Roles of ENSO in the Link of the East Asian Summer Monsoon to the Ensuing Winter Monsoon

Abstract

AbstractThe link between the East Asian summer monsoon (EASM) and the ensuing East Asian winter monsoon (EAWM) is investigated. The results found that strong (weak) EASM years are often followed by the strong (weak) EAWM years, demonstrating that the in‐phase EASM to EAWM transition dominate the EASM‐EAWM link. The strong EASM to the strong EAWM transition is established by an anomalous anticyclone over the western North Pacific (WNPAC) in summer and an anomalous cyclone (WNPC) in winter. The weak EASM to the weak EAWM transition is connected by the same way but with the WNPC in summer and the WNPAC in winter. Further studies suggest that ENSO plays a crucial role in the in‐phase EASM to EAWM transition, which forces the transition between the WNPC and WNPAC from summer to winter via inducing Rossby wave responses to the ENSO‐induced convection anomalies. Numerical simulation analysis further confirms the dominant role of ENSO in the in‐phase EASM to EAWM transitions. The asymmetric analysis suggests that the in‐phase EASM to EAWM transition is stronger under El Niño than under La Niña.