Boosting effect of strong western pole of the Indian Ocean Dipole on the decay of El Niño events

The Indian Ocean Basin (IOB) mode is believed to favor the decay of El Niño via modulating the zonal wind anomalies in the western equatorial Pacific, while the contribution of the Indian Ocean Dipole (IOD) mode to the following year’s El Niño remains highly controversial. In this study, we use the...

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Bibliographic Details
Published inNPJ climate and atmospheric science Vol. 7; no. 1; pp. 6 - 11
Main Authors Wu, Jia, Fan, Hanjie, Lin, Shuheng, Zhong, Wenxiu, He, Shan, Keenlyside, Noel, Yang, Song
Format Journal Article
LanguageEnglish
Published London Nature Publishing Group UK 03.01.2024
Nature Publishing Group
Nature Portfolio
Subjects
704/106
704/106/35
Anomalies
Atmospheric Protection/Air Quality Control/Air Pollution
Atmospheric Sciences
Climate Change/Climate Change Impacts
Climatology
Convection
Decay
Dipoles
Earth and Environmental Science
Earth Sciences
El Nino
Kelvin waves
Ocean basins
Thermocline
Upwelling
Wind
Indian Ocean
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Summary:The Indian Ocean Basin (IOB) mode is believed to favor the decay of El Niño via modulating the zonal wind anomalies in the western equatorial Pacific, while the contribution of the Indian Ocean Dipole (IOD) mode to the following year’s El Niño remains highly controversial. In this study, we use the evolution of fast and slow decaying El Niño events during 1950–2020 to demonstrate that the positive IOD with a strong western pole prompts the termination of El Niño, whereas a weak western pole has no significant effect. The strong western pole of a positive IOD leads to a strong IOB pattern peaking in the late winter (earlier than normal), enhancing local convection and causing anomalous rising motions over the tropical Indian Ocean and sinking motions over the western tropical Pacific. The surface equatorial easterly wind anomalies on the western flank of the sinking motions stimulate oceanic equatorial upwelling Kelvin waves, which shoal the thermocline in the eastern equatorial Pacific and rapidly terminate the equatorial warming during El Niño. However, a weak western pole of the IOD induces a weak IOB mode that peaks in the late spring, and the above-mentioned cross-basin physical processes do not occur.
ISSN:2397-3722
2397-3722
DOI:10.1038/s41612-023-00554-5