Surfzone Energy Cascades

Surfzone 能量级联

基本信息

批准号：
1948137
负责人：
Steve Elgar
金额：
$ 97.84万
依托单位：
Woods Hole Oceanographic Institution
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-03-01 至 2025-02-28
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1948137&HistoricalAwards=false
关键词：
Surfzone Energy Cascades

项目摘要

Rotational currents with order 0.1 m/s velocities and periods of about 30 minutes have been observed in many surf zone environments and for a wide range of conditions. These low-frequency surf zone eddies provide a mechanism for cross-shore dispersion and exchange of material between the shore and the inner continental shelf. This study tests the hypothesis that low-frequency surf zone currents may be the result of energy transfer from breaking waves. Existing data from an extensive two-dimensional array of wave and current sensors will be analyzed to investigate the inverse energy cascade to lower frequencies. Due to limitations in the spatial scales resolvable by the existing data, new data will be collected through the deployment of an alongshore array of wave and current sensors in the surf zone. The sensor deployment will occur during a multi-agency-funded field project to take place in 2020, leveraging significant infrastructure and ancillary measurements. In addition to understanding the contribution of these low frequency oscillations to material exchange between the surf zone and the coastal ocean, the study will also address the need for exposure of future scientists and professional engineers in field data collection and analysis. The project will provide students and young coastal professionals field data collection experiences and 1-week long workshops in analyzing field observations. In addition, the research will form part of the dissertation of an MIT-WHOI PhD student advised by the PIs.There are several hypotheses for the generation of low-frequency surf zone motions, including instabilities of mean currents (shear waves), slow modulations of the incident wave field (wave groups), and nonlinear energy transfers (breaking waves). The wide range of observed wave conditions in existing field data sets, combined with new observations will allow separation and isolation of these mechanisms. Preliminary analyses of surf zone observations suggest that some statistics of the low-frequency current field are consistent with the expectations of a two-dimensional inverse energy cascade. Based on preliminary results, two hypotheses have been formulated and will be investigated as part of this project: (1) vortical energy with spatial scales of a few meters injected into the surf zone at the ends of high frequency (50 to 300 mHz) breaking wind waves is transferred to low-frequency ( 4 mHz) surf zone currents via a two-dimensional inverse cascade, and (2) enstrophy (the integral of vorticity squared) is transferred from breaking-wave-generated vorticity to smaller-scale, higher-frequency motions via a two-dimensional forward cascade. The spatial scale for which the inverse and forward cascades intersect is an indication of the spatial scale of the injected vorticity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在许多冲浪区环境和各种条件下都观察到了速度为 0.1 m/s 量级、持续时间约为 30 分钟的旋转流。这些低频冲浪区涡流提供了一种跨岸分散和海岸与内陆架之间物质交换的机制。这项研究检验了低频冲浪区电流可能是破碎波浪能量转移的结果的假设。将分析来自波和电流传感器的广泛二维阵列的现有数据，以研究较低频率的逆能量级联。由于现有数据可解析的空间尺度有限，将通过在冲浪区部署沿岸波浪和电流传感器阵列来收集新数据。传感器部署将在 2020 年进行的多机构资助的实地项目期间进行，利用重要的基础设施和辅助测量。除了了解这些低频振荡对冲浪区和沿海海洋之间物质交换的贡献外，该研究还将解决未来科学家和专业工程师接触现场数据收集和分析的需求。该项目将为学生和年轻的沿海专业人员提供实地数据收集经验和为期 1 周的分析实地观测的研讨会。此外，该研究将成为由 PI 指导的 MIT-WHOI 博士生论文的一部分。低频冲浪区运动的产生有多种假设，包括平均电流（剪切波）的不稳定性、慢调制入射波场（波群）和非线性能量传输（破碎波）。现有现场数据集中观测到的各种波浪条件与新的观测结果相结合，将允许分离和隔离这些机制。对海浪区观测的初步分析表明，低频流场的一些统计数据与二维逆能量级联的预期一致。根据初步结果，我们提出了两个假设，并将作为该项目的一部分进行研究：（1）在高频（50至300 mHz）断裂结束时将几米空间尺度的涡旋能量注入冲浪区风波通过二维逆级联转移到低频（4 mHz）冲浪区电流，并且（2）熵（涡度平方的积分）从碎波生成转移通过二维前向级联将涡度转化为更小规模、更高频率的运动。反向和正向级联相交的空间尺度指示了注入涡量的空间尺度。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Field Evidence of Inverse Energy Cascades in the Surfzone

冲浪区逆能量级联的现场证据

DOI：
10.1175/jpo-d-19-0327.1
发表时间：
2020-08
期刊：
Journal of Physical Oceanography
影响因子：
3.5
作者：
Elgar, Steve;Raubenheimer, Britt
通讯作者：
Raubenheimer, Britt

Observations of two-dimensional turbulence in the surfzone

表面区二维湍流的观测

DOI：
10.1063/5.0159170
发表时间：
2023-08
期刊：
Physics of Fluids
影响因子：
4.6
作者：
Elgar, Steve;Dooley, Ciara;Gorrell, Levi;Raubenheimer, Britt
通讯作者：
Raubenheimer, Britt

Field Observations of the Evolution of Plunging‐Wave Shapes

暴跌演变的现场观察——波浪形状

DOI：
10.1029/2021gl093664
发表时间：
2021-08
期刊：
Geophysical Research Letters
影响因子：
5.2
作者：
O'Dea, Annika;Brodie, Katherine;Elgar, Steve
通讯作者：
Elgar, Steve

Coastal topography and hydrogeology control critical groundwater gradients and potential beach surface instability during storm surges

沿海地形和水文地质控制风暴潮期间的关键地下水梯度和潜在的海滩表面不稳定

DOI：
10.5194/hess-26-5987-2022
发表时间：
2022-01
期刊：
Hydrology and Earth System Sciences
影响因子：
6.3
作者：
Paldor, Anner;Stark, Nina;Florence, Matthew;Raubenheimer, Britt;Elgar, Steve;Housego, Rachel;Frederiks, Ryan S.;Michael, Holly A.
通讯作者：
Michael, Holly A.

Coastal flooding generated by ocean wave- and surge-driven groundwater fluctuations on a sandy barrier island

海浪和浪涌驱动的沙障岛上地下水波动引起的沿海洪水