TY - JOUR T1 - Half-precessional cycle of thermocline temperature in the western equatorial Pacific and its bihemispheric dynamics A1 - Jian,Zhimin A1 - Wang,Yue A1 - Dang,Haowen A1 - Lea,David W. A1 - Liu,Zhengyu A1 - Jin,Haiyan A1 - Yin,Yaqian AD - State Key Laboratory of Marine Geology, Tongji University, 200092 Shanghai, China AD - Department of Earth Science, University of California, Santa Barbara, CA 93106, USA AD - Department of Geography, Ohio State University, Columbus, OH 43210, USA UR - https://archimer.ifremer.fr/doc/00614/72647/ DO - 10.1073/pnas.1915510117 KW - thermocline temperature KW - half-precession KW - western equatorial Pacific KW - meridional gradient N2 - 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. Y1 - 2020/03 PB - Proceedings of the National Academy of Sciences JF - Proceedings Of The National Academy Of Sciences Of The United States Of America SN - 0027-8424 VL - 117 IS - 13 SP - 7044 EP - 7051 ID - 72647 ER -