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

在许多沿海地区，已观测到大振幅、高频内波和内潮孔向岸上传播。由于它们的振幅很大，这些浅滩波将能量从产生区域带到海岸，并在内外大陆架之间输送质量和浮力。实地观察表明，这些波浪可能对将幼虫阶段的底栖生物从大陆架运送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。海浪还可能对污水排放口的营养物和污染物的跨海岸运输和扩散作出重大贡献。在沿海海洋的一些地区，特别是在风和上升流较弱的地区，由于非线性内波引起的动量和浮力的跨岸输送可能是内大陆架动量和浮力收支的主要项。虽然现场证据表明，非线性内波对内大陆架的重要性是令人信服的，但缺乏对这些波的动力学及其相关通量的详细研究，而且尚未量化。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滩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年和1997年夏季和秋季在加利福尼亚州Mission Beach附近收集的实地观测资料外，首席研究员还将利用二维、旋转、非线性、非流体静力模型进行调查。数值模型将使用与现场观测相同的跨岸几何形状域运行，并将在近海系泊点观测到的内波场内进行强制。为了评估非线性内波的生态重要性，浮游生物通过内波活动的跨岸运输将被量化，并与其他运输机制（如上升流松弛或海岸困波）进行比较。此外，非线性浅化、破碎内波和内陆架密度场之间的反馈也将被量化，以确定它们与内陆架动量和浮力预算的机制相关性。更广泛的影响：从这个项目中收集的结果不仅可以更好地了解沿海幼虫和营养物质的命运，还可以阐明人口稠密地区雨水径流中污染物的命运。由于该项目适用于污水排放口的设计，该研究的结论报告将提交给圣地亚哥市都市污水处理部门，该部门在Pt. Loma附近运营一个污水排放口设施，就在这些实地观察的南部。

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.