Modeling the Monthly Variations of Urban Heat Island in Beijing City with MODIS Surface Products

As a climatic phenomenon, the urban heat island (UHI) obtains intrinsic variation characteristics at different temporal scales. However, investigations on the intra-annual variations of UHI in mega cities are still rare. In this study, high-quality LST time-series datasets of the Beijing municipality are generated from MODIS (Moderate-resolution Imaging Spectroradiometer) surface products, for investigating the monthly variations of UHI in Beijing city. These time-series datasets cover the periods of 2001-2008 (for 10:30 and 22:30 local solar time) and 2003-2008 (for 13:30 and 01:30 local solar time). Results demonstrate that the daytime UHI effect of Beijing city was most significant in the summer (August), while it was weakest in the winter (January and February). Generally speaking, there were urban heat sink phenomena in the city of Beijing in winter or March, but the city appeared as heat islands in conditions with snowfalls. The UHI intensity in the afternoon (13:30 local time) was commonly higher than that in the morning (10:30 local time). For the nighttime UHI of Beijing, it was most significant in the winter (January) and weakest in the summer (July). The UHI intensity in the middle-night was commonly lower than that in the evening. The monthly variations of UHI of Beijing city are related with the climatic background, meteorological conditions, and surface characteristics.