EGU21-13911, updated on 04 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Warming of the Indian Ocean weakens the Atlantic Niño - El Niño Southern Oscillation connection 

Shreya Dhame1, Andréa Taschetto1, Agus Santoso1,2, Giovanni Liguori3, and Katrin Meissner1
Shreya Dhame et al.
  • 1ARC Centre of Excellence for Climate Extremes, Climate Change Research Centre, University of New South Wales, Sydney, Australia
  • 2Centre for Southern Hemisphere Oceans Research (CSHOR), CSIRO Oceans and Atmosphere, Hobart, Australia
  • 3ARC Centre of Excellence for Climate Extremes, School of Earth, Atmosphere and Environment, Monash University, Melbourne, Australia

The tropical Indian Ocean has warmed by 1 degree Celsius since the mid-twentieth century. This warming is likely to continue as the atmospheric carbon dioxide levels keep rising. Here, we discuss how the warming trend could influence the El Niño Southern Oscillation (ENSO) via interaction with the Pacific and the Atlantic Ocean mean state and variability. The warming trend leads to the strengthening of easterlies in the western equatorial Pacific, subsequent downwelling and increase of the mixed later depth in the west, and an increase in the subsurface temperature gradient across the equatorial Pacific. In the eastern equatorial Pacific, the response of upwelling ocean currents to surface wind stress decreases, resulting in a weakening of ENSO amplitude. The Indian Ocean warming influences ENSO via the Atlantic Ocean as well. There, it is associated with the strengthening of equatorial easterly winds, and anomalous warming in the west and upwelling induced cooling in the east, especially in austral winter, during the peak of the Atlantic Niño. Consequently, this results in a decrease of the amplitude of Atlantic Niño events and weakening of the Atlantic Niño-ENSO teleconnection, thereby hindering the transition of El Niño events to La Niña events. Thus, the Indian Ocean warming trend is found to modulate tropical Pacific and Atlantic mean state and variability, with implications for ENSO predictability under a warming climate.

How to cite: Dhame, S., Taschetto, A., Santoso, A., Liguori, G., and Meissner, K.: Warming of the Indian Ocean weakens the Atlantic Niño - El Niño Southern Oscillation connection , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13911,, 2021.


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