Boosting effect of strong western pole of the Indian Ocean Dipole on the decay of El Niño events
Abstract 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...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2024-01-01
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| Series: | npj Climate and Atmospheric Science |
| Online Access: | https://doi.org/10.1038/s41612-023-00554-5 |
| _version_ | 1797363507264487424 |
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| author | Jia Wu Hanjie Fan Shuheng Lin Wenxiu Zhong Shan He Noel Keenlyside Song Yang |
| author_facet | Jia Wu Hanjie Fan Shuheng Lin Wenxiu Zhong Shan He Noel Keenlyside Song Yang |
| author_sort | Jia Wu |
| collection | DOAJ |
| description | Abstract 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. |
| first_indexed | 2024-03-08T16:21:27Z |
| format | Article |
| id | doaj.art-6550153fc8b142d9997965e0e89d54f9 |
| institution | Directory Open Access Journal |
| issn | 2397-3722 |
| language | English |
| last_indexed | 2024-03-08T16:21:27Z |
| publishDate | 2024-01-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | npj Climate and Atmospheric Science |
| spelling | doaj.art-6550153fc8b142d9997965e0e89d54f92024-01-07T12:18:20ZengNature Portfolionpj Climate and Atmospheric Science2397-37222024-01-017111110.1038/s41612-023-00554-5Boosting effect of strong western pole of the Indian Ocean Dipole on the decay of El Niño eventsJia Wu0Hanjie Fan1Shuheng Lin2Wenxiu Zhong3Shan He4Noel Keenlyside5Song Yang6School of Atmospheric Sciences, Sun Yat-sen University; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)School of Atmospheric Sciences, Sun Yat-sen University; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)School of Atmospheric Sciences, Sun Yat-sen University; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)School of Atmospheric Sciences, Sun Yat-sen University; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)School of Marine Sciences, Sun Yat-sen UniversityGeophysical Institute, University of BergenSchool of Atmospheric Sciences, Sun Yat-sen University; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)Abstract 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.https://doi.org/10.1038/s41612-023-00554-5 |
| spellingShingle | Jia Wu Hanjie Fan Shuheng Lin Wenxiu Zhong Shan He Noel Keenlyside Song Yang Boosting effect of strong western pole of the Indian Ocean Dipole on the decay of El Niño events npj Climate and Atmospheric Science |
| title | Boosting effect of strong western pole of the Indian Ocean Dipole on the decay of El Niño events |
| title_full | Boosting effect of strong western pole of the Indian Ocean Dipole on the decay of El Niño events |
| title_fullStr | Boosting effect of strong western pole of the Indian Ocean Dipole on the decay of El Niño events |
| title_full_unstemmed | Boosting effect of strong western pole of the Indian Ocean Dipole on the decay of El Niño events |
| title_short | Boosting effect of strong western pole of the Indian Ocean Dipole on the decay of El Niño events |
| title_sort | boosting effect of strong western pole of the indian ocean dipole on the decay of el nino events |
| url | https://doi.org/10.1038/s41612-023-00554-5 |
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