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

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定量化。通过对实验室表面图像的分析，将测量波浪边界的表面流和小尺度的破波。波边界层被定义为深度为(kp) -1阶的顶层。KP为优势风浪的波数。该方法克服了在边界层中设置传感器的问题，这是早期测量的一个困难。表面波和近表面湍流也将同时测量。这将使接触表面流、波浪和湍流之间的相互作用成为可能，从而量化这些量以进行参数化。近年来对自由表面湍流的研究表明，壁面边界层湍流与自由表面湍流有着根本的区别。在海上，风吹过海面，产生波浪和切变流。由于这些高能波的存在，海洋表层更为复杂。破波和海面漂移可以相互促进。由于克雷克-莱博维奇跨度不稳定性，表面剪切流本质上是不稳定的。朗缪尔环流增加了垂直混合，减少了地表切变。一个简单的壁面湍流类比是否足以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，关键是要观测关键的表面量，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