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

该项目是对一种遥感方法的概念验证，该方法通过观察破碎波及其产生的泡沫的红外图像中的热特征来确定由于波浪破碎而损失的波能。当波浪破裂时，能量被消散，动量从波浪转移到表面洋流。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用于海况预报业务的波浪预报模型和风暴对沿海地区的影响。在中高风速下，破碎波产生的气泡是气体传输的主要机制。气泡还通过泡沫中的气泡在表面破裂时产生的喷雾液滴促进海洋气溶胶的形成。海浪破碎产生的泡沫增加了太阳辐射的反射率，这可能会影响地球？S反照率。泡沫还增加了微波发射率，这会影响星载辐射计对风速的测量。这一概念验证的成功将开启一个新的研究方向，对空气-水界面和全球遥感应用中的动量、气体和热量产生影响。该项目将有助于培养一名博士后研究员，他将参与工作的所有方面，并让两名本科生参与暑期实验。本科生将通过华盛顿太空助学金暑期本科生研究项目(SURP)参与，过去PI曾通过该项目指导学生。PI将要求学生来自代表人数不足的群体，这是该计划强调的。该项目还将通过使最近获得的风浪设施完全投入使用来加强研究基础设施。该研究团队的长期目标是开发和利用一种遥感技术，通过利用波浪破碎过程中留下的冷却残余泡沫的独特热特征来推断由于波浪破碎而造成的能量耗散。该方法基于从破裂开始到残余泡沫开始冷却的时间可以作为气泡羽流衰减时间的替代，而气泡羽流衰减时间又可以用来对单个破裂波所耗散的能量进行参数化。由此产生的对波浪破碎造成的能量耗散进行远程量化的能力将为研究和理解由波浪破碎在公海和海浪带驱动的海-气相互作用过程提供一个新的变革性工具。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化的表面活性剂的影响。该项目的范围仅限于确定表面活性剂对冷却泡沫的影响，作为开发这一新的和有希望的想法的必要概念证明。这第一步的成功可能会导致更全面的研究，利用白云泡沫的冷却来量化波浪破碎消散。

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.