Collective effects of synoptic processes and equatorial waves on the genesis of a strong westerly wind burst event in late 2023

Abstract

A strong westerly wind burst (WWB) event that occurred from November 6 to 16, 2023 has been suggested to have substantially influenced the development of the strong 2023/24 El Niño, yet the mechanisms governing its genesis remain poorly understood. Our analysis indicates that the Madden–Julian Oscillation and equatorial convective Rossby waves jointly initiated the event, with the latter playing the dominant role. During the intensification phase, southerly anomalies associated with mid‑latitude low‑pressure systems in the Southern Hemisphere sharply reinforced the WWB, while an East Asian cold surge and Tropical Cyclone Mal further amplified it during its peak. Given the crucial role of WWBs on ENSO evolution, our findings suggest that accurate El Niño prediction by current climate models will remain difficult unless synoptic‑scale processes closely related to WWBs can be adequately simulated.