Collaborative Research: Examining linkages between the Agulhas Leakage and ocean overturning in the last glacial cycle and through the mid-Pleistocene transition

合作研究：研究末次冰河周期和中更新世过渡期间阿加勒斯泄漏与海洋翻转之间的联系

基本信息

批准号：
1831415
负责人：
Sidney Hemming
金额：
$ 56.01万
依托单位：
Columbia University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2024-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1831415&HistoricalAwards=false
关键词：
Collaborative Research Examining linkages between

项目摘要

Studies of Earth's past climate and oceans are important for developing an understanding of the range of possible behaviors in the climate system. This project seeks to reconstruct the history of the "Agulhas Leakage" from the Indian Ocean into the Atlantic Ocean, and to understand how changes in this leakage are related to past climate and the ocean's circulation. The Agulhas Current is a large boundary current (similar to the Gulf Stream) that flows southward along the southeast African margin. When it gets to the southern tip of Africa, most of the current turns back to the east, but some rings spin off into the Atlantic. This leakage brings water that is saltier than Atlantic water into the Atlantic, and this salt is carried by surface currents, including the Gulf Stream, to the far North Atlantic where it contributes to the formation of North Atlantic Deep Water. Thus, the Agulhas Current system is a key part of the ocean's large-scale overturning circulation. Changes in climate factors in the past may have led to changes in this system, and the goal of this project is to investigate such changes by combining evidence for the surface and deep ocean circulation from sediment cores collected on International Ocean Discovery Program (IODP) Expedition 361. The location of Site U1479 is ideal for making proxy records for both the surface and deep ocean, so it will be possible to simultaneously examine the changes and linkages between Agulhas Leakage and NADW production using a broad suite of geochemical tools. The project involves extensive international collaboration with the scientists from the expedition and will include training and mentorship of a diverse research team that includes undergraduates, graduate students, a postdoctoral fellow and an early career faculty member.The project seeks to detail the relative timing of variability in Agulhas Leakage and North Atlantic Deep Water (NADW) through the last glacial cycle (0-150 kyr) and over the mid-Pleistocene transition (MPT, 0.7-1.3 Ma), an important time of reorganization of the climate system that took place in the absence of changes in the underlying orbital forcing. The variability of Agulhas Leakage will be studied using detailed terrigenous clay provenance analyses, while the NADW variations will be studied with Nd-isotopes in fish teeth and foraminifera coatings. The primary site proposed for the combined deep and surface signal is IODP Site U1479, which is currently bathed in NADW and located where the Agulhas rings are shed into the South Atlantic, comprising the Agulhas Leakage. Additionally, clay provenance proxies from Site U1474, which is located near the beginning of the fully-constituted Agulhas Current, will constrain any end-member changes to the terrigenous composition of the Agulhas endmember. Because the data for both sets of proxies will be collected from the same samples, and also from the same samples that are being processed for benthic isotope stratigraphy, the relative timing of changes in the composition of the Agulhas endmember, the amount of Agulhas leakage, and the changes in NADW will be co-registered. IODP Expedition 361 collected sedimentary records from the broader Agulhas Current System that provide an unparalleled opportunity to examine in detail linkages between the Agulhas Leakage and Atlantic Meridional Overturning Circulation (AMOC) as well as linkages between the Agulhas Current System and southern African climates.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

对地球过去气候和海洋的研究对于发展气候系统中可能行为的范围很重要。该项目旨在重建从印度洋进入大西洋的“ Agulhas泄漏”的历史，并了解这种泄漏的变化与过去的气候和海洋循环有关。 Agulhas电流是沿着非洲东南边缘向南流动的大边界电流（类似于海湾流）。当它到达非洲南端时，大部分目前都转回东部，但有些响声旋转到大西洋。这种泄漏使水比大西洋水更咸的水进入大西洋，这种盐是由包括海湾流在内的地面电流携带的，到达北大西洋远的地方，在那里它有助于北大西洋深水的形成。因此，Agulhas电流系统是海洋大规模倾覆循环的关键部分。过去气候因素的变化可能导致了该系统的变化，该项目的目的是通过结合在国际海洋发现计划（IODP）探险计划（IODP）探险计划（IODP）361的表面和深海循环的证据中调查此类变化。站点U1479的位置U1479的位置U1479的位置是对表面和深海的局限性的理想，因此它可以泄漏，因此它可以泄漏，因此，它可能会泄漏，因此它可以同时进行一定的链接，因此，它可能会链接到一定的链接，因此该站点的链接是一定的。广泛的地球化学工具。该项目涉及与探险队的科学家进行广泛的国际合作，并将包括对包括本科生，研究生，博士后研究员和早期职业教师在内的多元化研究团队的培训和指导（MPT，0.7-1.3 MA），在没有基础轨道强迫变化的情况下，发生气候系统的重要时期。将使用详细的陆质粘土出处分析研究Agulhas泄漏的可变性，而NADW变化将使用鱼牙和有孔虫涂料中的ND同位素进行研究。提议的深层和表面信号提出的主要位点是IODP站点U1479，该位点目前沐浴在NADW，位于Agulhas环被散布到南大西洋的地方，包括Agulhas泄漏。此外，位于完全固定的agulhas电流开始附近的站点U1474的粘土出处代理将限制任何末端成员的变化对Agulhas Endmember的陆续组成。因为这两组代理的数据将从相同的样品中收集，也将从相同的样品中收集的底栖同位素地层学的相同样品，Agulhas End-End-End-End成员组成的相对时间，Agulhas泄漏的量以及NADW的变化将被共同进行。 IODP探险361收集了从更广泛的Agulhas当前系统收集的沉积记录，提供了无与伦比的机会，可以详细检查Agulhas泄漏与大西洋子午线倾覆循环（AMOC）（AMOC）（AMOC）之间的联系，以及Agulhas当前系统与南部非洲临床之间的联系。影响审查标准。