Revisiting the relationship between El Nino-Southern Oscillation and the East Asian winter monsoon

Previous studies have indicated that the relationship between El Nino-Southern Oscillation (ENSO) and the East Asian winter monsoon (EAWM) weakened significantly after the late 1970s. In this study, the relationship is further analysed based on the impact of different ENSO types. It is found that the relationship between ENSO and the EAWM is related to the ENSO's types. The relationship with the EAWM is strong for eastern Pacific (EP) ENSO but weak for central Pacific (CP) ENSO. The blend of EP and CP ENSO events in the Nino3 index results in a weakened statistical relationship between ENSO and the EAWM. If the pure CP ENSO events are removed from the Nino3 index, the results show that EP ENSO still exerts influence on the EAWM after the late 1970s via its strong connections with the Philippine Sea anticyclone (PSAC) and East Asian trough (EAT), similar to the period before the late 1970s. In contrast, the connections between CP ENSO and the PSAC and EAT are relatively weak, consequently resulting in a weakened relationship between CP ENSO and the EAWM. The influence of mixed (MIX) ENSO on the EAWM is similar to that of EP ENSO. Thus, the EP and MIX ENSO events have had a stable influence on the East Asian winter climate over the past half century, which is significant for the prediction of the East Asian winter climate.