More humid interglacials in Ecuador during the past 500 kyr linked to latitudinal shifts of the equatorial front and the Intertropical Convergence Zone in the eastern tropical Pacific
More humid interglacials in Ecuador during the past 500 kyr linked to latitudinal shifts of the equatorial front and the Intertropical Convergence Zone in the eastern tropical Pacific
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DOI：
10.1029/2009pa001868
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发表时间：
2010-06
期刊：
影响因子：
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通讯作者：
D. Rincón-Martínez;F. Lamy;S. Contreras;G. Leduc;E. Bard;Cornelia Saukel;T. Blanz;A. Mackensen;R. Tiedemann
中科院分区：
文献类型：
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作者：
D. Rincón-Martínez;F. Lamy;S. Contreras;G. Leduc;E. Bard;Cornelia Saukel;T. Blanz;A. Mackensen;R. Tiedemann
[1]研究赤道东太平洋动力学的过去变化及其对陆地降水的影响，使我们能够深入了解热带辐合带(ITCZ)运动和厄尔尼诺-南方涛动如何调节区域和全球气候。在这项研究中，我们介绍了厄瓜多尔海岸外收集的海洋沉积物中陆地输入的多重代理记录，时间跨度为过去500 KYR。同时，我们估计了厄瓜多尔海岸外沉积物的烷酮古测温法得到的海表面温度(SST)，并与巴拿马盆地以北的基于烷酮的SST数据进行了补充，以研究赤道前缘的SST梯度。在赤道附近，今天的河流径流与海温密切相关，在ITCZ向南迁移的南半球夏季或厄尔尼诺事件期间达到最大值。我们对河流径流的多重代理重建表明，间冰期比冰期经历了更潮湿的条件。在冰期，南北海温梯度系统性地变陡，暗示着平均的背景气候状态，具有强烈的海洋冷舌，类似于现代的拉尼娜条件。这种南北SST梯度的增强还意味着热带会聚带冰川向北移动，至少在寒冷的舌头附近：这种模式尚未在气候模型中再现。
[1] Studying past changes in the eastern equatorial Pacific Ocean dynamics and their impact on precipitation on land gives us insight into how the Intertropical Convergence Zone (ITCZ) movements and the El Nino‐Southern Oscillation modulate regional and global climate. In this study we present a multiproxy record of terrigenous input from marine sediments collected off the Ecuadorian coast spanning the last 500 kyr. In parallel we estimate sea surface temperatures (SST) derived from alkenone paleothermometry for the sediments off the Ecuadorian coast and complement them with alkenone‐based SST data from the Panama Basin to the north in order to investigate SST gradients across the equatorial front. Near the equator, today’s river runoff is tightly linked to SST, reaching its maximum either during the austral summer when the ITCZ migrates southward or during El Nino events. Our multiproxy reconstruction of riverine runoff indicates that interglacial periods experienced more humid conditions than the glacial periods. The north‐south SST gradient is systematically steeper during glacial times, suggesting a mean background climatic state with a vigorous oceanic cold tongue, resembling modern La Nina conditions. This enhanced north‐south SST gradient would also imply a glacial northward shift of the Intertropical Convergence Zone at least in vicinity of the cold tongue: a pattern that has not yet been reproduced in climate models.