Submesoscale instabilities in the ocean bottom boundary layer: A new pathway for energy dissipation

海底边界层的亚尺度不稳定性:能量耗散的新途径

基本信息

  • 批准号:
    1948953
  • 负责人:
  • 金额:
    $ 38.27万
  • 依托单位:
  • 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:
    2020-06-15 至 2023-05-31
  • 项目状态:
    已结题

项目摘要

One of the long standing questions in physical oceanography is how the energy input to the ocean circulation is eventually dissipated, a problem with far-reaching implications for both our basic understanding of ocean circulation and for developing accurate ocean models. Recently it has been suggested that instabilities in the bottom layer and topographic wakes provide an important source of turbulent mixing, however the dynamics and energetics of these instabilities remain largely unexplored. At relatively small scales, where the rotation of the Earth is no longer the dominant factor, called submesoscales, instabilities in the ocean bottom layer modify the extraction, and dissipation of energy from the flow, and hence may alter classic conceptions of bottom turbulence. This research will use theory and idealized high-resolution numerical models to determine how submesoscale instabilities near the bottom, over and downstream of topography, modify turbulent mixing. These instabilities are believed to be common feature near the bottom, but are poorly understood in this setting relative to the surface layers. Likewise, these processes are currently absent in most large-scale ocean models, underscoring the need to develop a quantitative understanding of their impact and dependence on controlling parameters. This understanding is central to problems such as how dense water is brought to the surface in the abyssal overturning circulation, and the exchange of nutrients and other biogeochemical tracers between the bottom and interior layers. Results of this work will improve our understanding, and eventual parameterization, of dynamics along topography, and in particular how these boundary layer processes modify the larger-scale ocean circulation and energetics. This project will also enable the training of a postdoctoral researcher, and support the establishment of the initial research group of a junior faculty member.Preliminary results suggest that submesoscale instabilities in the bottom boundary layer (BBL) open a new pathway for dissipating kinetic energy, and further modify the turbulent mixing of buoyancy near topography, believed to be a key aspect of how dense water is brought back to the surface in the abyssal overturning circulation. These results suggest that classic conceptions of how flow-topography interaction generates turbulence are incomplete, and the role of submesoscale instabilities needs to be considered. This project will investigate the energetics of baroclinic, symmetric, and centrifugal instabilities generated by flow along topography. Large-Eddy Simulation (LES) will be used to examine how these instabilities modify the partitioning and flux of energy between eddy and mean kinetic and potential energy terms, and the irreversible dissipation of kinetic energy and mixing of buoyancy. Reynolds-averaged simulations with variable topography will also be used, in conjunction with the LES, to determine how the upstream BBL evolution influences the energetics of topographic wakes. This work will provide a more complete description of the physical processes, and parameter dependencies, which determine how submesoscale instabilities affect the energetics of the ocean circulation.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.
物理海洋学中一个长期存在的问题是输入到海洋环流中的能量最终是如何耗散的,这个问题对我们对海洋环流的基本理解和开发精确的海洋模型都具有深远的影响。最近有人提出,底层和地形尾流的不稳定性提供了湍流混合的重要来源,然而,这些不稳定性的动力学和能量学仍然在很大程度上未被探索。在相对较小的尺度上,地球的旋转不再是主导因素,称为亚中尺度,海洋底层的不稳定性改变了能量从流动中的提取和耗散,因此可能改变海底湍流的经典概念。这项研究将使用理论和理想化的高分辨率数值模式,以确定如何亚中尺度不稳定性附近的底部,地形,修改湍流混合。这些不稳定性被认为是底部附近的共同特征,但在相对于表层的这种设置中,人们对它们的了解很少。同样,这些过程目前在大多数大型海洋模型中也不存在,这突出表明需要对其影响和对控制参数的依赖性进行定量了解。这一认识对于诸如深海翻转环流中稠密的水如何被带到表面,以及底层和内层之间营养物质和其他生物地球化学示踪剂的交换等问题至关重要。这项工作的结果将提高我们的理解,并最终参数化,动态沿着地形,特别是这些边界层过程如何修改大尺度海洋环流和能量。该项目还将培养一名博士后研究人员,并支持建立一个初级教员的初始研究小组。初步结果表明,底边界层(BBL)中的亚中尺度不稳定性为耗散动能开辟了一条新的途径,并进一步改变了地形附近浮力的湍流混合,这被认为是深海翻转环流中稠密水被带回地表的一个关键方面。这些结果表明,如何流地形相互作用产生湍流的经典概念是不完整的,亚中尺度不稳定性的作用需要考虑。本计画将探讨由沿着地形流动所产生的斜压、对称及离心不稳定性的能量学。大涡模拟(LES)将被用来研究这些不稳定性如何修改涡流和平均动能和势能项之间的能量分配和通量,以及动能的不可逆耗散和浮力的混合。还将使用具有可变地形的Cololds平均模拟,结合LES,以确定上游BBL演变如何影响地形尾流的能量学。这项工作将提供一个更完整的描述的物理过程,和参数的依赖关系,这决定了亚中尺度不稳定性如何影响海洋环流的能量学。这个奖项反映了NSF的法定使命,并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

项目成果

期刊论文数量(2)
专著数量(0)
科研奖励数量(0)
会议论文数量(0)
专利数量(0)
Slippery Bottom Boundary Layers: The Loss of Energy From the General Circulation by Bottom Drag
  • DOI:
    10.1029/2021gl094434
  • 发表时间:
    2021-09
  • 期刊:
  • 影响因子:
    5.2
  • 作者:
    X. Ruan;J. Wenegrat;J. Gula
  • 通讯作者:
    X. Ruan;J. Wenegrat;J. Gula
Insights into the Mixing Efficiency of Submesoscale Centrifugal–Symmetric Instabilities
洞察亚介尺度离心对称不稳定性的混合效率
  • DOI:
    10.1175/jpo-d-21-0259.1
  • 发表时间:
    2022
  • 期刊:
  • 影响因子:
    3.5
  • 作者:
    Chor, Tomas;Wenegrat, Jacob O.;Taylor, John
  • 通讯作者:
    Taylor, John
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Jacob Wenegrat其他文献

Spatial Variability of Marine Heatwaves in the Chesapeake Bay
  • DOI:
    10.1007/s12237-025-01546-9
  • 发表时间:
    2025-05-23
  • 期刊:
  • 影响因子:
    2.300
  • 作者:
    Rachel Wegener;Jacob Wenegrat;Veronica P. Lance;Skylar Lama
  • 通讯作者:
    Skylar Lama

Jacob Wenegrat的其他文献

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{{ truncateString('Jacob Wenegrat', 18)}}的其他基金

Collaborative Research: Tracing the physics of submesoscale entrainment and subduction
合作研究:追踪亚尺度夹带和俯冲的物理过程
  • 批准号:
    2148945
  • 财政年份:
    2022
  • 资助金额:
    $ 38.27万
  • 项目类别:
    Standard Grant
Collaborative Research: The Internal Wave Spectrum and Boundary Mixing in the Sub-Tropical South Atlantic
合作研究:亚热带南大西洋的内波谱和边界混合
  • 批准号:
    2232441
  • 财政年份:
    2022
  • 资助金额:
    $ 38.27万
  • 项目类别:
    Continuing Grant

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