The Subtropical and Arctic Influences on the Record-Breaking Early Summer Rainfall Over North China in 2022

Abstract

In June–July 2022, North China experienced unprecedented rainfall in the last 75 years, resulting in flood disasters and economic damage. This study examines the related influence factors and physical mechanisms driving North China's anomalous precipitation in June–July 2022. Results show that the simultaneous diabatic heating over northwestern India associated with the local record-breaking precipitation induces an upper-level anticyclonic anomaly over Northeast Asia via exciting the circumglobal teleconnection pattern, which favours intensified upward motion and more precipitation over North China. In addition, the extreme Arctic warming, especially in the Barents-Kara Sea, in June–July 2022 excites a southeastward-propagated Rossby wave train, leading to low-level cyclonic and upper-level anticyclonic anomalies over the Lake Baikal–Ural Mountains regions and Northeast Asia respectively. The anticyclonic (cyclonic) anomalies drive the local divergence anomalies (southerly wind) in the upper (lower) troposphere of North China, favouring more precipitation over there. The numerical simulation based on a linear baroclinic model could reproduce the above-mentioned physical processes.