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.

项目成果

Evolution of the Oceanic 13 C Suess Effect in the Southeastern Indian Ocean Between 1994 and 2018

1994年至2018年东南印度洋海洋13℃苏斯效应的演变

• DOI: 10.1029/2020gc009402
• 发表时间: 2021-04
• 期刊: Geosystems
• 作者: Williams, Thomas J.;Wagner, Amy J.;Sikes, Elisabeth L.;Martin, Ellen E.
• 通讯作者: Martin, Ellen E.

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: 2021-05
• 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