Integration of CFD-based virtual sensors to a ubiquitous sensor network to support micro-scale air quality management

As a city is urbanized, its landscape becomes more complex owing to the construction of high-rise buildings. The small scale wind-field in an urban district may change frequently owing to the complex terrain, the diverse land use, and high-rise buildings. It also leads to dynamic changes in the air pollution in that area. Conventional urban-scale air quality management systems, however, are unable to effectively manage detailed aspects of such changes. In this study, we set up a micro-scale air quality management system (MAMS) testbed over Konkuk University, Seoul, Korea. A wireless sensor network and a CFD modeling data management system were combined to support the MAMS sensor service. The sensor-based monitoring system showed reasonably good performance for temperature, humidity, and carbon dioxide from inter-comparison studies against conventional large format analyzers. However, the real-world application of a sensor network for air quality monitoring has many limitations, such as limited installation points for 3-dimentional monitoring, limited power availability for continuous monitoring, and limited sensitivity to ambient concentrations. We therefore developed the concept of a "virtual sensor" to provide micro-scale personal air pollution information services, using a CFDbased air quality modeling system. Based on the information provided by the virtual sensors, we developed a futuristic air quality service of the MAMS application for the mobile platform. We found that the combination of CFD-based modeling data with a fast large volume data management system and a mobile visualization system will be a successful intermediate solution for a user-based air quality service before an actual ubiquitous sensor-based system is available to produce micro-scale environmental information for entire urban areas.