Proof of Concept: Exploiting Cooling Whitecap Foam to Quantify Wave Breaking Dissipation

该项目是一个概念验证，通过观察破碎波及其产生的泡沫的红外图像中的热特征，利用遥感方法来确定波浪能量损失的数量。当波浪破裂时，能量被耗散，动量从波浪转移到表面水流。这些过程在公海和冲浪区都是至关重要的。波浪破碎能量耗散的量化直接关系到实际海况预报所用的波浪预报模型和风暴对沿海地区的影响。破碎波产生的气泡是中高风速下气体传递的主要机制。气泡也有助于海洋气溶胶的形成，当泡沫中的气泡在表面破裂时，会产生喷雾液滴。波浪破碎产生的泡沫会增加太阳辐射的反射率，从而影响地球？反照率。泡沫也增加了微波发射率，这影响了空间辐射计对风速的测量。这一概念验证的成功将为空气-水界面的动量、气体和热量以及全球遥感应用开辟一个新的研究方向。该项目将培养一名博士后，该博士后将参与研究的各个方面，并将有两名本科生参与夏季实验。本科生将通过华盛顿太空资助暑期本科生研究计划（SURP）参加，PI过去曾通过该计划指导学生。PI将要求来自弱势群体的学生，这是该项目所强调的。该项目还将加强研究基础设施，使最近收购的风浪设施全面投入使用。该研究小组的长期目标是开发和利用一种遥感技术，通过利用破碎过程中留下的冷却残余泡沫的独特热特征来推断波浪破碎造成的能量耗散。该方法基于最初的想法，即从破裂开始到残余泡沫开始冷却的时间可以用作气泡羽状物衰减时间的代理，而气泡羽状物衰减时间又可以用来参数化单个破裂波所消耗的能量。由此产生的远程量化波浪破碎引起的能量耗散的能力，将为调查和理解由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革性工具。利用泡沫的冷却特征来量化破裂的一个关键要求是，冷却的开始不受自然变异性表面活性剂的影响。这个项目的范围仅限于确定表面活性剂对冷却泡沫的影响，作为开发这个新的和有前途的想法的必要的概念证明。第一步的成功可能会导致更完整的研究，利用白浪泡沫的冷却来量化破波耗散。

This project is a proof of concept for a remote sensing method to determine the amount of wave energy lost due to wave breaking, by observing the thermal signatures in the infrared imagery of the breaking wave and the foam it produces. When waves break, energy is dissipated and momentum is transferred from waves to surface currents. These processes are critically important both in the open ocean and in the surf zone. Quantifying the energy dissipation due to wave breaking is directly relevant to wave prediction models used for operational sea-state forecasting and the impact of storms on coastal regions. Bubbles generated by breaking waves are the primary mechanism for gas transfer at moderate to high wind speed. Bubbles also contribute to marine aerosol formation through spray droplets produced when bubbles in foam burst at the surface. Foam generated by wave breaking has increased reflectivity of solar radiation that can affect the Earth?s albedo. Foam also has increased microwave emissivity, which impacts space borne radiometer measurements of wind speed. Success in this proof of concept will open a new research direction with implications for momentum, gas, and heat across the air-water interface and global remote sensing applications. The project will contribute to the training of a postdoctoral fellow who will participate in all aspects of the work and involve two undergraduates in the summer experiments. The undergraduates will participate via the Washington Space Grant Summer Undergraduate Research Program (SURP), through which the PI has mentored students in the past. The PI will request students from an underrepresented group, which the program emphasizes. The project will also enhance research infrastructure by making a recently acquired wind-wave facility fully operational.The long-term goal of this research team is to develop and utilize a remote sensing technique to infer energy dissipation due to wave breaking by exploiting the unique thermal signature of cooling residual foam left behind by the breaking process. The approach is based on the original idea that the time from when breaking begins to when the residual foam starts to cool can be used as a proxy for the bubble plume decay time, which in turn can be used to parameterize the energy dissipated by an individual breaking wave. The resulting ability to remotely quantify 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. A critical requirement to exploit the cooling signature of foam to quantify breaking is that the onset of cooling is not affected by the natural variability surfactants. The scope of this project is limited to determining the effect of surfactants on cooling foam as a necessary proof of concept to developing this new and promising idea. Success in this first step could lead to a more complete investigation, which exploits the cooling of whitecap foam to quantify wave breaking dissipation.