An experimental study of the structure of the air-flow above ocean surface waves

近年来，在量化大气和海洋之间的动量交换方面取得了相当大的进展。表面波在海气动量通量中的作用已经很好地确定，但我们对气流动力学的物理理解仍然不完整。这阻碍了我们开发更好的基于物理的参数化的能力，以更好地预测天气和海况，特别是在大风和极端条件下。在这个项目中，该团队提出了对现有数据集的进一步分析，该数据集包括在实验室中在短表面波上方的近地表气流中进行的广泛的高分辨率2D速度测量。预计这项工作将导致更好地了解详细的，小规模的物理在海气界面，这是必要的建立准确的耦合（海洋-大气和海洋-波浪-大气）模型的天气和气候。此外，本研究的数据产品可能会被证明是有用的比较与当前和未来的大涡模拟（LES）和直接数值模拟（DNS）。该项目将支持博士学位。表面波在耦合的大气和海洋边界层动力学中的重要性是公认的。相反，这种现象的大气对应物，即由气流分离产生的近地面大气湍流与表面波的耦合，受到的关注较少。到目前为止，我们的不完全理解的近地面湍流（波或剪切产生）和表面波之间的耦合仍然是一个路障，以改进的海气动量通量参数化的发展。近地表大气边界层中的湍流部分是由破碎引起的气流分离产生的，因此，该团队将特别关注湍流动能（TKE）和表面波之间的相干性和耦合。建议使用的数据涵盖波龄Cp/u#8727;从1.4（非常年轻的波）到66.7（老波）不等，因此涵盖了大范围的现场相关条件。该团队建议通过波锁定和相位锁定坐标系实现的三重速度分解来提取湍流和波相干速度场。然后，该团队将评估湍流动力学平衡，他们将特别关注相位相干湍流和表面波之间的相互作用。

In recent years, considerable progress has been made in quantifying the exchange of momentum between the atmosphere and the ocean. The role of surface waves on the air-sea momentum flux is well established but our physical understanding of the airflow dynamics remains incomplete. This impedes our ability to develop improved physically based parameterizations for better weather and sea state predictions, especially in high winds and extreme conditions. In this project, the team proposes the further analysis of an existing dataset consisting of extensive high resolution 2D velocity measurements taken in the laboratory in the near surface airflow above short surface waves. It is anticipated that this work will lead to an improved understanding of the detailed, small scale physics at the air-sea interface that is necessary to build accurate coupled (ocean-atmosphere and ocean-wave-atmosphere) models of weather and climate. Furthermore, data products from this study will likely prove useful for comparison with current and future Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS). This project will support the Ph.D. work of a graduate student.The importance of the surface wave in the dynamics of the coupled atmospheric and oceanic boundary layers is well recognized. In contrast, the atmospheric counterpart of this phenomenon, that is the coupling of the near surface atmospheric turbulence generated by airflow separation with the surface waves, has received less attention. To date, our incomplete understanding of the coupling between the near surface turbulence (wave or shear generated) and the surface waves remains a roadblock to the development of improved air-sea momentum flux parameterizations. Turbulence in the near surface atmospheric boundary layer is in part generated by breaking-induced airflow separation, the team thus will focus in particular on the coherence and coupling between the turbulent kinetic energy (TKE) and the surface waves. The data proposed to use covers wave ages Cp/u∗ varying from 1.4 (very young waves) to 66.7 (old waves) thus encompassing a large range of field-relevant conditions. The team proposes to extract turbulent and wave-coherent velocity fields by means of a triple velocity decomposition made possible by a wave- and phase-locked coordinate system. The team will then evaluate the turbulent kinetic balance and they will especially focus on the interaction between phase coherent turbulence and the surface waves.