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

利用光学测高法进行大规模海洋环流与涡流、急流和内波相互作用的实验

• 批准号: 0648575
• 负责人: Peter Rhines
• 金额: $ 40.59万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-15 至 2011-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0648575&HistoricalAwards=false
• 关键词: Experiments; interaction; Large; Scale; Oceanic

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.

Abstractoce-0648575这是对海洋循环及其小规模但充满活力的成分的实验研究。使用新发现的实验室遥感技术，我们称之为光学高度测定，将研究循环与涡流，内部波和类似喷射的流动浓度的相互作用。北大西洋次极的循环是特别的重点。在那里，已经确定了几种外部循环源（风，深对流和从北部和南部的潮流入侵）。一般循环的内部来源，即潜在涡度（PV）场的涡流搅拌，将在详细的动力学实验中使用具有重要底层地形特征的理想化海盆进行详细的动态实验。平行数值实验将使用分层的静水海洋模型进行。 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），内部波和对流与分层的鸡肉流动相互作用。光学高度学利用旋转流体表面的抛物线形状作为牛顿望远镜，从而使整个表面高程场的成像均高于1微米的分辨率，并横向分辨率高。通过将彩虹图像投射到表面上，我们恢复了准确的海拔，速度和涡度场。分层实验也将使用内部层厚度传感，也将使用光学上。第四组实验需要特别评论。这些高纬度海洋的数值建模很少结合非静态，非地球形动力学，在这一领域，3维实验室实验可以具有令人印象深刻的空间分辨率。借助我们新的实验能力，可以探索盆地规模循环和内部波，前线，对流和三维湍流之间的来回相互作用。已知所有这些都在亚极海洋中很强。当流动横穿显着的底部地形时，液压“下坡喷射”形式将研究它们与中尺度旋风涡流的相互作用；将探索内波辐射和被隔离涡流和涡流组合的捕获，边界层湍流和地质流动之间的能量的来回转换也将探索。IntellectualFure：潜在的涡旋动力学是关键，是基本的海洋和大气循环范围理论。它表达了涡流和一般循环之间的强大关系。开发和利用这种“ PV思维”既重要，既重要，既是基础科学，又是对全球气候模型的重要模拟的支持，这些模型无法解决控制PV场的所有详细高纬度过程。Boader的影响：了解海洋气候系统对于全球热身及其在慢速慢速循环中的预测效应而言至关重要。大多数气候模型随着温室气体的增加而运行，在本世纪，大西洋子午线推翻的放缓高达40％。如果仔细观察，亚极大的大西洋的动力学是这种效果的关键组成部分。侧向回旋循环的相互作用与全球子午倾覆循环相互作用。除了气候研究之外，基本PV动力学的这项工作还影响了我们对大气循环以及其他行星气氛的理解。在全球变暖下，它与地球生态系统的命运有着牢固的关系。