The precession phase of hydrological variability in the Western Pacific Warm Pool during the past 400 ka |
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| Authors: | Kazuyo Tachikawa Olivier Cartapanis Laurence Vidal Luc Beaufort Tatiana Barlyaeva Edouard Bard |
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| Institution: | 1. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China;2. Laboratoire des Sciences du Climat et de l''Environnement, UMR 8212 CEA-CNRS-UVSQ (LSCE), Gif-sur-Yvette 91198, France;3. CNOOC (China) Co., Ltd. Shanghai branch, Shanghai 200030, China;1. Louisiana State University, Department of Geology and Geophysics, Baton Rouge, LA, USA;2. Louisiana State University, Coastal Studies Institute, Baton Rouge, LA, USA;3. Louisiana State University, Department of Oceanography and Coastal Sciences, Baton Rouge, LA, USA;4. Memorial University of Newfoundland, Earth Sciences Department, St. John''s, Newfoundland and Labrador, Canada;1. GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstr. 1-3, 24148 Kiel, Germany;2. Goethe University Frankfurt, Institute of Geosciences, Altenhöferallee 1, 60438 Frankfurt am Main, Germany;3. Alfred-Wegner-Institute Helmholtz Centre for Polar and Marine Research, 27570 Bremerhaven, Germany;1. Department of Geology, Institute of Cenozoic Geology and Environment, State Key Laboratory of Continental Dynamics, Northwest University, 710069, China;2. Institute of Geosciences, Christian-Albrechts-University, Ludewig-Meyn-Str. 10, D-24118 Kiel, Germany;3. Technological Institute of Micropaleontology, Unisinos University, Av. Unisinos 950, 93022-750 São Leopoldo, Brazil |
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| Abstract: | The low-latitude hydrological cycle is a key climate parameter on different timescales, as it contributes to various feedback processes. Modelling studies suggest that the interhemispheric insolation contrast is the major factor controlling the cycle, although the influence of glacial conditions and the phase relationships relative to insolation forcing remain undetermined. In this work, we studied precipitation variability over Papua New Guinea (PNG, 3°S) for the past 400 ka using terrigenous fractions transported by the Sepik River to the Western Pacific Warm Pool (WPWP). A multi-decadal to centennial resolution of the elemental content was obtained using X-ray fluorescence scanning of a marine sediment core using an age model based on 14C dates and benthic foraminiferal δ18O. Indicators of the coarse river particulate fraction (bulk and CaCO3-free basis Ti concentrations, the log intensity ratios of Ti/K and Ti/Ca) displayed a dominant 23 ka periodicity without a clear glacial–interglacial trend. Our precipitation records showed a tight relationship with local summer insolation (3°S, January) with time-dependent lag of 0 to 4 ka. They were generally in anti-phase for U–Th dated Chinese speleothem δ18O records. Based on an analogy to modern climate, we propose that precipitation over PNG was primarily determined by interhemispheric insolation contrast, and the contribution of austral fall/winter precipitation added second-order variability that formed the lags. For the last four climate cycles, the WPWP hydrological cycle was closely associated with the eastern Asian monsoon, and the influence of glacial conditions on the low-latitude hydrological cycle was estimated to be limited. |
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