Summer long-lived heatwaves in Northeast Asia promote heavy precipitation in South China

Abstract

Heatwaves interact with various extreme weather events, amplifying their impacts beyond the risks associated with high temperatures alone. However, previous research has often overlooked the extent to which heatwaves influence regions beyond their origin. In this study, we introduce a classification of heatwaves in Northeast Asia, distinguishing between long-lived heatwaves (LHWs) lasting five days or more and short-lived heatwaves (SHWs) lasting less than five days. The study highlights the significant role of LHWs in triggering heavy precipitation in South China. The anticyclonic anomalies associated with LHWs are influenced by a slow-moving wave train, initiating and sustaining cyclonic anomalies over South China, resulting in upward airflow anomalies. Additionally, easterly wind anomalies in the southern region of the anticyclonic anomalies facilitate moisture transport to South China, creating favorable conditions for precipitation. The findings underscore that LHWs could account for a noticeable portion (17.6%) of total summer extreme precipitation days in South China. The study highlights the significant role of LHWs-related circulations in triggering heavy precipitation in South China.