Collaborative Research: Enhancing our Understanding of North Atlantic Deep Water Pathways using Nonlinear Dynamics Techniques

合作研究：利用非线性动力学技术增强我们对北大西洋深水路径的理解

基本信息

批准号：
1851075
负责人：
Susan Lozier
金额：
$ 34.52万
依托单位：
Duke University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-07-15 至 2024-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1851075&HistoricalAwards=false
关键词：
Collaborative Research Enhancing our Understanding

项目摘要

For most of the last century, the equatorward spread of cold water masses from high latitudes in the Labrador and Nordic Seas was expected to be largely contained along the Deep Western Boundary Current in the subpolar and subtropical North Atlantic. Since the turn of this century, observational floats launched within these water masses have defied this expectation. Instead, myriad interior pathways have been revealed across the North Atlantic. Contemporaneously, an inventory of anthropogenic carbon dioxide has shown the subpolar North Atlantic to be the most intense (per unit area) sink of all ocean basins, a characteristic attributable to the deep penetration of newly-formed water masses in that basin. While the deep limb of the Atlantic Meridional Overturning Circulation has long been appreciated as a heat and freshwater reservoir, its role as a carbon reservoir is now apparent. Thus, at a time when the conventional understanding of these deep water mass pathways has been upended, there is a stronger reason than ever to understand the spread and fate of these water masses. Over the past decade, simulated float trajectories have augmented the relatively small number of observational floats in the North Atlantic in order to gain a broader understanding of water mass pathways. However, analyses of the observed and modeled trajectories have largely used conventional methods to ascertain a limited number of flow characteristics. This study will capitalize on recent advances in nonlinear dynamics in order to provide a more comprehensive description and understanding of these water masses and flows limited observations. Thus, by using these tools to unravel deep water pathways, this project will aid our understanding of the North Atlantic as a deep carbon reservoir, and thereby have a significant societal impact. Broader impacts with this proposed work also include the training of a postdoctoral researcher to facilitate an independent research career and the training of a physical oceanography student in the use of nonlinear dynamical tools. This project will address a fundamental question in modern physical oceanography through the use of two complementary tools emerging at the interface of nonlinear dynamics and fluid dynamics. Probabilistic tools will be used to cast new light on the transformation and fate of the deep waters through the construction of Lagrangian geographies that constrain connectivity, residence times within water mass provinces, preferred circulation pathways, transit times along these pathways, and transport across province boundaries. Deterministic tools that have recently proven efficient at extracting persistent transport pathways will also be used to delineate preferred transport pathways, and thus will be used to frame deep water routes. This offers a promising fertilization of nonlinear dynamical tools into a traditional physical oceanographic area of study. Specifically, this work will apply dynamical systems tools to: 1) determine the long-term fate and elucidate the preferred pathways of the deep water masses; 2) ascertain the extent to which potential vorticity conservation or other dynamics constrains these pathways; and 3) identify spatial provinces (domains) that define water mass residence and evaluate exchanges among them. The small, but growing number of observational floats, including those recently recovered from the Overturning in the Subpolar North Atlantic Program (OSNAP), as well as Argo data and simulated float trajectories from ocean general circulation models, will be used in this analysis.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.

在上个世纪的大部分时间里，在拉布拉多和北欧海中的高纬度地区的冷水量在很大程度上被沿着亚电物质和亚热带北大西洋的深层西部边界电流所包含。自本世纪初以来，在这些水质量中发射的观察浮子违反了这一期望。取而代之的是，北大西洋上已经揭示了无数的内部道路。同时，人为二氧化碳的清单表明，北大西洋的亚极性是所有海洋盆地的最强烈（人均区域）水槽，这是该盆地新形成的水质量深入渗透的特征。尽管长期以来，大西洋子午倾覆的循环的深处一直被欣赏为热量和淡水储层，但现在显而易见其作为碳储层的作用。因此，在对这些深水质量途径的常规理解颠覆的时候，有比以往任何时候都更有原因理解这些水质量的传播和命运。在过去的十年中，模拟的浮点轨迹增加了北大西洋中相对较少的观测浮子，以便对水质量途径有更广泛的了解。但是，对观察到的轨迹和建模轨迹的分析在很大程度上使用了常规方法来确定有限数量的流动特性。这项研究将利用非线性动力学的最新进展，以便对这些水质量和流动的更全面描述和理解有限的观察结果。因此，通过使用这些工具来解开深水道路，该项目将有助于我们对北大西洋作为深碳储层的理解，从而产生重大的社会影响。这项拟议工作的更广泛影响还包括培训博士后研究人员，以促进独立的研究职业以及在使用非线性动力学工具时对物理海洋学学生的培训。该项目将通过在非线性动力学和流体动力学的界面上使用两个补充工具来解决现代物理海洋学中的一个基本问题。概率工具将通过构建限制连通性的拉格朗日地理，水质量省内，首选的循环途径，沿这些途径的运输时间以及跨越省边界的运输来构建深水的转化和命运的新启示。最近已证明有效提取持续运输途径的确定性工具也将用于描述首选的运输途径，因此将用于构建深水路线。这为传统的物理海洋研究领域提供了有希望的非线性动力学工具的受精。具体而言，这项工作将应用动态系统工具：1）确定长期命运并阐明深水质量的首选途径； 2）确定潜在的涡度保护或其他动力学限制这些途径的程度； 3）确定定义水批次住宅并评估其中的交流的空间省份（域）。本分析将使用少量但越来越多的观测浮子，包括从北大西洋亚大西洋计划（OSNAP）倾覆（OSNAP）中回收的那些，以及ARGO数据和来自海洋一般循环模型中的模拟浮标轨迹。该奖项将反映出NSF的法定任务，并通过评估范围来反映了NSF的法定任务，并经过评估的知识范围。