Improvement of community monitoring network data for urban heat island investigation in Hong Kong

The Community Weather Information Network (Co-WIN) was established by the Hong Kong Observatory (HKO) and Hong Kong Polytechnic University (PolyU) in 2007 for promoting weather and climate education. Under Co-WIN, participating members (mainly primary and secondary schools) operate automatic weather stations (AWS) onsite to collect weather data and transmit them to a central database for assimilation and archiving. These Co-WIN AWS are typically located on the rooftops of schools in densely populated areas surrounded by buildings, representing the living environment of the nearby inhabitants. With more than 100 AWSs geographically covering every district of Hong Kong (50 stations operated for 5 years or longer), Co-WIN offers a large set of weather data which are potentially useful in urban climate research. In this study, a Quality Control (QC) procedure tailored made for community network was developed to eliminate the potential errors associated with the power outage, loss in connection and instrumental malfunctions. In the process, the hourly air temperature data extracted from the Co-WIN database was screened with reference to the historical monthly extreme values and the hourly temperature data from nearby HKO stations. Regression analyses were then performed to assess the effects of different elements of urban development (e.g. building density, street configuration, amount of greening and water bodies) on the local temperature. At last, the data was applied to an urban climate study to investigate the relationship between the urban heat island (UHI) effect and the characteristics of the urban environment in Hong Kong. The results demonstrate the community network data can be a useful resource for supplementing the official HKO data for urban climatological study.