Collaborative Research: Interaction Between Plumes and Surface Waves from the Surf Zone to the Inner-Shelf

河流在输送陆源物质方面发挥着重要作用（例如，沉积物、污染物）和淡水流入沿海海洋，后者影响沿海环流。然而，近岸波浪和波浪破碎在羽流混合、输送和最终沿着海岸线的命运中的作用还不清楚。为了解决这一知识差距，该项目使用测量和数值模型相结合，以确定沿海海洋中漂浮的河流羽流水的命运。两个实地实验的观测结果将测量河流羽流在沿海海洋中的扩散和混合。结合理想化的数值模拟，这些现场的现实模拟将允许实验跨越广泛的参数空间，以相关的不同类型的河流跨越各种海岸线。这项工作将使人们更好地了解河水在沿海海洋中的混合和命运，这对于量化近岸沉积物、污染物、幼虫和其他重要物质的扩散至关重要。因此，这项工作将有助于确定与减轻不同条件下沿海水质差造成的风险有关的空间和时间尺度，改善沿海水质预测，减少人类接触受污染的沃茨。这项研究将提高动力学的理解小开尔文数，中小流量的河流羽流存在的深度有限的表面波。先前的研究表明，重要的波羽结构和混合的影响，但显着的知识差距仍然存在的理解波/羽的相互作用，在一系列的河流排放和整个冲浪区/内陆架区域。这些知识差距限制了我们预测小型河流及其携带的物质最终命运的能力，这些物质与沿海污染，幼虫运输等有关。初步模拟表明，有显着的波浪驱动的羽修改，包括增强沿岸扩展内冲浪区和减少淡水出口到内陆架。一套理想化的耦合海洋环流和波传播模型模拟不同的河流流量，波高，波的方向，潮汐阶段，和科里奥利强迫将提供一个参数空间，探索波/羽相互作用。理想化研究的结果将通过现有研究中心（现有观察结果和现实模型输出）和新的补充研究中心的结论进行扩充。新研究地点的观测活动和现实模拟旨在捕获在现有地点未捕获的缺失参数空间和羽流度量。最后，将对理想化和现实模型以及观测数据集进行综合分析，以解决四个关键假设。这项研究最终将：（1）确定将羽流水截留在碎波带内的物理机制，（2）描述河流与波浪动量通量对羽流范围的作用，（3）确定截留在碎波带内的淡水输出到内陆架的途径，（4）对现有的湍流闭合模型进行深度-该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Rivers play an important role in delivering land-derived material (e.g., sediment, contaminants) and freshwater to the coastal ocean, the latter impacting coastal circulation. Yet the role of near-shore waves and wave breaking in plume mixing, transport, and ultimate fate along the coastline is not yet understood. To address this knowledge gap, this project uses a combination of measurements and numerical models to determine the fate of buoyant river plume water in the coastal ocean. Observations from two field experiments will measure river plume spreading and mixing in the coastal ocean. Realistic simulations of these field sites combined with idealized numerical simulations will allow the experiment to span a broad range of parameter space in order to be relevant to different types of rivers across a variety of coastlines. The improved understanding of river water mixing and fate in the coastal ocean that will result from the work is crucial to quantifying the spreading of sediment, pollutants, larvae, and other important material in the nearshore. Thus, this work will aid in identifying the spatial and temporal scales relevant to mitigating risks due to poor coastal water quality under varying conditions, improving coastal water quality predictions and reducing human exposure to contaminated waters. This study will improve the dynamical understanding of small Kelvin number, small-moderate discharge river plumes in the presence of depth-limited surface waves. Prior research has shown important wave impacts on plume structure and mixing, yet significant knowledge gaps remain in the understanding of wave/plume interactions across a range of river discharge and across the surf zone/inner-shelf region. These knowledge gaps limit our ability to predict the ultimate fate of small rivers and the material they carry with them, relevant to coastal pollution, larval transport, and more. Preliminary simulations suggest there is significant wave-driven plume modification including enhanced along-shore spreading within the surf zone and decreased freshwater export to the inner-shelf. A suite of idealized coupled ocean circulation and wave propagation model simulations for varying river discharge, wave height, wave direction, tidal stage, and Coriolis forcing will provide a parameter space to explore wave/plume interaction. The results from idealized studies will be augmented with conclusions from an existing study site (with existing observations and realistic model output) and a new complementary study site. The observational campaign and realistic simulations of the new study site are designed to capture the missing parameter space and plume metrics that were not captured at the existing site. Finally, combined analyses of the suite of idealized and realistic models and observational datasets will be done to address four key hypotheses. Ultimately this study will: (1) Determine the physical mechanisms that trap plume water within the surf zone, (2) characterize the role of riverine versus wave momentum fluxes on plume extent, (3) identify pathways through which freshwater trapped in the surf zone gets exported to the inner shelf, and (4) test existing turbulence closure models in the region of depth-limited wave breaking in the presence of buoyancy gradients.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.