Oman coral δ ¹⁸O seawater record suggests that Western Indian Ocean upwelling uncouples from the Indian Ocean Dipole during the global-warming hiatus

Abstract

The Indian Ocean Dipole (IOD) is an interannual mode of climate variability in the Indian Ocean that has intensified with 20 ^th century global-warming. However, instrumental data shows a global-warming hiatus between the late-1990s and 2015. It is presently not clear how the global-warming hiatus affects modes of climate variability such as the IOD, and their basin-wide ocean-atmosphere teleconnections. Here, we present a 26-year long, biweekly record of Sr/Ca and δ ¹⁸O from a Porites coral drilled in the Gulf of Oman. Sea surface temperature (SST _anom) is calculated from Sr/Ca ratios, and seawater δ ¹⁸O (δ ¹⁸O _sw-anom) is estimated by subtracting the temperature component from coral δ ¹⁸O. Our δ ¹⁸O _sw-anom record reveals a significant regime shift in 1999, towards lower mean δ ¹⁸O _sw values, reflecting intensified upwelling in the western Indian Ocean. Prior to the 1999 regime shift, our SST _anom and δ ¹⁸O _sw-anom show a clear IOD signature, with higher values in the summer of positive-IOD years due to weakened upwelling. The IOD signature in SST _anom and δ ¹⁸O _sw-anom disappears with the overall intensification of upwelling after the 1999 regime shift. The inferred increase in upwelling is likely driven by an intensified Walker circulation during the global-warming hiatus. Upwelling in the Western Indian Ocean uncouples from the IOD.

Contributors

Tsuyoshi Watanabe:

ORCID: http://orcid.org/0000-0002-9372-8994

[e-mail]

Journal

Journal ID (nlm-ta): Sci Rep

Journal ID (iso-abbrev): Sci Rep

Title: Scientific Reports

Publisher: Nature Publishing Group UK (London )

ISSN (Electronic): 2045-2322

Publication date (Electronic): 13 February 2019

Publication date PMC-release: 13 February 2019

Publication date Collection: 2019

Volume: 9

Affiliations

[1 ]ISNI 0000 0001 2173 7691, GRID grid.39158.36, Department of Natural History Sciences, , Faculty of Science, Hokkaido University, ; Sapporo, 060-0810 Japan

[2 ]KIKAI Institute for Coral Reef Sciences, Kikai town, 891-6151 Japan

[3 ]ISNI 0000 0001 2242 4849, GRID grid.177174.3, Department of Earth and Planetary Sciences, Faculty of Science, , Kyusyu University, ; Fukuoka, 819-0395 Japan

[4 ]ISNI 0000 0001 2153 9986, GRID grid.9764.c, Institut für Geowissenschaften, , Christian-Albrechts Universität zu Kiel, ; 24118 Kiel, Germany

[5 ]ISNI 0000 0001 0726 9430, GRID grid.412846.d, Department of Marine Science and Fisheries, College of Agricultural and Marine Sciences, , Sultan Qaboos University, ; Box 34 Al-Khod 123, Sultanate of Oman

Article

Publisher ID: 38429

DOI: 10.1038/s41598-018-38429-y

PMC ID: 6374511

PubMed ID: 30760830

SO-VID: 91b8e513-23d7-4ea4-b6de-9f5a947298df

Copyright statement: © The Author(s) 2019

License:

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Funding

Funded by: FundRef https://doi.org/10.13039/501100001691, MEXT | Japan Society for the Promotion of Science (JSPS);

Award ID: JP25257207

Award ID: 17H04708

Award Recipient : Takaaki K. Watanabe Atsuko Yamazaki

Categories

Subject: Article

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issue-copyright-statement © The Author(s) 2019