Environmental, Industrial and Climatological Impacts of Internal Gravity Waves

所有天然存在的流体都是分层的，这意味着它们的有效密度随高度而降低。 这种减少可以是迅速的和局部的，如在海洋的温跃层或在大气逆温层。 或者是渐进的，就像在平流层。 在这样的分层流体中流动的是内波，内波由于浮力而移动。 由于它们输送能量和动量，并在破碎时引起湍流，波浪对气候，环境，空中交通，渔业，海上石油和其他行业产生重要影响。 然而，对局部内波的动力学知之甚少。 通过三个相互关联的研究流，我建议进行实验室实验和数值模拟，以开发预测模型的演变和大气和海洋内波包的崩溃。 我将发展理论，辅以模拟，以研究对局部小振幅波包引起的流动的响应。 我最近已经证明，在没有破碎的情况下，垂直传播的波包会发射出长的内波，在很宽的水平范围内重新分配波包的动量。 气候模式，使用物理学来预测内波的动量传输，没有考虑到这种影响，因此错误地预测了破碎区域的空间范围。 包括大振幅的影响，我将检查后的波包本身的演变所引起的长波的影响，并将预测风加速时，二维和三维波包最终打破在大气中。 这项工作将用于改进气候模式中内波的表示。 我也将使用这种理论方法来预测质量运输的局部内波在厚界面，与意图获得更好的了解污染物和营养物质的横向分散有关的海洋温跃层。 另一个研究流将研究由于参数次谐波不稳定性（PSI）而导致的厚界面处内部波包的分解，这种机制以前只研究过周期波，最近才研究过波束。由于PSI的波包分解的这一更现实的检查将提供从大到小尺度的能量级联的洞察力，结果将被投在海洋环流模式中使用的混合参数化方案中使用。 第三个研究流将进行实验室实验和模拟，以研究大振幅界面内波在复杂地形上浅滩时的演变，重点关注能量再分配、沉积物再悬浮和推移质输运。 这项工作将用于评估与开发和维护沿着洋底的海上石油平台和管道有关的危险。

All naturally occurring fluids are stratified, meaning that their effective density decreases with height. The decrease can be rapid and localized, as at a thermocline in the ocean or at an atmospheric inversion. Or it can be gradual, as in the stratosphere. Propagating within such stratified fluids are internal waves, which move due to buoyancy forces. Because they transport energy and momentum and cause turbulence where they break, the waves have important consequences for climate, environment, air traffic, fisheries, offshore oil and other industries. However, relatively little is known about the dynamics of localized internal waves. Through three interrelated research streams, I propose to perform laboratory experiments and numerical simulations to develop predictive models for the evolution and breakdown of atmospheric and oceanic internal wave packets. I will develop theory complemented by simulations to examine the response to flows induced by localized small amplitude wave packets. I have recently shown that, without breaking, vertically propagating wave packets launch long internal waves that redistribute the momentum of the packet over a wide horizontal extent.  Climate models, which use heuristics to predict momentum transport by internal waves, do not account for this effect and so incorrectly predict the spatial extent of the breaking region.  Including large-amplitude effects, I will examine the influence of the induced long waves upon the evolution of the wave packets themselves and will predict where winds are accelerated when two- and three-dimensional wavepackets ultimately break in the atmosphere.  This work will be applied to improve the representation of internal waves in climate models. I will also use this theoretical approach to predict mass transport by localized internal waves at a thick interface, with the intent of obtaining a better understanding of the lateral dispersion of pollutants and nutrients about the oceanic thermocline. Another research stream will examine the breakdown of internal wave packets at thick interfaces due to parametric subharmonic instability (PSI), a mechanism that has previously been examined only for periodic waves and more recently for wave beams. This more realistic examination of wave packet breakdown due to PSI will provide insight into the energy cascade from large to small scales, a result that will be cast for use in mixing parameterization schemes used in ocean general circulation models. A third research stream will perform laboratory experiments and simulations to examine the evolution of large amplitude interfacial internal waves as they shoal upon complex topography, with a focus upon energy redistribution, sediment resuspension and bedload transport. This work will be applied to assess hazards associated with the development and maintenance of offshore oil platforms and pipelines that run along the ocean floor.