Characterizing the Formation, Nature, and Export of Weddell Sea Bottom Water using Noble Gases and Transient Tracers

使用稀有气体和瞬态示踪剂表征威德尔海底水的形成、性质和输出

• 批准号: 0825394
• 负责人: William Jenkins
• 金额: $ 57.01万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0825394&HistoricalAwards=false
• 关键词: Characterizing; Formation; Nature; Export; Weddell

Intellectual Merit:It is commonly accepted that since at least the last glacial maximum, the substantial millennial-timescale changes in global climate have been caused by, or at least associated with abrupt changes in the oceanic Meridional Overturning Circulation (MOC). There is the lingering suspicion that perhaps the ultimate trigger of the climate transients may lie in the southern hemisphere. Dense waters formed by buoyancy modification on Antarctic shelf regions leave the shelves and sink to comprise the major water mass complex known as Antarctic Bottom Water (AABW). AABW, the coldest and densest water to play a role in the MOC, in turn enters all of the major ocean basins and thereby closes the southern end of the MOC loop. The Weddell Sea features prominently in the production of AABW, where interaction between seawater and the floating ice-shelves produces a unique pre-cursor to AABW by a combination of processes, including) strong heat extraction at ice-edge polynyas, sea-ice formation and export, melting of glacial ice at the grounding line, and formation and deposition of sub-marine sea-ice. These processes not only produce oceanographically and climatically significant injections of fresh water into the AABW pre-cursor, but are hypothesized to have significant impact on its dissolved noble gas composition. We propose to use high precision measurements of the latter as a diagnostic tool of the magnitude of these processes.The investigator will participate in a British research cruise ANDREX which is a section connecting the CLIVAR (CLImate VARiability and predictability Program) repeat line I6S with the Antarctic Peninsula in early 2009. The cruise follows the northern rim of the Weddell Sea gyre, and is ideally situated to study the exchange of water masses across the Antarctic Circumpolar Current. A combination of noble gases, transient tracers (tritium and radiocarbon) along with CFCs, stable isotopes, 3He, and traditional hydrographic measurements will be used to place constraints on an oceanographically and climatically important region.Broader Impacts:This project involves the development and use of novel oceanographic tracers and the application of more traditional tracers in new ways to characterize water mass transformation processes that are of fundamental importance in the operation of the global climate system. The new insights into these processes will provide valuable guidance in the design and construction of the next generation of coupled ocean-atmosphere climate models, which will be of strategic importance in facing the broad range of economic, policy, and societal issues created by climate change. The data set produced in this work will be submitted to the appropriate data centers/repositories to be made available to modelers and climate scientists to guide future research efforts and to evaluate or test existing and future climate models.

学术价值：人们普遍认为，至少自末次盛冰期以来，全球气候千禧年尺度的重大变化是由海洋经向翻转环流（MOC）的突然变化引起的，或者至少与之相关。人们一直怀疑气候瞬变的最终触发因素可能在南半球。南极陆架区域浮力改变形成的稠密水域离开陆架和下沉，构成了被称为南极底水（AABW）的主要水体复合体。 AABW 是 MOC 中最冷、密度最大的水，依次进入所有主要洋盆，从而封闭 MOC 环路的南端。威德尔海在 AABW 的产生中具有突出的特点，其中海水与漂浮冰架之间的相互作用通过一系列过程产生了 AABW 的独特前体，包括）冰边冰间湖的强热提取、海冰的形成和出口、接地线冰川冰的融化以及海底海冰的形成和沉积。这些过程不仅会向 AABW 前体注入具有海洋学和气候学意义的淡水，而且据推测对其溶解的稀有气体成分产生重大影响。我们建议使用后者的高精度测量作为这些过程幅度的诊断工具。研究人员将参加英国研究巡航 ANDREX，这是连接 CLIVAR（气候变化和可预测性计划）重复线 I6S 与2009 年初的南极半岛。巡航沿着威德尔海环流的北缘行驶，地理位置优越，适合研究南极绕极流的水团交换。稀有气体、瞬态示踪剂（氚和放射性碳）以及 CFC、稳定同位素、3He 和传统水文测量的组合将用于对海洋和气候重要区域施加限制。更广泛的影响：该项目涉及开发和使用新型海洋示踪剂的应用以及以新方式应用更传统的示踪剂来表征水团转化过程，这对于全球气候系统的运行至关重要。对这些过程的新见解将为下一代海洋-大气耦合气候模型的设计和构建提供宝贵的指导，这对于应对气候变化带来的广泛的经济、政策和社会问题具有重要的战略意义。这项工作中产生的数据集将提交给适当的数据中心/存储库，以供建模者和气候科学家使用，以指导未来的研究工作并评估或测试现有和未来的气候模型。