SAVI: Collaborative Research: Overturning in the Subpolar North Atlantic - Labrador Basin and Floats

SAVI：合作研究：北大西洋副极地的翻转 - 拉布拉多盆地和浮体

• 批准号: 2017520
• 负责人: Susan Lozier
• 金额: $ 7.3万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-10-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2017520&HistoricalAwards=false
• 关键词: SAVI; Collaborative; Research; Overturning; Subpolar

This project is one of two components of a US-led international program, Overturning in the Sub-polar North Atlantic (OSNAP), designed to provide a continuous record of the full-water column, trans-basin fluxes of heat, mass and freshwater in the subpolar North Atlantic. The OSNAP observing system consists of two legs: one extending from southern Labrador to the southwestern tip of Greenland across the mouth of the Labrador Sea (OSNAP West), and the second from the southeastern tip of Greenland to Scotland (OSNAP East). The observing system also includes subsurface floats (OSNAP Floats) in order to trace the pathways of overflow waters in the basin and to assess the connectivity of currents crossing the OSNAP line. The location of the OSNAP East and West legs purposefully melds with a number of long-term observational efforts in the North Atlantic: the Canadian repeat hydrography program in the Labrador Sea; the German Labrador Sea western boundary array at 53°N; the global Ocean Observatories Initiative node to be placed in the southwestern Irminger Sea; the repeat hydrographic sections across the Irminger and Iceland basins; and the Ellett line in the Rockall region. Substantial international collaboration has been garnered for OSNAP, including measurement contributions from the UK, Germany, the Netherlands and Canada. Importantly, this proposed observing system, in conjunction with the RAPID/MOCHA array at 26°N and the European Union NACLIM program at Nordic Seas overflows, will provide the first comprehensive three-dimensional measure of the Atlantic Meridional Overturning Circulation (AMOC) and provide a means to evaluate inter-gyre connectivity in the North Atlantic. This collaborative project will implement the OSNAP West section and the OSNAP Float program. The primary observational components are: (i) a mooring array across the eastern margin of the Labrador Sea, where the subpolar boundary current enters the basin. This array will complement an analogous array across the western margin at the exit point of the Labrador Sea, maintained by institutions in Germany and Canada; (ii) a sequential release of acoustically tracked floats in the lower limb of the AMOC at the OSNAP East and OSNAP West boundary arrays. These floats will be seeded in the two densest components of North Atlantic Deep Water (NADW) over the four-year period of the measurement program (2014-2018).Intellectual Merit: For decades oceanographers have understood the AMOC to be highly susceptible to changes in the production of NADW. However, a number of recent observational and modeling studies have called into question this supposition, as more has been learned about the role of wind forcing in AMOC variability. Thus, the overall goal of this project is to establish an observing system that will determine the role that intermediate and deep water mass formation and basin-scale wind forcing play in the overturning and associated poleward heat transport, assessments that currently have only been theorized and modeled, but not observed.Broader Impact: In January of 2007, the US Joint Subcommittee on Ocean Science and Technology identified the study of the AMOC as one of four near-term priorities in the US Ocean Research Priorities Plan. This proposed work directly addresses that priority via a design of an AMOC observing system in the sub-polar North Atlantic. While a primary motivation for studying AMOC variability comes from its potential impact on the climate system, additional motivation for the measure of the heat, mass and freshwater fluxes in the sub-polar North Atlantic arises from their potential impact on marine biogeochemistry and the cryosphere. There is growing evidence that the ocean has played (and is playing) a role in the reduction of Arctic sea ice and in mass loss from the Greenland Ice Sheet - both of which have been attributed to changes in the poleward heat transport by the ocean. Also, the ocean plays an essential role in the carbon cycle by moderating increasing atmospheric concentrations of CO2 through the sequestration of anthropogenic carbon in the deep ocean. Variability in the AMOC is expected to impact this sequestration. Broader impacts also include the training of five graduate students in seagoing operations and in the processing and analysis of observational data. The graduate students will have an opportunity to collaborate with their international counterparts through virtual meetings and in-person visits and will be mentored by multiple advisors. This research award includes support for a Science Across Virtual Institutes (SAVI) that is co-funded by NSF's Office of International and Integrative Activities.

该项目是美国主导的国际计划“北大西洋次极地翻转”(OSNAP) 的两个组成部分之一，旨在提供全水柱、跨流域热量、质量和淡水通量的连续记录。 OSNAP 观测系统由两条腿组成：一条从拉布拉多南部穿过拉布拉多海口延伸到格陵兰西南端（OSNAP 西），第二条从格陵兰岛东南端延伸。格陵兰岛至苏格兰（OSNAP 东线）观测系统还包括地下浮标（OSNAP Floats），以便追踪盆地内溢流的路径并评估穿过 OSNAP 线的水流的连通性。西段有目的地与北大西洋的一些长期观测工作相结合：加拿大在拉布拉多海的重复水文学计划；德国拉布拉多海西边界阵列在全球北纬 53 度；海洋观测站倡议节点将位于伊尔明格海西南部；横跨伊尔明格和冰岛盆地的重复水文剖面；以及罗卡尔地区的埃利特线已经为 OSNAP 获得了实质性的国际合作，包括来自英国和德国的测量贡献。重要的是，这个拟议的观测系统与北纬 26° 的 RAPID/MOCHA 阵列和北欧海洋溢出的欧盟 NACLIM 计划相结合，将提供该合作项目将实施 OSNAP 西段和 OSNAP 浮动计划的主要观测部分。 (i) 横跨拉布拉多海东缘的系泊阵列，副极地边界流从这里进入盆地。该阵列将补充横跨拉布拉多海出口点西缘的类似阵列。拉布拉多海，由德国和加拿大的机构维护；(ii) 在 OSNAP 东边界和 OSNAP 西边界阵列的 AMOC 下肢顺序释放声学跟踪浮标。这些浮标将被植入北部最密集的两个部分。大西洋深水（NADW）在测量计划的四年期间（2014-2018）。智力优点：几十年来，海洋学家已经了解 AMOC 很容易受到环境变化的影响。然而，最近的一些观测和建模研究对这一假设提出了质疑，因为人们对风力强迫在 AMOC 变化中的作用有了更多的了解。因此，该项目的总体目标是建立一个观测系统。该系统将确定中层和深水团的形成以及盆地规模的风力强迫在翻转和相关的极地热传输中所起的作用，目前仅进行了理论化和建模，但尚未进行观察评估。更广泛的影响：2007年1月,美国海洋科学与技术联合小组委员会将 AMOC 的研究确定为美国海洋研究优先计划中的四个近期优先事项之一。这项拟议工作通过在子区域设计 AMOC 观测系统来直接解决该优先事项。虽然研究 AMOC 变化的主要动机来自于其对气候系统的潜在影响，但测量北大西洋副极地的热量、质量和淡水通量的额外动机来自于它们对海洋生物地球化学的潜在影响。越来越多的证据表明，海洋在北极海冰减少和格陵兰冰盖质量损失方面发挥了（并且正在发挥）作用——这两者都归因于向极地热传输的变化。此外，海洋通过在深海封存人为碳来减缓大气中二氧化碳浓度的增加，从而在碳循环中发挥着重要作用。AMOC 的变化预计也会影响这种封存。培训五名毕业生从事海上作业以及观测数据处理和分析的学生将有机会通过虚拟会议和面对面访问与国际同事合作，并将获得多名顾问的指导。 Science Across Virtual Institutes (SAVI) 由 NSF 国际和综合活动办公室共同资助。