Strengthened ENSO Amplitude Contributed to Regime Shift in the Hadley Circulation

Abstract

Understanding the variability in the Hadley circulation (HC) changes is crucial for understanding ocean‐atmosphere interactions. In this study, the variability in the boreal winter HC in the last 4 decades is explored using multiple reanalyzes and model simulations. The results show that regime shift occurred in the leading mode of HC variability. The primary mode of the recent HC is dominated by an equatorially symmetrical pattern, which was considered the second mode in previous studies. The regime shift in HC variability is mainly due to the El Niño–Southern Oscillation (ENSO), which explains both the spatiotemporal variation and formation of HC variability. Moreover, the abilities of the models to reproduce HC variability is subject to their ability to simulate ENSO variability, suggesting that the ENSO has become a more important modulator of the HC variability in recent decades, and additional research is warranted to evaluate future climate changes and potential effects on the HC.

Atlantic Warming Enhances the Influence of Atlantic Niño on ENSO

“…Nevertheless, we found that model experimental results for El Niño (1991, 1994, 1997), La Niña (1998) and neutral (1990, 1993 years are similar (figures not shown). What remains unclear is the relative importance of the two tropical oceans and/or the Indian Ocean on the multi-decadal modulations of this inter-basin connection (Fan & Meng, 2023;Feng et al, 2023Feng et al, , 2024Zhang & Han, 2021;Zhang & Li, 2023). This warrants a thorough investigation in future studies.…”