How much does urbanization contribute to extreme heat events in Shanghai: Observations and trend analysis

In 2013 Shanghai has experienced the hottest summer in the last 140 years. Indeed the extreme heat events in Shanghai have occurred more frequently with increasing intensities. The objective of the present paper is to investigate the effect of rapid urbanization since the reform in the 1980s on the temperature change trend of Shanghai. Daily surface air temperature records from 11 weather stations covering both urban and rural areas of Shanghai from1980-2013 were used. The numbers and distributions of hot days and hot nights were studied, which were compared with urban development intensity indices including population density, residential area, energy consumption, and car number etc. selected from census data. On the other hand, remote sensing images, including Landsat TM image and DMSP/OLS nighttime light data were used to derive the spatial pattern of the urban development, which was further compared with the spatial pattern of UHI as derived from the weather station data. Based on the analysis, the paper summarized on the trend of the heat stress induced by urbanization in both temporal and spatial dimensions, and further discussed the possibility for sustainable planning to adapt the urban form to reduce the city's heat vulnerability.