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

利用 Whitecap 泡沫的时变特性量化破碎波的能量耗散

• 批准号: 1434866
• 负责人: Grant Deane
• 金额: $ 70.21万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-10-01 至 2019-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1434866&HistoricalAwards=false
• 关键词: Quantifying; Energy; Dissipation; Breaking; Waves

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.

拟议研究的目标是开发一种遥感技术，以量化破碎波损失的能量。这项工作的动机是波浪破碎在加强空气-海洋界面的热量、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变化很大，现有的遥感技术仍然具有高度的不确定性，因此需要开发替代遥感技术。预计所提出的遥感技术将有助于提高我们对波浪破碎和能量耗散的基本认识，这对了解气溶胶产生和气体交换非常重要。此外，这种新的遥感技术隐含地考虑了海浪尺度和海浪破碎强度，可以为海浪的详细建模提供有价值的信息。本研究的影响会因本科生实习生参与实验室实验而进一步扩大，以协助收集资料及初步分析。项目团队将参加由桦树水族馆举办的公众推广系列讲座。该遥感技术将利用高速、高分辨率的数字图像，记录活跃破波过程中白浪泡沫的时变特性，并将通过一系列控制良好的实验室实验，利用海水和破波包进行验证。目前的遥感技术依赖于测量破碎波的速度来估计破碎波的能量耗散，但是，关键的是，在文献中缺乏关于测量破碎波速度的最合适方法的共识。这对断裂强度参数的估计有直接影响，据报道，断裂强度参数的变化幅度为4个数量级。发展一种新的遥感技术将提供一种与目前的方法平行的方法。本文将寻求以下关键问题的答案：1)能否利用高分辨率和高速数码摄影来量化破波过程中逐波的能量耗散？2)利用线性波叠加产生的破碎波开发的新型遥感技术能否应用于风力破碎波？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驱动海域的破浪？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相结合，以开始估计个别破碎波的能量耗散。实验室实验将基于对斯克里普斯海洋研究所33米玻璃波通道和40米风浪通道的破波观测。重要的是，这两种波浪通道的使用将确保在广泛的尺度上产生破碎波，并具有不同的强迫机制（波浪-波浪相互作用和风切变应力）。白浪泡沫、气泡羽流和波浪能量学将通过一个向下看的摄像机来监测表面白浪的特性，一个侧面看的摄像机来监测气泡羽流的特性，波浪计来准确地描述由于破裂而产生的能量耗散。这种全面的实验方法将为发展遥感技术提供必要的数据，以供将来规划的实地研究使用。