Infrared Remote Sensing of Cooling Whitecap Foam to Quantify Wave Breaking and Aeration

不论是在公海还是在海气相互作用过程中，波浪破碎都起着至关重要的作用。能量和动量通过风浪的产生从大气转移到海洋，最终被海浪耗散。由此产生的上层海洋的湍流导致混合，而近岸的动量转移可以推动洋流。为了更好地理解波浪破碎的影响，需要提高对波浪破碎过程中气泡和泡沫形成过程的理解。本项目的目标是开发和利用遥感技术，利用破碎过程中冷却残余泡沫的热特征，研究气泡羽流的形成和相关的破波能量耗散。将进行大型室外实验室试验，评估现场尺度破波技术，探讨破波类型、破波强度和气泡分布对破波技术的影响。研究人员假设，从破裂开始到残余泡沫开始冷却的时间提供了气泡羽流衰减时间和深度的度量，可用于确定气泡特征和评估与波能量耗散率相关的现有羽流模型。先前的研究结果表明，泡沫冷却时间可以用来映射气泡羽流深度的空间变异性，从而提供空间变化的气泡羽流体积。该项目将使用热红外（IR）图像和辅助测量来调查和进一步建立这些关系。由此产生的远程量化气泡羽流特性和波浪破碎引起的能量耗散的能力将为调查和理解公海和冲浪区波浪破碎驱动的海气相互作用过程提供一种新的变动性工具。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Wave breaking plays a critical role in air-sea interaction processes in both the open ocean and the surf zone. Energy and momentum transferred from the atmosphere to the ocean through wind-wave generation is ultimately dissipated by waves. The resulting turbulence in the upper ocean causes mixing, and in the nearshore momentum transfer can force currents. Improved understanding of the bubble and foam formation processes during wave breaking is needed to better understand the impacts of wave breaking. The goal of this project is to develop and utilize a remote sensing technique to study bubble plume formation and associated wave breaking energy dissipation by exploiting the thermal signature of cooling residual foam left behind by the breaking process. A large-scale, outdoor laboratory experiment will be conducted to evaluate the technique for field-scale breaking waves and explore the effect of wave breaking type, breaking strength, and bubble distribution.The investigators hypothesize that the time from when breaking begins to when the residual foam starts to cool provides a measure of both the bubble plume decay time and depth, which can be used to determine bubble characteristics and evaluate existing plume models related to the wave energy dissipation rate. Prior results indicate that the foam cooling time can be used to map the spatial variability of bubble plume depth and thus provide the spatially varying bubble plume volume. This project will use thermal infrared (IR) imagery and ancillary measurements to investigate and further establish these relationships. The resulting ability to remotely quantify bubble plume properties and energy dissipation due to wave breaking will provide a new and transformative tool for investigating and understanding the air-sea interaction processes driven by wave breaking in the open ocean and the surf zone.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.