The characteristics of late summer extreme precipitation in northern China and associated large‐scale circulations

Abstract

AbstractExtreme precipitation occurs frequently in northern China. Understanding the characteristics of extreme precipitation is conducive to improving prediction accuracy rates of extreme precipitation events and disaster prevention. An analysis of 55‐year daily precipitation data, which has been represented by R10mm since 1961, reveals non‐uniform variations in late summer extreme precipitation in northern China. The study aims at establishing an objective classification of major impact large‐scale circulations corresponding to extreme precipitation events. Utilizing the circulation classification, this study divides extreme precipitation events into the westerly mode (WM), westerly subtropical mode (WSM) and typhoon mode (TYM), thereby carrying out individual evaluations of types of extreme precipitation in northern China. The results indicate that the frequency distributions of WM and WSM in northern China both have decadal characteristics. Highly frequent WM from the 1980s to the early 2000s is a response to the enhancement of meridionality in westerly winds, which could strengthen the latitudinal positive–negative–positive circulation distribution of Pacific‐Japan wave train patterns in East Asia; however, the late summer WSM in northern China is different from WM. The enhancement (abatement) of the westerly wind meridionality and relatively southward (northward) position of the Western Pacific subtropical high (WPSH) leads to a stretching southward (northward) front rain belt on the northwest edge of WPSH, thereby favouring WSM in Central China and East China (North China, Northeast China and the eastern parts of Northwest China). The decadal variations in the meridionality in westerly winds and WPSH positions are closely related to sea surface temperature anomalies in the North Atlantic and Pacific Decadal Oscillation (PDO), respectively. The results of this study provide theoretical references for decadal extreme precipitation predictions.