PS 70-127
Characteristic change and analysis of urban heat island in Beijing city, China, summer, 2003-2011
Urban heat island phenomenon describes the excess warmth of the urban atmosphere and surfaces compared to the non-urbanized rural surroundings. Urbanization process occupied amounts of open spaces, especially agricultural land and green space, which changes the natural land surface features into impervious lands such as buildings and paved lands. In addition, the population increases due to urbanization resulted in the increases of energy consumption. These factors impacted the urban thermal environment. Since Beijing experienced rapid urbanization, and the city expanded in larger-scale and population increased so much, which had effects on the pattern of urban heat island. Based on the landsat TM images of 2003, 2007 and 2011, we are trying to analysis the urban thermal environmental characteristics during these years. Applying the method of retrieval of land surface temperature and using the tools of RS, GIS and Fragstats, The thermal environment and heat island changes in Beijing was analyzed.
Results/Conclusions
The results showed that at the extent of inner city sixth ring road in 2003, although the urban plant cover is the lowest among the three years, the urban heat island is not apparent because of the thermal differences between urban and rural are little. The high temperature areas are mainly distributed outside of southern third ring road and northern fifth ring road. With the urban sprawling and and increases of city’s energy consumption, urban heat island intensity increases. In 2007, the mean temperature is highest at every ring road among three years, the high thermal areas are located evenly inside the study area. In 2011, in spite of the urban plant cover is improved much more than ever, the thermal differences between urban and rural areas is magnified, the maximum and minimum land surface temperature difference reaches to 29.1K, and in the centre of city, the heat island is very apparent. The analysis results of landscape metrics showed that in 2011, the patches number and extent of high-level heat island increased much more than before. Furthermore, within inner fifth ring road, the high level heat island patches connected each other. Because of urban expanded, the shape of heat island patches become more complicated, the dominance of low-level heat island patches decreased, which are important for mitigating urban heat island. Some suggestions for urban planners and natural resources managers were given on mitigating the impact of urban development on heat island.