air quality. In this method, air quality monitoring takes place utilizing service-oriented architecture, open spatial standards and open source software components. The proposed method, was implemented on the air quality monitoring network in Tehran and the results were presented.