Observing Wind Induced Near-Surface Currents within the Water Wave Boundary

0118028 Zhang本研究旨在通过先进的观测实验提高这些海洋表面参数的量化。通过分析实验室获得的表面图像，将测量波浪边界和小尺度波浪破碎处的表面流。波边界层被定义为（kp）-1阶深度内的顶层。kp是主导风浪的波数。本文提出的方法将克服在边界层中设置传感器的问题，这是早期测量的一个困难。同时还将测量表面波和近地表湍流。这将使人们有可能访问表面电流，波浪和湍流之间的相互作用，量化这些参数。最近的自由表面湍流研究表明，有壁边界层湍流和自由表面湍流之间的根本区别。在海上，风吹过海洋表面，产生波浪和剪切流。由于这些高能波的存在，海洋表层更加复杂。波浪破碎和表面漂移可以相互增强。由于Craik-Leibovich展向不稳定性，表面剪切流是固有的不稳定。朗缪尔环流增加了垂直混合，减少了表面剪切。简单的壁湍流类比是否能充分地表示自由表面边界层的动力学是值得怀疑的。为了评估不同海洋表面过程的贡献，关键是要观察关键的表面量，如表面波、表面流、表面湍流、波浪破碎率和垂直输送

0118028 ZhangThis study is aimed at improving the quantification of these ocean surface parameters through advanced observational experiments. From analysis surface images from the laboratory, the surface currents in the wave boundary and small-scale wave breaking will be measured. A wave boundary layer is defined as a top layer within a depth of order (kp) -1 . kp is wavenumber of dominant wind waves. The method developed here will overcome the problem of having sensor in the boundary layer, a difficulty of early measurements. The surface waves and near surface turbulence will also be measured at the same time. These will make it possible to access the interactions among surface currents, waves, and turbulence, to quantify these quantities for parameterization. Recent free surface turbulence studies have showed there are fundamental differences between wall boundary layer turbulence and free surface turbulence. At sea, wind blows over the ocean surface generating waves and shear currents. The ocean surface layer is more complex due to the existence of these energetic waves. Wave breaking and surface drift can enhance one another. The surface shear currents are inherently unstable due to Craik-Leibovich span-wise instability. The Langmuir circulations increase the vertical mixing which reduces the surface shear. It is questionable that a simple wall turbulence analogy would adequately represent the dynamics of a free surface boundary layer. To assess the contributions from different ocean surface processes, it is critical to observe key surface quantities, such as surface waves, surface current, surface turbulence, rate of wave breaking, and vertical transport