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

阿古拉斯海流作为“大洋传送带”浅层暖水回流路线的组成部分，作为世界海洋最大的西边界流，在向大西洋输送热量和盐方面发挥着重要作用。印度洋海水“渗漏”到南大西洋，导致了温跃层盐碱化的增加。这种预处理效应为北大西洋深水（NADW）的形成提供了正反馈，从而可能对经向翻转环流的驱动起关键作用。本研究调查了过去3万年“阿古拉斯渗漏”（AL）的变化，试图更好地约束通过渗漏的海水交换在过去的气候变化中作为大西洋主要循环变化的积极参与者的作用。浮游有孔虫的钕同位素组成将用于重建阿古拉斯泄漏强度和位置的变化。研究围绕4个假设展开：1)暖期AL增大（反之亦然），2)消冰期AL增大导致NADW输出增加，3)末次冰期气候过渡期间AL减小导致NADW输出减少，4)全新世和LGM时期Agulhas反射的位置相同。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.