Surfzone Vorticity

面带涡度

• 批准号: 2341381
• 负责人: Steve Elgar
• 金额: $ 73.89万
• 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: 2024
• 资助国家: 美国
• 起止时间: 2024-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2341381&HistoricalAwards=false
• 关键词: Surfzone; Vorticity

Breaking waves dissipate energy while transferring momentum that forces water in the direction of wave propagation. In the shallow water of the surf zone the time-averaged wave-driven forcing raises water levels near the shoreline and, in the case of obliquely incident waves, drives alongshore currents. The resulting circulation patterns include a rich field of eddies and vortices. Surfzone eddies have been hypothesized to be generated by instabilities of sheared alongshore currents, by wave-group modulations of the sea surface, by the ends of breaking waves, and by currents interacting with complex bathymetry. This project will address these hypotheses with a unique suite of high spatial resolution estimates of currents from remote sensing and in situ sensors obtained during prior field studies that include a wide range of wave conditions and bathymetries.Existing extensive field observations of surfzone waves, circulation patterns, and underlying bathymetry will be used to test hypotheses about surfzone vorticity that were derived from numerical studies. These hypotheses include: (1) on an alongshore variable seafloor, the dominant spatial scales of surfzone vorticity depend on spatial scales of the underlying bathymetry, and these large-scale eddies are tied to the seafloor inhomogeneities; (2) small spatial-scale vorticity also depends on the vorticity injected into the water column at the ends of breaking waves, which increases with the directional spread of the wave field; (3) during energetic conditions, the momentum of alongshore currents can overcome forces (such as bathymetry-induced pressure gradients) that cause complex circulation patterns, resulting in alongshore-uniform flow with significantly reduced large-scale vorticity. Although the data used here are from a specific field site, the wide range of wave and bathymetric conditions observed over a decade allows development of a surfzone vorticity climatology that will be applicable at many locations.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.

打破波会散发能量，同时转移动量，从而迫使水向波传播的方向迫使水。在冲浪带的浅水中，随时间平均的波浪驱动强迫提高了海岸线附近的水位，并且在倾斜的入射波中，沿岸沿岸沿岸。所得的循环模式包括丰富的涡流和涡流场。已经假设表面涡流是由沿岸电流剪切的不稳定性，海面的波团调制，通过断裂波的末端以及与复杂的测深的电流相互作用而产生的。 This project will address these hypotheses with a unique suite of high spatial resolution estimates of currents from remote sensing and in situ sensors obtained during prior field studies that include a wide range of wave conditions and bathymetries.Existing extensive field observations of surfzone waves, circulation patterns, and underlying bathymetry will be used to test hypotheses about surfzone vorticity that were derived from numerical studies.这些假设包括：（1）在沿岸可变的海底，涡旋涡度的主要空间尺度取决于基础测深的空间尺度，这些大规模的涡流与海底的无处不在。 （2）小空间尺度涡度也取决于在断裂波的末端注入水柱中的涡度，这随波场的方向扩散而增加； （3）在高能条件下，沿岸电流的动量可以克服引起复杂循环模式的力（例如测深诱导的压力梯度），从而导致沿岸均匀的流动，并显着降低了大规模的涡度。尽管此处使用的数据来自特定的现场站点，但在十年中观察到的各种波浪和测深条件允许开发表面涡度气候，这些气候将适用于许多位置。该奖项反映了NSF的法定任务，并通过评估该基金会的智力优点和广泛的影响来评估NSF的法定任务。