Modulation of the northward penetration of Antarctica intermediate waters into the eastern equatorial Indian Ocean under glacial and interglacial conditions

Article Article scientifique Article Modulation of the northward penetration of Antarctica intermediate waters into the eastern equatorial Indian Ocean under glacial and interglacial conditions eng 2024-03-20 2024-03-20 author Le Houedec Sandrine 0000-0002-4938-5613 944979 author Tremblin Maxime Florian Stephen 919346 author Champion Amaury 870353 author Samankassou Elias 0000-0003-0385-7686 636960 Services communs du département des sciences de la terre (DETCO) 6673 10.1038/s41598-024-57411-5 2045-2322 https://www.nature.com/articles/s41598-024-57411-5 The Indo-Pacific warm pool is the warmest and most dynamic ocean–atmosphere-climate system on Earth and was subject to significant climate changes during the Pleistocene glacial-interglacial transitions. This has been shown to significantly affected the strength of surface waters that redistribute heat from the tropics to the southern part of the Indian Ocean. Here we investigate the response of the oceanic circulation at intermediate depth (1200 m) of the eastern equatorial Indian Ocean (EEIO) with neodymium (Nd) isotopes in the context of the climatic oscillation of the last 500 ka. The most striking feature of our new dataset is the seesaw Nd record that mimics glacial-interglacial cycles. While the interglacial periods are characterized by a higher contribution of the less radiogenic neodymium (~ − 7ε Nd ) Antarctic Intermediate Water (AAIW), the glacial periods are characterized by more radiogenic water mass of Pacific origin (~ − 5ε Nd ). To explain the increase in the ε Nd signature toward a more radiogenic signature as the Indo-Pacific connection is reduced under the low sea level of the glacial periods, we show that under global cooling, the AAIW advances northward into the tropics, which is a consequence of the general slowdown of the thermohaline circulation. Therefore, oceanic mixing at intermediate depth in the eastern tropical Indian intermediate water is modulated by the production rate of the AAIW in the Southern Ocean. Our study provides new evidence for the role that changes in the deep oceanic conditions play in amplifying externally forced climate changes that ultimately lead to drier/moister atmospheric conditions and weaker/stronger monsoons during glacial/interglacial periods over eastern tropical Indian Ocean. Dewey 550 42 Département des sciences de la Terre 154 false 671 Sedimentology, Biostratigraphy and Micropaleontology Scientific reports 14 1 4319ac45-7a75-4504-83f4-1ee9c50875c7 Article (Published version) Public Article-scientifique-from-crossref.pdf 2135729 application/pdf CC BY-4.0 35ae0921dab46f22786962f9ddf4e841173054442dc69f4cc63e5c1b45fba899 openAccess Faculté des sciences / Section des sciences de la Terre et de l'Environnement / Département des sciences de la Terre

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Modulation of the northward penetration of Antarctica intermediate waters into the eastern equatorial Indian Ocean under glacial and interglacial conditions	Scientific reports			2024	115	79

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Champion, Amaury