Internal Waves in the General Oceanic Circulation

内波在海洋的体积中传播，受到密度变化和地球自转的影响。当它们破裂时，它们混合并将水从冰冷的深渊中向上移动，然后从沐浴在阳光下的表面向下加热。当受到风的强迫时，内波在上层海洋中非常活跃，参与直接的大气-海洋交换，并可能从包含海洋大部分动能的大范围漩涡中提取能量。这些涡旋被称为地转涡旋，其特征是气压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，并将这个项目组织成三个主要方向。第一个方向是关于内部潮汐，即以潮汐频率振荡的波。我们将研究它们如何产生或破坏位涡，位涡是最好地描述地转涡的量。我们还将研究相反的情况：内潮如何被地转涡折射，以及这种不稳定的潮汐折射如何影响SWOT的测量，SWOT是未来的美国-法国卫星高度计，加拿大也将对其做出贡献。第二个方向将研究当地转流撞击波纹底部时，内波是如何损失能量的，以及这些内波最终是如何消散这种能量的。我们的假设是，内波与深层水跃(可以被描述为水下瀑布)相互作用，以加强深层的破碎、消散和混合。我们将在二维和三维数值模拟中研究这一现象。第三个研究方向将是研究内波与小尺度地转流之间的相互作用，例如靠近海洋表面的小涡或海洋锋面。我们将研究在锋面上传播的波是如何破裂的，以及它们是如何从锋面提取能量的。我们还将进行一项理论研究，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。这项工作可能有助于揭示通过SWOT观察到的过程。

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.