This study examines a climate model hindcast of the responses of the western Pacific subtropical high (WPSH) to three types of El Niño events: the Eastern Pacific (EP) El Niño and the types I and II of Central Pacific (CP-I and CP-II) El Niño. These El Niño types differ from each other in the central locations and patterns of their sea surface temperature (SST) anomalies. They invoke four different mechanisms to impact the WPSH. Hindcasts produced by the Taiwan Central Weather Bureau (CWB) Climate Forecast System 1-tiered model (TCWB1T1) are analyzed. These hindcasts realistically simulate the impacts on the WPSH during the CP-I El Niño, but overestimate the impacts during the decaying summer of the EP El Niño and during the developing autumn and early winter of the CP-II El Niño. The overestimates are mainly the result of an overly strong Maritime Continent regional circulation mechanism during EP El Niños and an overly strong Indian Ocean capacitor mechanism during CP-II El Niños. Further analyses show that these model biases are related to biases in the simulations of El Niño SST anomalies and the Walker circulation. Both model deficiencies are common to contemporary coupled climate models.

Using observational data and model hindcasts produced by a coupled climate model, we examine the response of the East Asian winter monsoon (EAWM) to three types of El Niño: eastern Pacific (EP) and central Pacific I (CP-I) and II (CP-II) El Niños. The observational analysis shows that all three El Niño types weaken the EAWM with varying degrees of impact. The EP El Niño has the largest weakening effect, while the CP-II El Niño has the second largest, and the CP-I El Niño has the smallest. We find that diverse El Niño types impact the EAWM by altering the responses of two anomalous anticyclones during El Niño mature winter: the western North Pacific anticyclone (WNPAC) and Kuroshio anticyclone (KAC). The WNPAC responses are controlled by the Gill response and Indian Ocean warming processes that both respond to the eastern-to-central tropical Pacific precipitation anomalies. The KAC responses are controlled by a poleward wave propagation responding to the northwestern tropical Pacific precipitation anomalies. We find that the model hindcasts significantly underestimate the weakening effect during the EP and CP-II El Niños. These underestimations are related to a model deficiency in which it produces a too-weak WNPAC response during the EP El Niño and completely misses the KAC response during both types of El Niño. The too-weak WNPAC response is caused by the model deficiency of simulating too-weak eastern-to-central tropical Pacific precipitation anomalies. The lack of KAC response arises from the unrealistic response of the model’s extratropical atmosphere to the northwestern tropical Pacific precipitation anomalies.