Simulation of thermal effects due to different amounts of urban vegetation within the built-up area of Beijing, China

Abstract

Urban heat islands (UHI) are a common phenomenon in most cities, and one of the most effective ways to mitigate UHI negative effects is with urban vegetation. This paper uses the mono-window algorithm for retrieving land surface temperature (LST) based on remote-sensing data, and simulates thermal effects in five situations, using different amounts of urban vegetation within the built-up area of Beijing. Our analyses indicated that the computed Near Surface Air Temperature (NSAT) of the current situation (25 July 2005) was 295.86 K at 02:47 which is comparable to the real observed mean NSAT (296 K) at that time. When all urban vegetation was removed, the mean LST and NSAT increased by 1.95 K and 0.92 K compared to the current situation. In addition, the mean NDVI (normalized difference vegetation index) increased to 0.22–0.42, while the mean NSAT decreased to 294.98–293.08 K, which is close to a temperature comfortable to humans (295–293 K) in that area. Our work should provide information for the government of Beijing and the public on the importance of urban vegetation in counteracting effects of UHI during urban land use and management projects.

Keywords:

• urban heat island
• urban vegetation
• cooling effect
• land surface temperature
• near surface temperature
• Landsat 5 TM
• NDVI

Acknowledgements

We thank the following foundations for support, the National Nature Science Foundation of China (70,433,001) and the Knowledge Innovation Project of The Chinese Academy of Sciences (KZCX2-YW-422 and KZCX2-YW-324). We would also like to thank the staff of the Research Centre of Eco-Environmental Sciences, CAS and the reviewers who helped improve this paper.