Analysis of an Urban Heat Sink using Thermal Inertia Model from ASTER Data in Beijing, China

More and more problems were emerged with the development of Beijing´s urbanization. One of them is urban heat island (UHI) effect. Our study area is located in the central urban area of Beijing which mainly the area surrounded by the fifth ring road. During our monitoring of the UHI effect using Advance Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data, an urban heat sink was found. This paper focuses on the analysis of this urban heat sink developed in the winter morning of Beijing by detailedly analyzing the subsurface´s thermal characteristics. Thermal inertia was used in thi.s paper to identify the subsurface´s thermal characteristics. Thermal inertia is a physical parameter representing the ability of a material to conduct and store heat, and in the context of planetary science, it is a measure of the subsurface´s ability to store heat during the day and reradiate it during the night. After getting the surface albedo and the land surface temperatures at day and night respectively, the thermal inertia was calculated using a real thermal inertia model. The result shows that the urban area has a bigger thermal inertia than that of the rural area. Which makes the materials in rural area have a rapidly increase in surface temperature then those in the urban area in winter morning which caused the formation of the urban heat sink.