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: 2230999
• 负责人: Ellen Martin
• 金额: $ 34.97万
• 依托单位: University of Florida
• 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=2230999&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.

如今，二氧化碳居住在海洋中的五十倍。因此，海洋和大气之间的二氧化碳交换是对大气浓度的重要控制。在最近的ICE时代，大气二氧化碳自然比工业前水平低30％。广泛的证据表明，这种减少是由于在海洋中储存的二氧化碳储存量更多。在最后的冰川间隔中，海洋循环的变化以及海洋化学的变化被广泛认为在将更多的二氧化碳存储在海洋中发挥了重要作用。但是，关于南大洋中冰川循环的特定状态存在持续的辩论。先前的研究主要集中在南大西洋和西南太平洋。这两个地区之间的化学和水质量循环显然有变化，但是印度洋南部关键地区的信息很少。这是今天大部分二氧化碳交换发生的地方。该项目的工作将重点放在最近前往印度洋海水的航行期间收集的核心。这些核心提供了从关键位置和海洋深度填补这一知识空白所需的新材料。将分析样品的碳，氧气和霓虹灯的同位素，以确定水质量和通风历史。该研究小组最近完成的初步分析构成了这项工作的基础，该工作旨在确定深海循环和二氧化碳隔离的变化。与澳大利亚和英国科学家的合作是这项工作不可或缺的一部分，因为这些核心有望成为世界各地科学家的重要资源。这项工作还将支持本科生和研究生，以及博士后研究人员。印度洋南部的中级深度（〜500-1400 m）的水量的循环和通风对于大气和海洋之间的二氧化碳分配至关重要。在冰川期间，据信，热盐循环和风驱动的南部海洋通风的变化在隔离大气二氧化碳中起着重要作用。对热盐倾覆的循环和风驱动通风之间物理机制之间的相互作用的详细理解需要精确地定义整个脱水层的水质量边界和特性的变化。 沉积物核心材料的垂直和水平样品的使用对于识别海洋结构的过去变化至关重要。在冰川南大西洋冰川上已发表的横断面与西南太平洋有很大不同，这表明印度洋东南部的过程对冰川CO2的交换产生了重大影响。因此，这项拟议的工作将集中在2018年Crocca-2s Cruise上获得的六个核心的选定套件（加油以重建海洋循环和2海上的碳二氧化物）。已经选择了这6个岩心来创建深度和纬度横断面，从而在印度洋东南部从澳大利亚西部和南部的印度洋东南亚下进行下北极和亚热带水。我们的18o地层表明，这些核心部位之间的连续沉积和相干冰川冰路信号。努力将集中于约束表面额叶位置，这些位置会随着大气循环的变化而转移，以及随着子午倾覆循环模式的变化而变化的深水质量边界和特性。最终的科学目标是确定代理的水平和垂直分布的时间演变，该水平和垂直分布将用于重建水源（例如18O和ND同位素）和通风历史（例如，例如，在这一关键的南方海洋中，这一奖项都在NSF的法定宣称和宽广的范围内，这是NSF的法规及其在宽广的范围内的支持。 标准。