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Impact of breaker type on wave dissipation on a natural beach

断路器类型对天然海滩波浪消散的影响

基本信息

批准号：
1736389
负责人：
Carmine Chickadel
金额：
$ 29.37万
依托单位：
University of Washington
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-09-01 至 2020-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1736389&HistoricalAwards=false
关键词：
Impact breaker type wave dissipation

项目摘要

Wave forcing is the largest energy flux into the surf zone, the shallow nearshore region where surface gravity waves are influenced by the presence of the seafloor, become unstable, and break. The dissipation of wave energy here results in important nearshore processes, including circulation, mixing, sediment transport, and storm surge. An important goal of the nearshore science community is to understand and predict the time and space variability of wave breaking in the surf zone with the aim of deriving and modeling wave forcing over broad areas and with adequate resolution to represent the time and space scales that occur. However, wave breaking is a nonlinear, episodic event that is difficult to capture in a bulk model. The action and forces resulting from wave breaking cause and influence a broad range of processes at the ocean margin including erosion at the shoreline, strong and often dangerous currents, storm surge and coastal flooding, damage to coastal structures, and maritime navigation. Details of wave breaking are still poorly understood although they are parameterized broadly in modeling. Thus, this work will advance understanding of the details of breaking, and results and data from this effort will be used for direct model improvement and testing. This project will fund a graduate student whose dissertation will be focused on analysis and publication of the wave breaking data and it will develop presentations and activities showcasing wave research to the public during the annual outreach activities organized by the University of Washington and the Pacific Science Center.The project will analyze existing remote sensing data collected in the surf zone at the U.S. Army Corps of Engineers (USACE) Field Research Facility (FRF) at Duck, NC. Observations included thermal (infrared, IR), visual, and lidar remote sensing of the ocean waves propagating toward the shore. These data captured information covering a wide range of wave conditions. The aim of the data analysis is to analyze infrared imagery and lidar profiles of the waves to characterize their motion, the way waves break, and parameterize wave energy loss during the breaking process (wave dissipation). The identified need for improving nearshore models is to account for dissipation due to variable wave breaking type in the surf zone (i.e. spilling versus plunging breakers), how wave geometry and parameterizations of the wave physics compare with observations, and how those differences affect our ability to use remote sensing to estimate wave forcing remotely. Existing wave roller and bore-type models commonly used to estimate wave breaking dissipation assume steady state conditions that are violated at the break point where breaking waves form and plunging waves can occur. The inability of these parameterizations to account for the extra dissipation by plunging waves will bias modeling and efforts to remotely measure wave dissipation and wave forcing. Here, a new infrared-based remote sensing technique will be utilized, that has shown skill to remotely characterize individual breaking waves within the surf zone, but has not been tested near the breakpoint. Extension and modification of the method to account for breaking wave type will provide definitive insight into wave breaking, and provide a transformative observational tool that could be used observe breaking waves remotely.

波浪强迫是进入冲浪区的最大能量通量，在浅海近岸区域，表面重力波受到海底存在的影响，变得不稳定并破裂。波浪能的耗散导致了重要的近岸过程，包括环流、混合、输沙和风暴潮。近岸科学界的一个重要目标是了解和预测冲浪区波浪破碎的时间和空间变化，目的是在大范围内推导和模拟波浪强迫，并以足够的分辨率来表示发生的时间和空间尺度。然而，波浪破碎是一个非线性的、偶发的事件，很难在整体模型中捕捉到。波浪破碎所产生的作用和力量导致并影响了海洋边缘的一系列过程，包括海岸线的侵蚀、强大且往往危险的洋流、风暴潮和沿海洪水、对沿海结构的破坏以及海上航行。波浪破碎的细节仍然知之甚少，尽管它们在建模中被广泛地参数化。因此，这项工作将促进对断裂细节的理解，并且来自这项工作的结果和数据将用于直接的模型改进和测试。该项目将资助一名研究生，其论文将集中于波浪破碎数据的分析和出版，并将在华盛顿大学和太平洋科学中心组织的年度外展活动期间向公众展示波浪研究的演讲和活动。该项目将分析位于北卡罗来纳州达克的美国陆军工程兵团（USACE）野外研究设施（FRF）在冲浪区收集的现有遥感数据。观测包括热（红外，IR），视觉和激光雷达遥感海浪向海岸传播。这些数据捕获的信息涵盖了广泛的波浪条件。数据分析的目的是分析波的红外图像和激光雷达剖面，以表征波的运动，波的破碎方式，并参数化波在破碎过程中的能量损失（波耗散）。改进近岸模式的明确需求是考虑由于冲浪区不同的波浪破碎类型（即溢出浪与俯冲浪）造成的耗散，波浪几何和波浪物理的参数化如何与观测相比较，以及这些差异如何影响我们使用遥感来远程估计波浪强迫的能力。通常用于估计破波耗散的现有波浪滚子和钻孔型模型假定在破波形成和俯冲波可能发生的断点处不存在稳态条件。由于这些参数化不能解释下坠波造成的额外耗散，这将影响模拟和远程测量波耗散和波强迫的努力。在这里，将使用一种新的基于红外的遥感技术，该技术已显示出远程表征冲浪区内单个破碎波的技术，但尚未在断点附近进行测试。对该方法进行扩展和修改，以解释破碎波的类型，将为波浪破碎提供明确的见解，并提供一种可用于远程观测破碎波的变革性观测工具。