Given extensive and rapid urbanization globally, assessing regional urban thermal effects (UTE) in both canopy and boundary layers under extreme weather/climate conditions is of significant interest. Rapid population and eco- nomic growth in the Yangtze River Delta (YRD) have made it one of the largest city clusters in China. Here, we ex- plore the three-dimensional (3D) UTE in the YRD using multi-source observations from high-resolution automatic weather stations, radiosondes, and eddy covariance sensors during the record-setting heat wave (HW) of July–Au- gust 2013. It is found that the regional canopy layer UTE is up to 0.6–1.2℃, and the nocturnal UTE (0.7–1.6℃) is larger than daytime UTE (0.2–0.5℃) during the HW. The regional canopy layer UTE is enhanced and expanded northwards, with some rural sites contaminated by the urban influences, especially at night. In the boundary layer, the strengthened regional UTE extends vertically to at least 925 hPa (～750 m) during this HW. The strengthened 3D UTE in the YRD is associated with an enlarged Bowen ratio difference between urban and non-urban areas. These findings about the 3D UTE are beneficial for better understanding of the thermal environment of large city clusters under HW and for more appropriate adaption and mitigation strategies.

Yue MA;Ping LIANG;Sue GRIMMOND;Xuchao YANG;Jun LYU;Yihui DING

Key Laboratory of Cities'Mitigation and Adaptation to Climate Change in Shanghai,Shanghai Regional Climate Center,China Meteorological Administration,Shanghai 200030,China;Shanghai Jiading District Meteorological Bureau,Shanghai 201800,China;Department of Meteorology,University of Reading,Reading RG66ET,United Kingdom;Ocean College,Zhejiang University,Zhoushan 316021,China;Jiangsu Meteorological Information Center,Jiangsu Meteorological Bureau,Nanjing 210008,China;National Climate Center,China Meteorological Administration,Beijing 100081,China

气象学报（英文版）

[1]Yue MA;Ping LIANG;Sue GRIMMOND;Xuchao YANG;Jun LYU;Yihui DING-.Three-Dimensional Urban Thermal Effect across a Large City Cluster during an Extreme Heat Wave: Observational Analysis)[J].气象学报（英文版）,2022(03):387-400

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