North Atlantic Meridional Circulation during the Last Glacial Maximum:Density Structure and Pre-formed Nitrate: Phase I

末次盛冰期的北大西洋经向环流:密度结构和预形成的硝酸盐:第一阶段

• 批准号: 1433150
• 负责人: Arthur Spivack
• 金额: $ 29.97万
• 依托单位: University of Rhode Island
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-15 至 2018-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1433150&HistoricalAwards=false
• 关键词: North; Atlantic; Meridional; Circulation; during

The large-scale conveyor-belt-like circulation of the Atlantic Ocean (the Atlantic Meridional Overturning Circulation, or AMOC) significantly affects climate via its heat flux and its impact on atmospheric carbon dioxide levels. A number of lines of evidence suggest that the structure of the circulation was different during the last ice age, however these reconstructions are indirect. Sedimentary pore waters in the deep sea preserve ancient seawater, and offer the possibility of more directly documenting how AMOC of the last glacial maximum differed from that of the present.This project, led by a team of researchers from the University of Rhode Island, will address these fundamental questions about the links between ocean circulation and climate change. Specifically, funding supports a month-long research expedition to collect long sediment cores along a transect between Puerto Rico and New England. Coring sites would range in depth from 1 to more than 5 km. Coring targets will be chosen with a combination of multibeam swath bathymetry, seafloor backscatter, and CHIRP sub-bottom seismic data. The team would analyze the composition (chloride, dissolved oxygen, and nitrate concentrations) of pore waters in the recovered sediments shipboard to detect the relict signal of deep water chemistry during the last glacial maximum. These measurements will allow the researchers to directly test the influence of glacial circulation on climate (via the pre-formed nitrate content of deep and intermediate water in the LGM North Atlantic). The expedition will include several graduate and undergraduate students, offering a valuable training activity and a strong educational experience.

大西洋的大型传送带式环流（大西洋经向翻转环流，简称AMOC）通过其热通量及其对大气二氧化碳水平的影响显著影响气候。许多证据表明，在最后一个冰河时期，环流的结构是不同的，然而这些重建是间接的。深海中的沉积孔隙水保存了古代海水，并提供了更直接记录末次极大期AMOC与现在不同的可能性。这个项目由罗德岛大学的一组研究人员领导，将解决这些关于海洋环流和气候变化之间联系的基本问题。具体来说，这笔资金将支持一个为期一个月的研究考察，沿着波多黎各和新英格兰之间的样带收集长沉积物岩心。取心地点的深度从1公里到5公里以上不等。取心目标的选择将结合多波束带测深、海底后向散射和CHIRP海底地震数据。研究小组将分析船上回收沉积物中孔隙水的组成（氯化物、溶解氧和硝酸盐浓度），以探测末次盛冰期深水化学的残余信号。这些测量将使研究人员能够直接测试冰川环流对气候的影响（通过在LGM北大西洋深水和中水中预先形成的硝酸盐含量）。这次考察将包括几名研究生和本科生，提供宝贵的训练活动和强大的教育经验。