Local and Cross‐Basin Driving Mechanisms for Marine Heatwaves in the Kuroshio Extension Region

Abstract

Marine heatwaves (MHWs)—prolonged periods of anomalously warm ocean temperatures—have intensified in recent decades, exerting profound impacts on marine ecosystems and fisheries. Using the OISST V2.0 data set from 1982 to 2023, this study examines the distribution characteristics of MHWs in the Kuroshio Extension Region (KER). The local drivers of KER MHWs are quantified through anomalies of the mixed‐layer heat budget, and the influences of interoceanic teleconnections are further assessed. The results show that the KER is one of the most intense MHW regions in the North Pacific, characterized by strong variability, and its cumulative intensity increases at a rate 2.1‐folds faster than the entire North Pacific. The local formation mechanisms of KER MHW events exhibit pronounced seasonality: atmospheric heat flux makes the largest contribution from spring to autumn and dominates in summer (contributing 54.4%), while ocean advection also plays an important role in spring and autumn; in winter, ocean advection becomes the dominant driver (contributing 67.8%). Under the regulation of large‐scale climate modes, remote North Atlantic sea surface temperature anomalies can also influence KER MHWs through atmospheric teleconnections. Specifically, AMO‐like North Atlantic SSTA can excite eastward‐propagating Rossby wave trains, promoting high‐pressure anomalies over the KER and triggering MHWs through local processes. This study provides new insights into the driving mechanisms of MHWs in the KER and their link to atmospheric circulation.