Transient Rip Current Dynamics: Laboratory Measurements and Modeling of Surfzone Vorticity

瞬态裂谷流动力学：表面区涡度的实验室测量和建模

• 批准号: 1735460
• 负责人: Melissa Moulton
• 金额: $ 71.7万
• 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: 2017-09-15 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1735460&HistoricalAwards=false
• 关键词: Transient; Rip; Current; Dynamics; Laboratory

The nearshore region, valued as essential intertidal habitat and recreational grounds, is often compromised by pathogens and excess nutrient supply from terrestrial runoff. When an area becomes contaminated, beach closures, ecological disruption, and associated economic losses can result. Understanding the transport of materials throughout the nearshore region can have important implications for ecosystem and human health. Previous studies analyzing cross-shelf exchange suggest that transient rip currents are the dominant mechanism driving exchange between the surf zone and the inner shelf. Evidence also suggests that transient rip currents are generated from the coalescence of surf zone eddies, with short-crested waves serving as the source of rotation. This project will utilize a laboratory and numerical modeling to study the generation and evolution of surf zone eddies to form transient rip currents. The knowledge of mixing and exchange in the nearshore region will be significantly advanced through this study, which will have important implications for the transport of nutrients, larvae, and pollutants. In collaboration with National Oceanic and Atmospheric Administration scientists, simple predictors of transient rip currents will be developed to improve hazard forecasts for a broad range of environments. This is essential information for human safety as rip currents are the leading cause of fatalities and rescues on beaches. A graduate student will gain valuable training and education through involvement in this project. Outreach activities highlighting rip currents will be developed as a part of the O.H. Hinsdale Wave Research Laboratory Outreach Program seeking to broaden participation in Science, Technology, Engineering and Mathematics (STEM).This project seeks to establish a cradle-to-grave picture of the injection of eddies into the surf zone by short-crested wave breaking, coalescence to form larger eddies, and formation of transient rip currents. The overall objective is to determine if the surf zone can be treated as a two-dimensional turbulence box. This study will improve understanding of the dynamics of surf zone eddy generation and evolution leading to transient rip currents and associated cross-shelf exchange by addressing four specific hypotheses: 1) short-crested waves are an important vorticity source at short spatial and temporal scales, 2) smaller eddies coalesce to create bigger eddies, 3) surf zone eddy decay is controlled by bottom friction, and 4) eddies ejected outside of the surf zone onto the shelf deviate from the two-dimensional paradigm. Laboratory experiments will include in situ and remote (stereo visible and infrared) measurements of sea-surface-elevations and velocities for a range of wave heights, periods, and directional spreads. State-of-the-art numerical modeling will be used to guide laboratory sampling, to analyze dynamics for a range of conditions, and to assess the importance of frictional dissipation and three-dimensional circulation properties. If the surf zone can be treated as a forced two-dimensional turbulence box, simplified models with appropriate forcing can be established to advance the understanding of the role of the surf zone in land-to-sea transport.

近岸地区，被视为必不可少的潮间栖息地和娱乐场所，通常受到病原体和陆地径流过多的养分供应的损害。当某个地区被污染时，可能会导致海滩封闭，生态破坏以及相关的经济损失。了解整个近岸地区材料的运输可能对生态系统和人类健康具有重要意义。先前分析跨架交换的研究表明，瞬态撕裂电流是驱动冲浪区和内架之间的主要机制。证据还表明，瞬时撕裂电流是从冲浪区涡流的聚结中产生的，其短纹波作为旋转来源。该项目将利用实验室和数值建模来研究冲浪区域涡流的产生和演化，以形成瞬态撕裂电流。通过这项研究将显着提高近海地区混合和交换的知识，这将对养分，幼虫和污染物的运输具有重要意义。与国家海洋和大气管理科学家合作，将开发简单的瞬态撕裂电流预测指标，以改善广泛环境的危害预测。这是人类安全的重要信息，因为撕裂电流是海滩上死亡和救援的主要原因。研究生将通过参与该项目获得宝贵的培训和教育。将作为O.H.的一部分开发出突出撕裂电流的外展活动。 Hinsdale Wave研究实验室外展计划，旨在扩大科学，技术，工程和数学（STEM）的参与。本项目旨在通过短暂的波浪破裂，结合形成较大的涡流，并形成短暂的RIP Currents的形成，以建立将涡流注入冲浪区域的摇篮对振荡的图片。总体目标是确定是否可以将冲浪区视为二维湍流框。这项研究将通过解决四个特定的假设来提高对冲浪区涡流产生和进化的动力学的理解，从而导致瞬时撕裂电流和相关的跨架交换：1）短空波是一个重要的涡度来源，在短空间和时间尺度上，2）较小的涡流凝聚在较大的范围内，从而在较大的范围内进行了稳定的效率，3）稳定的Eddionce eddy ed Indiction ed Indife ed Indiction edy eD eD Inction fordife the Isdy fordife et difection edy edy eD eD fordife the Is eD fordife the Is dy Ised Is dection dection dection fordife在架子上偏离二维范式的区域。实验室实验将包括原位和远程（可见的立体声和红外线）测量海表面的测量和一系列波高，周期和方向扩散的速度。最先进的数值建模将用于指导实验室采样，分析一系列条件的动态，并评估摩擦耗散和三维循环特性的重要性。如果可以将冲浪区视为强制二维湍流箱，则可以建立具有适当强迫的简化模型，以促进对冲浪区在土地到海上运输中的作用的理解。

项目成果

Modeled Three‐Dimensional Currents and Eddies on an Alongshore‐Variable Barred Beach

模拟沿岸可变障碍海滩上的三维水流和涡流

• DOI: 10.1029/2020jc016899
• 发表时间: 2021
• 期刊: Journal of Geophysical Research: Oceans
• 作者: Baker, Christine M.;Moulton, Melissa;Raubenheimer, Britt;Elgar, Steve;Kumar, Nirnimesh
• 通讯作者: Kumar, Nirnimesh