Deglacial δ18O and hydrologic variability in the tropical Pacific and Indian Oceans
Deglacial δ18O and hydrologic variability in the tropical Pacific and Indian Oceans
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DOI：
10.1016/j.epsl.2013.11.032
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发表时间：
2014-02-01
影响因子：
5.3
通讯作者：
Linsley, Braddock K.
中科院分区：
文献类型：
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作者：
Gibbons, Fern T.;Oppo, Delia W.;Linsley, Braddock K.
来自地质档案的证据表明，热带水文循环发生了巨大变化，这与两次显著的北方半球冰消期冷却事件有关，这两次事件分别是海因里希·斯塔迪亚尔1期（HS 1;类似于距今1900年至1500年;距今1000年）和新仙女木期（类似于距今12900年至11700年）。这些水文变化交替归因于高纬度和低纬度起源。在这里，我们提出了一个新的记录水文变率的基础上，南极有孔虫衍生的三角洲O-18的海水（三角洲O-18（SW））估计从沉积物芯从热带东印度洋，并使用12个额外的三角洲O-18（SW）的记录，构建一个单一的记录热带东赤道太平洋和印度太平洋暖池（IPWP）水文变率的主导模式。我们发现，冰消水文变化平行的变化重建的半球间的温度梯度，这表明在大西洋经向翻转环流和随之而来的热量再分配的变化的强烈响应。最后一次冰消的瞬态模型模拟表明，水文变化，包括可能发生在这些北方半球冷事件，加上海洋平流和混合的热带辐合带（ITCZ）的南移，导致在印度尼西亚地区的IPWP和热带太平洋东部，这是由三角洲O-18（SW）代理记录的盐度增加。根据我们的观测和模拟结果，我们认为，半球间的温度梯度直接控制热带水文循环在这些时间尺度上，这反过来又介导向极地大气热量输送。(C)2013作者Elsevier B. V.出版，保留所有权利。
Evidence from geologic archives suggests that there were large changes in the tropical hydrologic cycle associated with the two prominent northern hemisphere deglacial cooling events, Heinrich Stadial 1 (HS1; similar to 19 to 15 kyr BP; kyr BP = 1000 yr before present) and the Younger Dryas (similar to 12.9 to 11.7 kyr BP). These hydrologic shifts have been alternatively attributed to high and low latitude origin. Here, we present a new record of hydrologic variability based on planktic foraminifera-derived delta O-18 of seawater (delta O-18(sw)) estimates from a sediment core from the tropical Eastern Indian Ocean, and using 12 additional delta O-18(sw) records, construct a single record of the dominant mode of tropical Eastern Equatorial Pacific and Indo-Pacific Warm Pool (IPWP) hydrologic variability. We show that deglacial hydrologic shifts parallel variations in the reconstructed interhemispheric temperature gradient, suggesting a strong response to variations in the Atlantic Meridional Overturning Circulation and the attendant heat redistribution. A transient model simulation of the last deglaciation suggests that hydrologic changes, including a southward shift in the Intertropical Convergence Zone (ITCZ) which likely occurred during these northern hemisphere cold events, coupled with oceanic advection and mixing, resulted in increased salinity in the Indonesian region of the IPWP and the eastern tropical Pacific, which is recorded by the delta O-18(sw) proxy. Based on our observations and modeling results we suggest the interhemispheric temperature gradient directly controls the tropical hydrologic cycle on these time scales, which in turn mediates poleward atmospheric heat transport. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.