Acta Geographica Sinica ›› 2019, Vol. 74 ›› Issue (9): 1789-1802.doi: 10.11821/dlxb201909007

• Climate Change • Previous Articles     Next Articles

Synergistic interaction between urban heat island and heat waves and its impact factors in Shanghai

AO Xiangyu1,2,4,TAN Jianguo3,4,ZHI Xing5,GUO Jibing6,LU Yiwen1,LIU Dongwei1()   

  1. 1. Shanghai Ecological Forecasting and Remote Sensing Center, Shanghai 200030, China
    2. School of Atmospheric Sciences, Nanjing University, Nanjing 210023, China
    3. Shanghai Climate Centre, Shanghai 200030, China
    4. Shanghai Key Laboratory of Meteorology and Health, Shanghai 200030, China
    5. Department of Science and Technology Development, Shanghai Meteorological Service, Shanghai 200030, China
    6. Fengxian Meteorological Service, Shanghai Meteorological Service, Shanghai 201416, China
  • Received:2018-04-10 Revised:2019-07-18 Online:2019-09-25 Published:2019-09-25
  • Contact: LIU Dongwei
  • Supported by:
    Project of Science and Technology Commission of Shanghai Municipality(17DZ1205300);Project of Science and Technology Commission of Shanghai Municipality(19YF1443900);National Natural Science Foundation of China(41775019);Project of Scientific and Technological Development of the Shanghai Meteorological Service(MS201803)


Under the background of global warming, heat waves are expected to be more frequent and long lasting. Cities endure greater risk under heat wave events because of the pre-existing urban heat island. However, research on the interaction between heat wave and urban heat island is still lacking. Based on hourly data of air temperature, wind speed, relatively humidity, and eddy covariance energy flux data from Shanghai urban (XJH) and rural site (FX) during two summers (June-August) in 2016-2017, the difference of urban heat island (UHI) between heat wave (HW) and non-heat wave (NHW) conditions is analysed. In addition, an advection-diffusion analytical model has been used to unravel the mechanism of the interaction between UHI and HW. Results show that the UHI intensity is obviously enhanced during HWs, and the enhancement is stronger during daytime than that of nighttime, which indicates the synergistic effect between UHI and HW. The relative humidity ratio of urban and suburban areas during HWs significantly decreases compared with NHW conditions, indicating the urban surface becomes even drier than suburban areas during HWs that suppresses evaporation and intensifies UHI intensity. The mean wind speed also has an obvious decrease, leading to weaker advection cooling effect, which has a positive effect on UHI intensity. The increase of net radiation at the urban site is larger than that of the suburban site during HWs so that urban area receives more radiation input. Due to low vegetation cover and more impervious surfaces, the latent heat flux at the urban site has a slight decrease while it has an obvious increase at the suburban site. The increase of the urban sensible heat flux is larger than that of the suburban site. This change of the partition between sensible and latent heat flux also exacerbates the UHI intensity. This study has important implications for cities to cope with intensified thermal risks.

Key words: urban heat island, heat wave, analytical model, radiation flux, sensible heat flux, latent heat flux