In 2023–2024, an exceptionally strong Indian Ocean Basin (IOB) warming event occurred following an extreme positive Indian Ocean Dipole (IOD) and coincided with a strong El Niño. A unique feature of this event was the unprecedented and widespread warming in the eastern tropical Indian Ocean (ETIO) during boreal winter (DJF). Unlike previous IOB events (e.g., 1997–1998, 2015–2016, and 2019–2020), where anomalous air-sea heat exchange played a crucial role, the 2023–2024 ETIO warming was primarily driven by oceanic processes. We find that nonlinear zonal and vertical advections played a leading role in triggering the ETIO warming in December, with meridional advections sustaining and broadening the warming through February. This oceanic response reflects distinct dynamical changes in the Walker circulation associated with the co-occurrence of strong positive IOD and El Niño events. Our results highlight the critical role of anomalous atmospheric circulation in modulating oceanic heat redistribution, ultimately triggering the extreme 2023–2024 IOB warming.
 

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