Collaborative Research: Determining climate related changes in water mass structure, paleoventilation, and paleocirculation in the Southeast Indian and Southern Oceans

合作研究：确定东南印度洋和南大洋与气候相关的水团结构、古通风和古环流变化

• 批准号: 2231146
• 负责人: Elisabeth Sikes
• 金额: $ 55.66万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-02-01 至 2026-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2231146&HistoricalAwards=false
• 关键词: Collaborative; Research; Determining; climate; related

Today fifty times more CO2 resides in the ocean than the atmosphere. Consequently, exchange of CO2 between the ocean and atmosphere is an important control on atmospheric concentrations. During recent ice ages, atmospheric CO2 was naturally 30% lower than pre-industrial levels. Extensive evidence indicates this reduction was caused by greater storage of CO2 in the ocean. During the last glacial interval, changes in ocean circulation, and the resulting changes in ocean chemistry, are widely believed to have played an important role in storing more CO2 in the ocean. However, there is ongoing debate about the specific state of glacial circulation in the Southern Ocean. Previous studies have largely concentrated in the South Atlantic and Southwestern Pacific. There are clearly changes in the chemistry and circulation of water masses between these two regions, but there remains little information from the critical region of the Southern Indian Ocean. This is where much of the CO2 exchange occurs today. Work for this project will focus on cores collected during a recent cruise to Southeast Indian Ocean waters. These cores provide new material from key locations and ocean depths that are needed to fill this knowledge gap. The samples will be analyzed for isotopes of carbon, oxygen, and neodymium to determine water mass and ventilation histories. Initial analyses recently completed by this research group form the foundation for this work that seeks to determine changes in deep ocean circulation and CO2 sequestration. Collaborations with Australian and British scientists is an integral part of this work as these cores are expected to be an important resource for scientists around the world. This work will also support undergraduate and graduate students, and postdoctoral researchers.The circulation and ventilation of water masses at intermediate depths (~500-1400 m) in the Southern Indian Ocean are central to CO2 partitioning between the atmosphere and ocean. During glaciations, changes in both thermohaline circulation and wind-driven Southern Ocean ventilation are believed to have played important roles in sequestering atmospheric CO2. A detailed understanding of the interaction between the physical mechanisms of thermohaline overturning circulation and wind-driven ventilation requires precise definition of changes in water mass boundaries and properties across the deglaciation. The use of vertical and horizontal transects of sediment core material has been fundamental in identifying past variations in the structure of the ocean. Published transects of paleo-proxies in the glacial South Atlantic differ substantially from the Southwest Pacific, suggesting that processes in the Southeast Indian Ocean had a significant influence on glacial CO2 exchange. Consequently, this proposed work will focus on a selected suite of six cores obtained on the CROCCA-2S cruise in 2018 (Coring to Reconstruct Ocean Circulation and Carbon-dioxide Across 2 Seas). These 6 cores have been selected to create depth and latitudinal transects underlying both subantarctic and subtropical waters in the Southeast Indian Ocean from a region west and south of Australia. Our 18O stratigraphies suggest continuous sedimentation and coherent glacial-interglacial signals between these core sites. Efforts will concentrate on constraining surface frontal locations that shift in response to changes in atmospheric circulation, as well as deep water mass boundaries and properties that vary with changes in meridional overturning circulation patterns. The ultimate scientific objective is to determine the temporal evolution of the horizontal and vertical distribution of proxies that will be used to reconstruct water sources (e.g. 18O and Nd isotopes) and the ventilation history (e.g.13C) in this critical region of the Southern Ocean.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.

今天，海洋中的二氧化碳是大气中的50倍。因此，海洋与大气之间的CO2交换是大气浓度的重要控制因素。在最近的冰河时期，大气中的二氧化碳自然比工业化前的水平低30%。大量证据表明，这种减少是由于海洋中二氧化碳储存量增加所致。在末次冰期期间，海洋环流的变化以及由此产生的海洋化学变化被广泛认为在海洋中储存更多的二氧化碳方面发挥了重要作用。然而，关于南大洋冰川环流的具体状态仍有争论。以前的研究主要集中在南大西洋和西南太平洋。这两个区域之间的水团的化学性质和循环显然发生了变化，但南印度洋关键区域的信息仍然很少。这就是今天大部分二氧化碳交换发生的地方。该项目的工作将侧重于最近在东南印度洋沃茨巡航期间收集的岩心。这些岩心提供了来自关键地点和海洋深度的新材料，需要填补这一知识空白。将对样本进行碳、氧和钕的同位素分析，以确定水体和通风历史。该研究小组最近完成的初步分析构成了这项工作的基础，这项工作旨在确定深海环流和二氧化碳封存的变化。与澳大利亚和英国科学家的合作是这项工作的一个组成部分，因为这些核心预计将成为世界各地科学家的重要资源。这项工作也将支持本科生和研究生，以及博士后研究人员。在南印度洋的中间深度（~500-1400米）的水团的循环和通风是大气和海洋之间的CO2分配的核心。在冰川作用期间，温盐环流和风驱动的南大洋通风的变化被认为在封存大气中的二氧化碳方面发挥了重要作用。详细了解温盐翻转环流和风驱动通风的物理机制之间的相互作用，需要精确定义整个冰消期的水团边界和性质的变化。 利用沉积物岩心材料的垂直和水平剖面是查明海洋结构过去变化的基本手段。已发表的断面的古代理在冰川南大西洋有很大的不同，从西南太平洋，这表明在东南印度洋的过程有重大影响冰川CO2交换。因此，这项拟议的工作将集中在2018年CROCCA-2S巡航中获得的六个岩心的选定套件上（用于重建海洋环流和两洋二氧化碳的取芯）。选择这6个岩心，以创建澳大利亚西部和南部地区东南印度洋亚热带和亚热带沃茨的深度和纬度断面。我们的18 O地层表明这些核心站点之间的连续沉积和连贯的冰川间冰期信号。努力将集中在限制表面锋的位置，转移在大气环流的变化，以及深水质量的边界和属性，随着纬向翻转环流模式的变化而变化。最终的科学目标是确定将用于重建水源的代理的水平和垂直分布的时间演变（如18 O和Nd同位素）和通风历史（例如13 C）该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准。