Nonlinear Internal Waves on the Inner Continental Shelf: Their Dynamics and Associated Cross-Shelf Fluxes

在许多沿海地区，观测到了大幅度、高频率的内波和内潮孔在岸上传播。由于它们的振幅很大，这些浅水波将能量从其产生区带到海岸，并在外大陆架和内大陆架之间传输质量和浮力。现场观察表明，这些波浪可能对将幼虫阶段的底栖生物从大陆架运回近岸地区至关重要，在那里它们可以在适当的栖息地定居。海浪还可能极大地促进来自排污口的营养物质和污染物的跨岸输送和扩散。在沿海海洋的一些区域，特别是在风和上升流较弱的区域，由于非线性内波引起的动量和浮力的跨岸输送可能是内陆架动量和浮力预算中的一个主要术语。虽然现场证据表明，内陆架上的非线性内波的重要性是引人注目的，但缺乏对这些波的动力学及其相关通量的详细调查，而且还有待于量化。在这个项目中，伍兹霍尔海洋研究所的一名研究人员将研究浅水和非线性内波的跨岸动量平衡，并量化与这些波相关的质量通量、浮力和拉格朗日输运。除了1996年夏季和1997年秋季在加利福尼亚州使命海滩附近收集的实地观测外，首席调查员还将利用一个二维、旋转、非线性、非静力模型进行调查。数值模式将使用与现场观测具有相同跨岸几何形状的区域运行，并将在近海系泊地点观测到的内部波场内强迫。为了评估非线性内波的生态重要性，将对通过内波活动的浮游生物的跨岸传输进行量化，并将其与其他传输机制(例如，上升流松弛或海岸捕获波)进行比较。此外，还将量化非线性浅化、破裂内波和内陆架密度场之间的反馈，以确定它们与内陆架动量和浮力收支的机械相关性。更广泛的影响：该项目收集的结果不仅将更好地了解沿海幼虫和营养物质的命运，而且还将澄清人口稠密地区雨水径流中污染物的命运。由于该项目适用于排污口的设计，这项研究的结论报告将提交给圣地亚哥市大都会污水处理部门，该部门在铂附近经营一个污水排放设施。洛马，就在这些现场观测的南边。

ABSTRACTOCE-0424742In many coastal regions large amplitude, high-frequency internal waves and internal tidal bores have been observed to propagate onshore. Because of their large amplitude, these shoaling waves carry energy from their generation regions towards the coast, and transport mass and buoyancy between the outer and inner continental shelf. Field observations suggest that these waves may be critical for transporting larval stage benthic organisms from the continental shelf back to nearshore regions, where they can settle at appropriate habitats. The waves may also significantly contribute to the cross-shore transport and dispersion of nutrients and pollutants from sewage outfalls. In some regions of the coastal ocean, particularly where winds and upwelling are weak, the cross-shore transport of momentum and buoyancy due to nonlinear internal waves may be a dominant term in the inner shelf momentum and buoyancy budgets. While field evidence suggests that the importance of nonlinear internal waves on the inner shelf are compelling, detailed investigations of the dynamics of these waves and their associated fluxes are lacking and have yet to be quantified. In this project, a researcher from the Woods Hole Oceanographic Institution will examine the cross-shore momentum balance of shoaling and nonlinear internal waves, as well as quantify the fluxes of mass, buoyancy, and the Lagrangian transports associated with these waves. In addition to the field observations that were collected in the summer and fall of 1996 and 1997 off of Mission Beach, California, the Principle Investigator will utilize a two-dimensional, rotating, nonlinear, non-hydrostatic model for his investigation. The numerical model will be run using a domain with the same cross-shore geometry as that of the field observations and will be forced within the internal wave field observed at the offshore mooring site. To assess the ecological importance of nonlinear internal waves, the cross-shore transport of plankton through internal wave activity will be quantified and compared to other transport mechanisms (e.g, upwelling relaxation or coastal trapped waves). In addition, the feedback between nonlinear shoaling, breaking internal waves, and the inner shelf density field will also be quantified to determine their mechanistic relevancy to the inner shelf momentum and buoyancy budgets. Broader Impacts: The results gathered from this project will not only yield a better understanding of the fate of larvae and nutrients along the coast, but also clarify the fate of pollutants from rain runoff in populated areas. Because of this project's applicability to the design of sewage outfalls, a report of the conclusions from this study will be presented to the City of San Diego Metropolitan Wastewater Department, who operates a sewage outfall facility off of Pt. Loma, just south of where these field observations were made.