Late Quaternary Variability of the Agulhas Thermohaline Valve from Nd Isotopes in Planktonic Foraminifera

作为“大洋输送带”的浅层暖水回流路线的一个组成部分，以及作为世界海洋中最大的西边界流，阿古拉斯海流计划在向大西洋转移热量和盐方面发挥重要作用。印度洋沃茨向南大西洋的这种“渗漏”导致温跃层的盐碱化增加。这种预处理效应为北大西洋深水（NADW）的形成提供了正反馈，从而可能在驱动经向翻转环流中发挥关键作用。这项研究调查了过去30，000年来“阿古拉斯泄漏”（AL）的变化，试图更好地限制海洋水交换通过泄漏在过去气候变化中的作用，作为大西洋主要循环变化的积极参与者。钕同位素组成的浮游有孔虫将被用来重建的Agulhas泄漏强度和位置的变化。研究围绕四个假设：1）在气候变暖期间，AL更大（反之亦然），2）在冰消期AL的增加有助于增加NADW输出，3）在末次冰期气候转型期间，AL的减少有助于减少NADW输出，4）在全新世和末次盛冰期，Agulhas逆反射的位置是相同的。资金支持博士后研究人员和新的古海洋学代理的应用。

As a component of the shallow warm water return route of the "great ocean conveyor", and as the largest western boundary current in the world ocean, the Agulhas Current plans an important role in the transfer of heat and salt into the Atlantic Ocean. This "leakage" of Indian Ocean waters into the South Atlantic contributes to increased salinification of the thermocline. This preconditioning effect provides a positive feedback for North Atlantic Deep Water (NADW) formation, and thereby may play a critical role in driving the Meridional Overturning Circulation. This research investigates changes in the "Agulhas Leakage" (AL) over the last 30,000 years, seeking to better constrain the role that the oceanic water exchange via leakage had in past climate changes as an active player in major circulatory changes in the Atlantic. The neodymium isotopic composition of planktonic foraminifera will be used to reconstruct changes in the Agulhas Leakage intensity and position. The research centers around four hypotheses: 1) the AL is greater during warmer climate periods (and vice versa), 2) increases in AL contributed to increases in NADW export during the deglaciation, 3) decreases in AL contributed to decreased NADW export during the climate transition of the last glacial period, and 4) the position of the Agulhas retroflection was the same during the Holocene and LGM. Funding supports a postdoctoral researcher and application of a new paleoceanographic proxy.