The Changing Impact Mechanisms of a Diverse El Niño on the Western Pacific Subtropical High

The composite analyses during 1950–2016 show that the impacts of El Niño on the western Pacific subtropical high (WPSH) are different among the Eastern Pacific type, Central Pacific type‐I (CP‐I), and Central Pacific type‐II (CP‐II). The three types of El Niño produce distinct impacts on WPSH due to the varying importance of the Northwestern Pacific coupling, Indian Ocean capacitor, and Maritime Continent mechanisms. The different enhancements and cancellations among these three mechanisms are related to differences in SST anomaly locations and Indian Ocean conditions among the El Niño types. The CP‐II El Niño becomes the most influential type of El Niño, while the CP‐I El Niño becomes the least influential type. The different impacts and mechanisms for the CP‐I and CP‐II types of El Niño imply that these two subtypes of CP El Niño may involve different forcing from the Indian Ocean and extratropical Pacific for their generation. Plain Language Summary It is now well recognized that there exists a conventional Eastern Pacific type and an emerging Central Pacific type of El Niño. Recent studies have suggested that the CP El Niño should be further separated into two subtypes. It is shown here that these three El Niño–Southern Oscillation types produce distinct impacts on the western Pacific subtropical high (WPSH). The conventional views of El Niño's impacts on the WPSH and their underlying mechanisms need to be revised to take into account of the El Niño diversity. This study also offers new insights into the generation dynamics of the two subtypes of the CP El Niño. We find that the two subtypes of CP El Niño differ not only in their sea surface temperature anomalies in the northeastern Pacific but also in the Indian Ocean. Key Points El Niño diversity invokes NW Pacific coupling, Indian Ocean capacitor, and MC mechanism to produce distinct impacts on WPSH The changing importance of these mechanisms is caused by different SST anomaly in Pacific and Indian Oceans during various El Niño types The different impacts indicate that CP‐I and CP‐II El Niños are forced by Indian Ocean and extratropical Pacific, respectively