Surfzone Vorticity

破碎的波浪在传递动量的同时消耗能量，该动量迫使水沿着波浪传播的方向运动。在浅水区的碎波带的时间平均波驱动的强迫提高水位附近的海岸线，并在斜入射波的情况下，驱动沿岸电流。由此产生的环流模式包括丰富的涡流和涡旋场。冲浪区漩涡已被假设为产生剪切沿岸流的不稳定性，由波群调制的海面，由破碎波的末端，并与复杂的水深相互作用的电流。该项目将解决这些假设与一套独特的高空间分辨率的估计电流从遥感和现场传感器在以前的实地研究，包括广泛的波条件和bathymetrys.Existing广泛的现场观测冲浪带波，环流模式，和底层的水深将被用来测试的假设冲浪带涡是从数值研究中得出的。这些假设包括：（1）在沿岸变化的海底，岸滩涡度的主要空间尺度取决于下垫面水深的空间尺度，这些大尺度涡度与海底的不均匀性有关：（2）小尺度涡度还取决于破碎波末端注入水柱的涡度，它随波场的方向性扩展而增大;（3）在高能条件下，沿岸流的动量可以克服造成复杂环流模式的力（如水深测量引起的压力梯度），导致沿岸均匀流，大尺度涡度显著降低。虽然这里使用的数据是从一个特定的现场，在十年内观察到的波和水深条件的广泛范围内允许开发一个冲浪区涡度气候学，将适用于许多location.This奖项反映了NSF的法定使命，并已被认为是值得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的支持。

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.