The Concurrent Record-breaking Rainfall over Northwest India and North China in September 2021

Extremely heavy rainfall occurred over both Northwest India and North China in September 2021. The precipitation anomalies were 4.1 and 6.2 times interannual standard deviation over the two regions, respectively, and broke the record since the observational data were available, i.e., 1901 for India and 1951 for China. In this month, the Asian upper-tropospheric westerly jet was greatly displaced poleward over West Asia, and correspondingly, an anomalous cyclone appeared over India. The anomalous cyclone transported abundant water vapor into Northwest India, leading to the heavy rainfall there. In addition, the Silk Road pattern, a teleconnection pattern of upper-level meridional wind over the Eurasian continent and fueled by the heavy rainfall in Northwest India, contributed to the heavy rainfall in North China. Our study emphasizes the roles of atmospheric teleconnection patterns in concurrent rainfall extremes in the two regions far away from each other, and the occurrence of rainfall extremes during the post- or pre-monsoon period in the northern margins of monsoon regions.