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: 1940962
• 负责人: Elisabeth Sikes
• 金额: $ 11.5万
• 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: 2020
• 资助国家: 美国
• 起止时间: 2020-06-01 至 2023-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1940962&HistoricalAwards=false
• 关键词: Collaborative; Research; Determining; climate; related

The modern oceans hold about fifty times more CO2 than the atmosphere, but scientists think this may have been even greater during glacial periods causing a significant reduction in the amount found in the atmosphere. Reduced atmospheric CO2 concentration during ice ages likely contributed to colder global temperatures. Much of the atmospheric-oceanic CO2 exchange takes place in the Southern Ocean and is associated with processes of oceanic and atmospheric circulation. By studying the water mass structure and chemical characteristics, scientists hope to define key controls over the exchange of CO2, namely where water masses rise and sink from the surface and the pathways they travel in the deeper ocean. This study will establish age models and allow detailed correlations between a unique set of sediment cores previously collected from the Indian Ocean. These cores span a range of depths and locations that will support associated efforts of an international team of researchers to study and track important water masses in the area using a variety of chemical tracers found in the sediments deposited as the Earth transitioned out of the last glacial ice age into the modern climate. This work provides undergraduate student research opportunities and supports an early career post-doctoral scientist.The circulation and ventilation of water masses at intermediate depths (~500-1400 m) in the Southern Indian Ocean are central to atmosphere-ocean CO2 partitioning. During glaciations, changes in both thermohaline circulation and wind-driven Southern Ocean ventilation are believed to have played an important role 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, leading to the idea that processes in the Southeast Indian Ocean had a significant influence on glacial CO2 exchange. Consequently, this proposed work will provide foundational stratigraphy in 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. Provisional multi-sensor core logger and CaCO3 data suggest coherent glacial-interglacial stratigraphies between these core sites. Efforts will concentrate on expanding this initial stratigraphy, principally via planktonic and benthic δ18O analyses. Associated efforts will constrain surface frontal locations that shift in response to changes in atmospheric circulation, as well as deep water mass boundaries and properties that vary with ocean circulation patterns. The ultimate scientific objective is to determine the temporal evolution of the horizontal and vertical distribution of proxies (e.g.13C, 18O, Nd isotopes) that will reconstruct the water source and ventilation history of 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.

现代海洋的二氧化碳的二氧化碳比大气高出约五十倍，但科学家认为，在冰川时期，这可能会大大减少大气中的数量。冰河时代降低的大气二氧化碳浓度可能导致全球温度较低。大气 - 海洋二氧化碳交换发生在南大洋，与海洋和大气循环过程有关。通过研究水质量结构和化学特征，科学家希望定义对二氧化碳交换的关键控制，即水质量从表面上升和下沉的地方以及它们在更深的海洋中传播的途径。这项研究将建立年龄模型，并允许以前从印度洋收集的一组独特的沉积物核心之间的详细关联。这些核心跨越了一系列深度和位置，这些核心将支持国际研究人员的相关努力研究和追踪该地区重要的水质量，并使用沉积物中的各种化学示踪剂在地球从最后一次冰川冰河时代转变为现代气候。这项工作提供了学生的研究机会，并支持早期职业博士后科学家。印度洋南部的中间深度（〜500-1400 m）的水质量的循环和通风对于大气中的co2二氧化碳分区至关重要。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发挥了重要作用。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。与西南太平洋的冰川南大西洋冰川的发表了古差异的样本，导致这样的想法是，印度洋东南部的过程对冰川二氧化碳的交换产生了重大影响。因此，这项拟议的工作将在2018年在Crocca-2s Cruise上获得的六个核心的套件中提供基础层学（在2海上重建海洋循环和二氧化碳）。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。临时多传感器核心记录仪和CACO3数据表明，这些核心位点之间的相干冰川间冰层地层。努力将集中于扩展这一初始层学，主要是通过浮游生物和底栖Δ18O分析。相关的努力将限制表面额叶位置，这些位置会随着大气循环变化的响应，以及随着海洋循环模式而变化的深水质量边界和特性。 The ultimate scientific objective is to determine the temporary evolution of the horizo​​ntal and vertical distribution of proxies (e.g.13C, 18O, Nd isotopes) that will reconstruct the water source and ventilation history of this critical region of the Southern Ocean.This award reflects NSF's statutory mission and has been deemed precious of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

项目成果

Neodymium isotope evidence for coupled Southern Ocean circulation and Antarctic climate throughout the last 118,000 years

过去 118,000 年南大洋环流和南极气候耦合的钕同位素证据

• DOI: 10.1016/j.quascirev.2021.106915
• 发表时间: 2021
• 期刊: Quaternary Science Reviews
• 影响因子: 4
• 作者: Williams, Thomas John;Martin, Ellen E.;Sikes, Elisabeth;Starr, Aidan;Umling, Natalie E.;Glaubke, Ryan
• 通讯作者: Glaubke, Ryan