The life cycle of internal waves in the ocean: effects of currents and modulational instabilities

海洋内波的生命周期：洋流和调制不稳定性的影响

• 批准号: RGPIN-2019-04879
• 负责人: Lamb, Kevin
• 金额: $ 3.13万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=714649
• 关键词: life; cycle; internal; waves; ocean

Internal waves are examples of nonlinear-dispersive waves, the study of which has been a fascinating and important area of research in fluid dynamics for over 200 years. They exist in the interior of density-stratified fluids when gravitational restoring forces act on vertically displaced fluid. The source of close to half of the internal wave energy in the oceans is tidal currents pushing fluid up and down sloping bathymetry such as the continental slopes and ocean ridges and in recent decades a lot of effort has been expended in understanding the spatial and temporal distribution of this wave source and on the fate of the waves as they propagate away. Internal waves play a fundamental role in transferring energy from large to small scales and in the vertical mixing of heat and nutrients impacting ocean circulation and productivity. They can transport fluid and particles over large distances. Their currents can re-suspend sediments and impact offshore structures. Fish have been observed to migrate vertically in response to the passing of large internal waves to optimize their feeding strategy. Internal waves can propagate thousands of kilometers from their generation site so wave generation in one location can have an impact at great distances. Internal waves appear in many forms including vertically and horizontally propagating internal wave beams and horizontally propagating internal wave modes. Beams are generated at near-critical bottom slopes and have been hypothesized to play a role in shaping the continental shelf. Horizontally propagating waves include internal tides with wavelengths of O(100) km which can evolve into internal solitary waves. My research objectives are to (i) determine how background currents affect internal wave generation by tide-topography interactions and how internal waves interact with ocean currents and eddies; (ii) investigate cross-shelf transport by internal waves; and (iii) to investigate the evolution of horizontally propagating internal wave packets to determine the conditions under which rogue (unusually large) internal waves may form and how the packets may break down. The research will use a mixture of two- and three-dimensional numerical modelling and theory. It will include idealized process studies and numerical simulations based on observations. Theoretical models will be used to understand the complex wave field simulated by these models and, because of their relative simplicity and speed, are often required to more fully explore a parameter space. Sites studied include the Angolan and Peruvian Shelves which are locations of important fisheries, and the Amazon Shelf. This research will contribute to the management of ocean resources and the improvement of our ability to predict the current and future state of the ocean. Members of my research team will gain valuable expertise in high-performance computing, including data analysis and visualization, and skills in working on complex problems.

内波是非线性散射波的实例，该研究是200多年的流体动力学研究领域引人入胜且重要的领域。当重力恢复力作用于垂直移位的流体时，它们存在于密度分层的流体内部。海洋中近一半的内波能的源是潮流的潮流，将流体推向倾斜的测深，例如大陆斜坡和海脊，以及近几十年来，已经花费了很多精力来理解该波源的空间和时间分布，以及它们在传播时的命运。内波在将能量从大尺度转移到小尺度以及影响海洋循环和生产力的垂直混合中起着基本作用。它们可以在大距离上运输流体和颗粒。它们的电流可以重新悬浮沉积物并影响海上结构。已经观察到鱼类会垂直迁移，以响应大型内波的传递，以优化其进食策略。内波可以从其一代地点传播数千公里，因此在一个位置的波浪生成可以在很大程度上产生影响。 内部波浪以多种形式出现，包括垂直和水平传播的内波束和水平传播的内波模式。横梁是在近临界的底坡上产生的，并已假设在塑造大陆架中发挥作用。水平传播波包括具有O（100）km波长的内部潮汐，这些波长可以演变为内部孤立波。 我的研究目标是（i）确定背景电流如何通过潮汐片段相互作用影响内部波浪产生，以及内部波如何与洋流和涡流相互作用； （ii）研究内波的跨架子运输； （iii）研究水平传播内波包的演变，以确定可能形成流氓（异常大的）内部波的条件以及数据包可能如何分解。该研究将使用二维数值建模和理论的混合物。它将基于观察结果包括理想化的过程研究和数值模拟。理论模型将用于理解这些模型模拟的复杂波场，并且由于其相对的简单性和速度，通常需要更充分地探索参数空间。所研究的地点包括安哥拉货架和秘鲁货架，这些货架是重要的渔业地点以及亚马逊货架。这项研究将有助于海洋资源的管理以及提高我们预测海洋当前和未来状态的能力。 我的研究团队的成员将获得高性能计算的宝贵专业知识，包括数据分析和可视化以及解决复杂问题的技能。