Experiments on the interaction of Large-Scale Oceanic Oirculation with Eddies, Jets and Internal Waves using Optical Altimetry

这是一项关于海洋环流及其小尺度但高能成分的实验研究。利用一种新发现的实验室遥感技术，我们称之为光学测高，将研究环流与涡流、内波和喷流状浓度的相互作用。亚极地北大西洋的环流是特别关注的焦点。在那里，已经确定了几个外部环流来源(风、深对流和来自南北的洋流的入侵)。作为大气环流的内部来源，位涡(PV)场的涡旋搅动将在具有显著海底地形特征的理想化洋盆的详细动力学实验中进行评估。将使用分层的、流体静力海洋模型进行并行的数值实验。计划进行的具体试验是：(1)将一般环流集中到急流和锋面与稳定流相互作用的海底地形；(2)由准地转时变流动驱动的大规模环流，绕过复杂的海底脊线和海山；(3)涡旋地形与密度层结的相互作用，包括斜压不稳定沿岸流的生命周期；以及(4)内波和对流与分层营养水流的相互作用。光学高度计利用旋转流体表面的抛物线形状作为牛顿望远镜，允许以优于1微米的分辨率和高横向分辨率成像整个表面高度场。通过在表面投射彩虹图像，我们恢复了精确的高度场、速度场和涡量场。分层实验将使用内层厚度传感，也是光学的。第四组实验需要特别说明。对这些高纬度海洋的数值模拟很少结合非静力、非地转动力学，在这一领域，三维实验室实验可以具有令人印象深刻的空间分辨率。利用我们的新实验能力，可以探索盆地尺度环流与内波、锋面、对流和三维湍流之间的往返相互作用。众所周知，它们在亚极地海洋中都很强。当水流穿过重要的海底地形时，将形成水力“下坡喷流”，将研究它们与中尺度气旋性涡旋生成的相互作用；将探索内波辐射和孤立的涡旋和涡旋组合的捕获，以及边界层湍流和地转流之间的能量来回转换。它表达了涡旋活动和大气环流之间的强大联系。发展和利用这种“光伏思维”对于基础科学和支持重要的全球气候模型模拟都是重要的，因为它不能解决控制光伏场的所有详细的高纬度过程。广泛的影响：了解海洋气候系统对于全球变暖这一更大的问题及其对减缓全球海洋循环的预期影响至关重要。大多数在温室气体增加的情况下运行的气候模型发现，本世纪大西洋经向翻转的速度减缓了40%。如果仔细观察，亚极地大西洋的动态是这种效应的关键组成部分。横向涡旋环流与全球经向翻转环流相互作用。除了气候研究，这项关于基本光伏动力学的工作还影响到我们对大气循环以及其他行星大气的理解。它与全球变暖下地球生态系统的命运密切相关。

ABSTRACTOCE-0648575This is an experimental investigation of the oceanic circulation and its small-scale, yet energetic, components. Using a newly discovered laboratory remote-sensing technique which we call optical altimetry, the interaction of the circulation with eddies, internal waves and jet-like concentrations of flow will be studied. The circulation of the subpolar North Atlantic Ocean is the particular focus. There, several external sources of circulation have been identified (wind, deep convection, and incursion of currents from north and south). An internal source of general circulation, the eddy stirring of the potential vorticity (PV) field, will be evaluated in detailed dynamics experiments using idealized ocean basins with significant bottom topographic features. Parallel numerical experiments will be carried out using a layered, hydrostatic ocean model. The specific experiments planned are (i), the concentration of general circulation into jets and fronts with steady flow interacting bottom topography, (ii), large-scale circulation driven by quasi-geostrophic, time-variable flow over a field of complex seafloor ridges and seamounts, (iii), eddy-topography interaction with density stratification including the life-cycle of a baroclinically unstable coastal current and, (iv), internal waves and convection interacting with stratified, gesotrophic flows. Optical altimetry exploits the parabolic shape of the surface of a rotating fluid as a Newtonian telescope, allowing the entire surface elevation field to be imaged with better than 1 micron resolution, and high lateral resolution. By projecting a rainbow image on the surface, we recover accurate elevation, velocity and vorticity fields. Stratified experiments will use interior layer thickness sensing, also optically. The fourth set of experiments requires special comment. Numerical modeling of these high latitude oceans rarely incorporates non-hydrostatic, non-geostrophic dynamics, and in this area 3-dimensional lab experiments can have impressive spatial resolution. With our new experimental capability the back-and-forth interaction among basin-scale circulation and internal waves, fronts, convection and 3-dimensional turbulence can be explored. All are known to be strong in the subpolar oceans. Hydraulic 'down-slope jets' form as flow crosses significant bottom topography, and their interaction with mesoscale cyclonic eddy generation will be investigated; internal wave radiation and trapping by isolated vortices and vortex assemblages will be explored, as will the back-and-forth conversion of energy between boundary-layer turbulence and geostrophic flow.Intellectual Merit: Potential vorticity dynamics is the key, underlying field theory of thecirculation of oceans and atmosphere. It expresses powerful relationships between eddy activity and general circulation. Developing and exploiting this 'PV thinking' is important both as basic science, and as support for important simulations of global climate models, which cannot resolve all the detailed high-latitude processes which control the PV field.Broader impacts: Understanding the ocean climate system is of key importance to the largerproblem of global warming and its predicted effect in slowing the global ocean circulation. Most climate models run with increasing greenhouse gases find a slowing of the Atlantic meridional overturning, by as much as 40%, during this century. If one looks closely, the dynamics of the subpolar Atlantic is a crucial component of this effect. There is interaction of lateral gyre circulations interact with the global meridional overturning circulation. Beyond climate research, this work on basic PV dynamics impacts our understanding of circulations of the atmosphere, and the atmospheres of other planets. It has strong relationships with the fate of Earth's ecosystems under global warming.