Record-breaking summer rainfall in South Korea in 2020: Synoptic characteristics and the role of large-scale circulations

Abstract In the summer of 2020, South Korea experienced record-breaking rainfall due to 15 consecutive heavy events (HREs) from mid-June early September. Among them, 11 HREs occurred in late June mid-August with distinct synoptic characteristics depending on occurrence period. All 29 27 July (P1) were triggered by extratropical cyclones, while those 28 August (P2) mainly along monsoon rainband. We argue that their transition is associated atmospheric teleconnections. During P1, western North Pacific subtropical high (WNPSH) anomalously extended westward, but its northward expansion was hindered meridional wave train suppressed convection over China Sea. This condition prevented a migration rainband allowed more cyclones pass Korean Peninsula, resulting four HREs. P2, Sea enhanced, and circulation response prompted an abrupt WNPSH large pressure gradient northern boundary. With intensified southwesterly moisture transport, activated producing six The opposite phases Atlantic Oscillation, i.e., negative P1 positive further contributed anomalous modulating mid-latitude convection. study demonstrates nature summertime East Asia can be strongly modulated remote forcings.