Dynamic change and spatial expansion of urban heat sinks in Beijing, China

The phenomenon of urban heat island (UHI) and urban heat sink (UHS) has become an object of public concern in recent years with the rapid development of urbanization around the world. This paper focused on the spatial expansion and dynamic change of UHIs in Beijing, China from satellite images. The UHS intensity was indicated by mean plus standard deviation method. An index of spatial expansion intensity was introduced and some sketch maps of spatial extension intensity in 32 directions were represented using equal-fan analysis to show the main sprawl directions of severe UHSs in different periods. The dynamic change of UHS effect during different periods with time span in adjacent years 1988, 1996, 2003, 2006 to 2013 was discussed respectively. The results showed that, the severe UHS expansion direction was not the same during different periods, and the occurrence of severe UHS effect was not always proportional to the development of urbanization, and regions with severe UHS effect increased from 15% to 21% over years from 1988 to 2013.