The Effect of Indian Ocean Temperature on the Pacific Trade Winds and ENSO

Abstract

A notable shift in the El Niño‐Southern Oscillation (ENSO) has been observed in the early 21st century, characterized by an increased prevalence of Central Pacific (CP) events and strengthened Pacific trade winds. This shift may be attributed to the warming tropical Indian Ocean (TIO). To investigate this, we conduct perturbation experiments using the Insitut Pierre Simon Laplace climate model and nudge TIO surface temperatures to induce warming or cooling effects. Our findings reveal that TIO warming (or cooling) leads to amplified (weakened) mean trade winds and surface warming (cooling) in the Pacific region. Surprisingly, ENSO variability increases in both TIO cooling and warming scenarios. This result is linked to stronger positive feedbacks and a less stable Bjerknes index for either TIO forcing. Additionally, we find that TIO warming leads to more frequent CP events, meridional widening of wind anomalies, and broadening of the ENSO power spectrum toward lower frequencies.

Warming Tropical Indian Ocean Wets the Tibetan Plateau

“…Hence, both the remote oceans and the local thermal condition are crucial to the plateau wetting trend. Recent studies suggest that the warming Indian Ocean contributes to the Arctic warming (J. Xu et al., 2022) and the ENSO complexity (Ferster et al., 2023). Together with our results, it is indicated that the warming tropical Indian Ocean plays a significant role in shaping the changing climate under global warming and further research efforts are needed to improve our understanding of this role.…”