Collaborative Research: Coring in the Southeast Indian and Southern Oceans to examine climate driven changes in watermass paleoventilation, sources, and structure

合作研究：在东南印度洋和南大洋取芯，以研究气候驱动的水体古通风、来源和结构的变化

• 批准号: 1558605
• 负责人: Ellen Martin
• 金额: $ 32.1万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-02-01 至 2023-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1558605&HistoricalAwards=false
• 关键词: Collaborative; Research; Coring; Southeast; Indian

Fifty times more CO2 resides in the ocean than the atmosphere. Exchange of CO2 with the atmosphere and the storage of CO2 in the ocean is an important control on atmospheric concentrations. During recent ice ages, atmospheric CO2 concentrations were naturally 30% lower than pre industrial levels. Extensive evidence indicates this reduction was caused by greater storage of CO2 in the ocean. Today, wind-driven air-sea exchange in the Southern Ocean is one of the primary mechanisms for CO2 exchange between these two reservoirs. During the last glacial interval, reduced exchange in the Southern Ocean driven by changes in ocean circulation and the resulting changes in ocean chemistry is believed to have played an important role in sequestering more CO2 in the ocean; however, there is ongoing debate about the specific state of glacial oceanic and atmospheric circulation in the Southern Ocean. Current studies are hampered by a lack of suitable sediment cores from key locations; existing cores are 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 is little information available from the critical region of the Southern Indian Ocean where much of the CO2 exchange occurs today. The few cores from this area that do exist have been exhausted over the past 30 years of research. In this study, researchers will collect cores on a cruise to Southeast Indian Ocean waters and conduct the initial shore-based stratigraphic and environmental analyses. Collaborations with Australian scientists will be an integral part of this work and these cores will be an important resource for scientists around the world. The project supports the training of both a graduate student and a postdoctoral researcher.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 work 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 cruise objective is to obtain 30-50 cores 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. The 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. The scientific outcomes will be to produce: 1) the first depth transect of water mass proxies in the Indian Ocean sector of the Southern Ocean over the last glacial cycle, and 2) a latitudinal transect of surface and deep water properties.

二氧化碳居住在海洋中的五十倍。与大气中二氧化碳在海洋中的储存是对大气浓度的重要控制。在最近的ICE时代，大气二氧化碳浓度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。如今，南大洋的风向空气交换是这两个水库之间二氧化碳交换的主要机制之一。 在最后的冰川间隔中，由于海洋循环的变化而驱动的南海洋交换减少，而且海洋化学的变化被认为在隔离海洋中更多的二氧化碳方面发挥了重要作用。但是，关于南大洋中冰川海洋和大气循环的特定状态存在持续的辩论。目前的研究因缺乏关键位置的合适的沉积物核而受到阻碍。现有的核心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，但是从印度洋南部的关键地区，今天大部分二氧化碳交换都发生的信息很少。在过去的30年的研究中，确实存在的几个核心已经耗尽了。在这项研究中，研究人员将在向东南印度洋水域的巡游中收集核心，并进行最初的基于海岸的地层和环境分析。与澳大利亚科学家的合作将是这项工作不可或缺的一部分，这些核心将成为世界各地科学家的重要资源。该项目支持对研究生和博士后研究人员的培训。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 - co2分区的核心。在冰川期间，据信，在热盐循环和风驱动的南洋通风的变化过程中，据信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。在冰川南大西洋冰川上发表的横断面与西南太平洋有很大差异，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，这项工作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深水质量边界和随着海洋循环模式而变化的特性而变化。巡航的目标是获得30-50个岩心，以创建从澳大利亚西部和南部地区的印度洋东南亚海洋下北极和亚热带海水的深度和纬度横断面。科学目标是确定代理水平和垂直分布的时间演变（例如13c，18o，nd同位素），该分布将重建南海这个关键区域的水源和通风历史。 科学的结果将是产生：1）在最后一个冰川周期中，印度洋地区的水质量代理的第一个深度横切，以及2）表面和深水性能的纬度样品。