A possible way to extract a stationary relationship between ENSO and the East Asian winter monsoon

Previous studies have revealed that the relationship between the El Niño–Southern Oscillation (ENSO) and the East Asian winter monsoon (EAWM) is not statistically significant when the Pacific Decadal Oscillation (PDO) is in its positive phase. This study explores a possible way to obtain a robust ENSO–EAWM relationship from a dynamical point of view. Here, the authors show that the East Asian winter temperature is significantly and continuously correlated with ENSO when the linear impact of the PDO has been linearly removed from ENSO. Such a conclusion is confirmed by different reanalysis datasets. The dynamical process intensifying the ENSO–EAWM is further investigated from the perspective of whether or not the atmospheric teleconnection between the Pacific and East Asia has established. Compared to the situation associated with the original ENSO in the positive phase of the PDO, the Walker circulation associated with the processed ENSO, from which the effect of North Pacific climate systems has been removed, tends to exert a more pronounced influence on the atmospheric circulation over the western North Pacific. Consequently, an anomalous anticyclone emerges in the Kuroshio extension. In this sense, the Pacific–East Asian teleconnection is also well established during the positive phase of the PDO, which favors the impact of ENSO on East Asian winter temperature.