Half-precessional cycle of thermocline temperature in the western equatorial Pacific and its bihemispheric dynamics

Type Article
Date 2020-03
Language English
Author(s) Jian Zhimin1, Wang Yue1, Dang Haowen1, Lea David W.2, Liu Zhengyu3, Jin Haiyan1, Yin Yaqian1
Affiliation(s) 1 : State Key Laboratory of Marine Geology, Tongji University, 200092 Shanghai, China
2 : Department of Earth Science, University of California, Santa Barbara, CA 93106, USA
3 : Department of Geography, Ohio State University, Columbus, OH 43210, USA
Source Proceedings Of The National Academy Of Sciences Of The United States Of America (0027-8424) (Proceedings of the National Academy of Sciences), 2020-03 , Vol. 117 , N. 13 , P. 7044-7051
DOI 10.1073/pnas.1915510117
WOS© Times Cited 6
Keyword(s) thermocline temperature, half-precession, western equatorial Pacific, meridional gradient
Abstract

The El Niño−Southern Oscillation (ENSO), which is tightly coupled to the equatorial thermocline in the Pacific, is the dominant source of interannual climate variability, but its long-term evolution in response to climate change remains highly uncertain. This study uses Mg/Ca in planktonic foraminiferal shells to reconstruct sea surface and thermocline water temperatures (SST and TWT) for the past 142 ky in a western equatorial Pacific (WEP) core MD01-2386. Unlike the dominant 100-ky glacial−interglacial cycle recorded by SST and δ18O, which echoes the pattern seen in other WEP sites, the upper ocean thermal gradient shows a clear half-precessional (9.4 ky or 12.7 ky) cycle as indicated by the reconstructed and simulated temperature (ΔT) and δ18O differences between the surface and thermocline waters. This phenomenon is attributed to the interplay of subtropical-to-tropical thermocline anomalies forced by the antiphased meridional insolation gradients in the two hemispheres at the precessional band. In particular, the TWT shows greater variability than SST, and dominates the ΔT changes which couple with the west−east SST difference in the equatorial Pacific at the half-precessional band, implying a decisive role of the tropical thermocline in orbital-scale climate change.

Full Text
File Pages Size Access
Publisher's official version 8 2 MB Open access
Appendix 47 4 MB Open access
Top of the page

How to cite 

Jian Zhimin, Wang Yue, Dang Haowen, Lea David W., Liu Zhengyu, Jin Haiyan, Yin Yaqian (2020). Half-precessional cycle of thermocline temperature in the western equatorial Pacific and its bihemispheric dynamics. Proceedings Of The National Academy Of Sciences Of The United States Of America, 117(13), 7044-7051. Publisher's official version : https://doi.org/10.1073/pnas.1915510117 , Open Access version : https://archimer.ifremer.fr/doc/00614/72647/