Urbanization Amplified Compound Hot Extremes Over the Three Major Urban Agglomerations in China

Abstract Understanding how urbanization affects compound hot extremes (CHEs) is important for the sustainable development in urban agglomeration under global warming. In this study, we investigate the changes of CHEs in summer over the Beijing‐Tianjin‐Hebei region (BTH), Yangtze River Delta (YRD) and Pearl River Delta (PRD) in China, and assess the effects of urbanization on these changes. We find that the frequency and intensity of CHEs in summer show significantly increasing trends in these agglomerations in the recent five decades, particularly in megacities such as Beijing, Shanghai, Guangzhou and Tianjin. The urbanization contributions to CHEs in the YRD and PRD were estimated to 36 ∼ 58%, while relatively small in the BTH, ranging 16 ∼ 29%. They were bonded to the unban size, expansion speed and local climate. In addition to global warming and urbanization, the strengthening continental high and enhancing Western Pacific Subtropical High and its westward displacement were favor to the increased CHEs.