Abstract
The relationship between westerly wind bursts (WWBs) and the El Niño-Southern Oscillation (ENSO) diversity has drawn widespread attention. However, the effect of WWBs on the oceanic intraseasonal Kelvin waves in the context of ENSO diversity formation remains largely unexplored due to limited observational data and theoretical analysis. In this study, we employ a combination of 20-90-day bandpass filtering, the complex empirical orthogonal function (CEOF) analysis, and mechanism analysis to investigate the response of oceanic Kelvin wave to WWBs on the background of ENSO diversity. 117 downwelling and 96 upwelling Kelvin waves are identified from filtered sea level anomaly (η) in the equatorial Pacific Ocean (150°E-100°W, 2°S-2°N) during the period of 1993–2017. The WWBs have further east active center, stronger intensity, a larger zonal extent and longer duration during eastern-Pacific (EP) El Niño years compared to central-Pacific (CP) El Niño years. Consistently, Kelvin waves have stronger intensity, broader extension, and continuous spatial distribution along the equator in EP El Niño years than in CP El Niño years. Through statistical analysis and mechanism analysis, comparison of the relationship between WWBs and oceanic response in CP and EP El Niño years implies that WWBs may be a precursor on the formation of ENSO diversity from an oceanic perspective, providing both theoretical significance and practical importance for enhancing the predictability of ENSO diversity.