Internal Waves in the General Oceanic Circulation

一般海洋环流中的内波

• 批准号: RGPIN-2015-03684
• 负责人: Grisouard, Nicolas
• 金额: $ 1.75万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=679814
• 关键词: Internal; Waves; General; Oceanic; Circulation

Internal waves propagate in the volume of the ocean, and are influenced by density variations, as well as the Earth's rotation. When they break, they mix and move water up from the cold abyss, and heat down from the sun-bathed surface. When forced by wind, internal waves are very active in the upper ocean, participate in direct atmosphere-ocean exchanges, and might extract energy out of the large-scale vortices that contain the majority of the ocean's kinetic energy. These vortices are called geostrophic and are characterized by a balance between pressure gradients and the Coriolis force. ***I propose to study how internal waves influence the oceanic circulation over large spatial scales (100 km to global) and long time scales (months to centuries). My group and I will mostly use analytical and numerical tools and organise this program into three main directions. The first direction is about internal tides, namely waves, that oscillate at tidal frequencies. We will investigate how they create or destroy potential vorticity, which is the quantity that best describes geostrophic vortices. We will also study the opposite situation: how internal tides are refracted by geostrophic vortices, and how this unsteady refraction of the tide could affect measurement made by SWOT, the future USA-French satellite altimeter to which Canada also contributes. The second direction will investigate how geostrophic flows lose energy to internal waves when they flow against the corrugated bottom, and how these internal waves eventually dissipate this energy. Our hypothesis is that internal waves interact with deep hydraulic jumps (which could be described as underwater waterfalls) to enhance deep breaking, dissipation and mixing. We will study this phenomenon in two- and three-dimensional numerical simulations. The third direction of research will be to study the interactions between internal waves and small-scale geostrophic flows, such as small vortices or oceanic fronts near the surface of the ocean. We will study how waves propagating in fronts break and how they extract energy out of fronts. We will also undertake a theoretical study to understand the conservation laws that regulate interactions between internal waves and small-scale geostrophic flows. This work might shed light on processes, observable by SWOT.

内波在海洋体积中传播，并受到密度变化和地球自转的影响。当它们破裂时，它们混合并将水从寒冷的深渊中移动，并从阳光沐浴的表面加热。当受到风的推动时，内波在上层海洋中非常活跃，参与直接的大气-海洋交换，并可能从包含大部分海洋动能的大规模漩涡中提取能量。这些涡旋被称为地转涡旋，其特征是压力梯度和科里奥利力之间的平衡。* 我建议研究内波如何影响大空间尺度（100公里到全球）和长时间尺度（几个月到几个世纪）的海洋环流。我和我的团队将主要使用分析和数值工具，并将该程序分为三个主要方向。第一个方向是关于内潮汐，即波浪，以潮汐频率振荡。我们将研究它们如何产生或破坏位涡，位涡是最能描述地转涡的量。我们还将研究相反的情况：如何内潮汐折射的地转涡旋，以及如何这种不稳定的折射的潮汐可能会影响测量的SWOT，未来的美国-法国卫星高度计，加拿大也有助于。第二个方向将调查如何地转流失去能量的内波时，他们对波纹底部流动，以及如何这些内波最终耗散这种能量。我们的假设是，内波与深层水跃（可以描述为水下瀑布）相互作用，以增强深层破碎，耗散和混合。我们将在二维和三维数值模拟中研究这种现象。第三个研究方向是研究内波和小尺度地转流之间的相互作用，如海洋表面附近的小涡旋或海洋锋面。我们将研究波如何在锋面传播，以及它们如何从锋面中提取能量。我们还将进行理论研究，以了解调节内波和小尺度地转流之间相互作用的守恒定律。这项工作可能会揭示的过程中，可观察到的SWOT。