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El Niño–Southern Oscillation (ENSO) is a significant interannual phenomenon that occurs every 2–7 years in the tropical Pacific and has global climate impacts linked to natural disasters. Understanding and accurately modeling ENSO dynamics are crucial for predicting its climate impacts and for understanding the characteristics of ENSO itself, such as amplitude, periodicity, and spatial pattern. However, in the latest version of the Australian global climate model ACCESS-CM2 (CM2), the simulated ENSO mainly displays quasi-biennial oscillations (around 2–2.5 years) instead of the observed more irregular 2–7-yr cycles. Our analysis shows that the observed moderate coupling between anomalous western Pacific winds and eastern Pacific sea surface temperature (SST) in May–June is absent in this model. Furthermore, introducing this absence of May–June atmospheric Bjerknes (BJ) feedback in a simple conceptual model of ENSO shifts the ENSO cycle from about 4 years to approximately 2 years, consistent with that simulated in CM2. Subsequently, we conducted a series of idealized atmospheric general circulation model experiments to understand this weakening phenomenon in CM2. The findings demonstrate that the weakening of the May–June air–sea interaction is mainly associated with the representation of SST anomalies in CM2 rather than the simulated mean state bias of the model. This also suggests that biases in CM2's representation of the mean state did not directly impact this weakening of BJ feedback. However, they may play a role in developing SST anomaly biases. Significance Statement: El Niño–Southern Oscillation (ENSO) is a critical climate pattern affecting global weather. The ACCESS-CM2 model shows ENSO happening more regularly than observed, missing some important features. Specifically, the model fails to replicate the link between Pacific winds and sea temperatures during May and June. To understand this, we ran experiments focusing on these discrepancies. Our results indicate that the model's issue during May–June is mainly due to anomalous sea temperature structure rather than other climate factors. This highlights the importance of accurately modeling sea temperature changes to predict ENSO and its global impacts. [ABSTRACT FROM AUTHOR]

Southern China spring rainfall (SCSR) is significant for agricultural sowing and soil moisture accumulation before the rainy summer. A better prediction of the rainfall improves our ability to risk response to natural disasters. It is found that the SCSR can be promoted by multi‐year El Niño events through the high‐latitude pathway (HP) and low‐latitude pathway (LP). The long‐lasting El Niño warming heats the tropical troposphere persistently until the decaying spring, which strengthens the Arctic polar vortex and the mid‐latitude blockings. This HP is in favor of more southward transport of Rossby wave energy and cold air, resulting in strong ascending motions over southern China (SC) in spring. The multi‐year El Niño also induces an enhanced western North Pacific anticyclone and a secondary circulation transporting moisture to SC through the LP. The HP is more important in the early spring, while the LP dominates the heavy SCSR in the late spring. Plain Language Summary: Southern China (SC) experiences a period of rainy time in spring, with the rainband located from South China to the Yangtze River. The southern China spring rainfall (SCSR) is influential for agriculture and soil moisture accumulation before the flood season in summer. A better prediction of the SCSR improves our ability to risk response to natural disasters. El Niño‐Southern Oscillation (ENSO) is the dominant climate signal that exerts significant remote impacts, especially in East Asia. However, whether it can help to predict the SCSR is still unclear. In this study, we show that a particular type of ENSO event, the multi‐year El Niño, initiates remarkable impacts on the SCSR. The long‐lasting Pacific warming favors a HP that transports more cold air and wave energy southward to SC during the decaying spring. Moreover, it also strengthens the western North Pacific anticyclone and generates a meridional secondary circulation with low‐level moisture transport toward SC. The low‐latitude and HPs collaborate to generate strong ascending motions and water vapor convergence in SC, being responsible for the large SCSR. Thus, the remote climate impact of multi‐year ENSO events is distinctive from the other ENSO events. Key Points: Multi‐year El Niño enhances southern China (SC) spring rainfall through both the low‐latitude pathway (LP) and the high‐latitude pathway (HP)Long‐lasting tropical warming supports the HP which transports wave energy and cold air to SC and exerts ascending motionsThese ascending motions and moisture transportation by El Niño‐induced western Pacific anticyclone can be further intensified by the LP [ABSTRACT FROM AUTHOR]