Quantifying Energy Dissipation From Breaking Waves Using Time-Varying Properties of Whitecap Foam

这项拟议研究的目标是开发一种遥感技术，以量化破碎海浪造成的能量损失。这项工作的动机是波浪破碎在增强海-气界面上的热量、质量、动量和能量交换方面所起的基本作用。此外，由于断裂强度参数的巨大变化，现有的遥感技术仍然高度不确定，这促使需要开发替代的遥感技术。预计拟议的遥感技术将有助于增强我们关于波浪破碎和能量耗散的基本知识，这对于了解气溶胶产生和气体交换是重要的。此外，遥感新技术隐含地考虑了逐波的波浪尺度和破裂强度，这可以为海浪的详细建模提供有价值的信息。这项研究的影响将通过本科生实习生参与实验室实验来进一步扩大，以帮助收集数据和进行初步分析。该项目团队将参加由桦树水族馆主办的公共外展讲座系列活动。遥感技术将利用高速和高分辨率的数字图像，记录主动波浪破碎过程中白色泡沫的时间变化特性，并将通过一系列利用海水和破碎波包进行的良好控制的实验室实验进行验证。目前的遥感技术依赖于测量破碎波速度来估计破碎波能量耗散，但是，关键的是，关于测量破碎波速度的最合适的方法，文献中缺乏共识。这对断裂强度参数的估计有直接影响，据报道，该参数的变化幅度为4个数量级。开发一种新的遥感技术将为目前的方法提供一种平行的办法。将寻求以下关键问题的答案：1)能否使用高分辨率和高速数字摄影来量化逐浪破碎过程中的能量消耗？2)利用线性波浪叠加产生的破碎波开发的新遥感技术是否可以应用于风力引发的破碎波？3)利用现有的海面图像数据集，新的遥感技术能否应用于风力引发的海域的破碎波？拟议的研究将包括实验室实验和对现有海面图像数据库的分析，以开始估计单个破碎海浪的能量消耗。实验室实验将基于对斯克里普斯海洋研究所33米玻璃波航道和40米风浪航道中的破碎波的观测。重要的是，这两个波浪通道的使用将确保在广泛的尺度上产生破碎波，并以不同的强迫机制(波-浪相互作用和风切变应力)产生破碎波。白盖泡沫、气泡羽流和波能将被监测，以监测通过下降式破碎器的溢出情况，使用俯视相机监测表面白盖特性，使用侧视相机监测气泡羽流特性，并使用波动计准确表征破碎引起的能量耗散。这一综合实验方法将为发展遥感技术提供必要的数据，以便在未来规划的实地研究中使用。

The goal of the proposed research is to develop a remote sensing technique to quantify the energy lost by breaking waves. The work is motivated by the fundamental role that wave breaking plays in enhancing the exchange of heat, mass, momentum and energy across the air-sea interface. Furthermore, existing remote sensing techniques remain highly uncertain due to large variations in the breaking strength parameter, motivating the need to develop alternative remote sensing techniques. It is anticipated that the proposed remote sensing technique will help enhance our fundamental knowledge of wave breaking and energy dissipation, which is important for the understanding of aerosol production and gas exchange. Furthermore, the remote new sensing technique implicitly accounts for both wave scale and breaking intensity on a wave-by-wave basis, which can provide valuable information for detailed modeling of ocean waves. The impact of the study will be further broadened by the participation of undergraduate interns in the laboratory experiments to help with data collection and preliminary analysis. The project team will participate in the public outreach lecture series hosted by the Birch Aquarium.The remote sensing technique will utilize high-speed and high resolution digital images of the time-varying properties of whitecap foam during active wave breaking and will be validated against a series of well-controlled laboratory experiments using seawater and breaking wave packets. Present remote-sensing techniques rely on measuring breaking wave speed to estimate breaking wave energy dissipation, but, critically, there is a lack of consensus in the literature regarding the most appropriate way to measure breaking wave speed. This has direct implications for estimates of the breaking strength parameter, which has been reported to vary by 4 orders of magnitude. Development of a new remote sensing technique will offer a parallel approach to the present methodology. Answers to the following key questions will be sought: 1) Can high-resolution and high-speed digital photography be used to quantify energy dissipation during wave breaking on a wave-by-wave basis? 2) Can the new remote sensing technique, developed using breaking waves generated by linear wave superposition, be applied to wind-driven breaking waves? 3) Using existing datasets of sea surface images, can the new remote sensing technique be applied to breaking waves in wind-driven seas? The proposed research will involve a combination of laboratory experiments and analysis of an existing database of sea surface images to begin to estimate energy dissipation for individual breaking waves. The laboratory experiments will be based on observations of breaking waves in both the 33 meter glass wave channel and the 40 meter wind-wave channel at the Scripps Institution of Oceanography. Importantly, the use of these two wave channels will ensure breaking waves are generated across a wide range of scales and with different forcing mechanisms (wave-wave interaction and wind shear stress). Whitecap foam, bubble plume and wave energetics will be monitored for spilling through plunging breakers using a downward looking camera to monitor the surface whitecap properties, a sideward looking camera to monitor bubble plume characteristics and wave gauges to accurately characterize energy dissipation due to breaking. This comprehensive experimental approach will provide the necessary data to develop the remote sensing technique for use in future-planned field studies.