Collaborative research: Coastal inertial-band dynamics: separating forced and free responses in a natural laboratory

合作研究：沿海惯性带动力学：在自然实验室中分离受迫响应和自由响应

• 批准号: 1635166
• 负责人: Jonathan Nash
• 金额: $ 12.09万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-15 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1635166&HistoricalAwards=false
• 关键词: Collaborative; research; Coastal; inertial; band

Surface winds globally impart about half a terawatt of energy to inertial oscillations in the surface mixed layer. The coastal ocean receives less wind work than the open ocean because it has less surface area. However, near-inertial wave generation is enhanced along coastlines, because the boundary induces large convergences and divergences in mixed-layer velocities. This process is dynamically significant because it transfers energy from forced surface-trapped motions to free motions, which can produce currents and turbulence in the stratified interior. Idealized theories and observations of the coastal ocean have confirmed the generation and propagation of near-inertial waves, but observational studies have not yet separated free and forced motions so that internal-wave generation, energy flux, and dissipation can be accurately quantified. Furthermore, the results of individual studies have not been synthesized to estimate the global significance or geography of coastal near-inertial wave generation. This project will improve the dynamical understanding and prediction of near inertial motions throughout the coastal ocean, in marginal seas, and in large lakes. The fieldwork will also contribute to our knowledge of the geophysical dynamics of Lake Superior, a valuable resource that is under-sampled with respect to physical measurements. These contributions include the first broad-scale turbulence measurements in the lake and the extension of a multi-year time series of density and currents. Coinciding measurements of chlorophyll fluorescence, turbidity, and oxygen will also illuminate the presently unknown relationships between turbulence and biogeochemistry in Lake Superior. The project will also develop tools and lessons for graduate oceanography and limnology courses, and support citizen science in Duluth, MN, via the development of a public drifter-building program in conjunction with the local office of the Environmental Protection Agency. The project will also train a PhD student and two undergraduate summer researchers.This project aims to quantify coastal kinetic-energy pathways from wind work to dissipation, and produce a detailed description of coastal inertial-band dynamics by extending existing theories of coastal near-inertial wave generation and definitively testing them. This will be done using realistic numerical simulations and intensive direct observations of wind work, mixed-layer and stratified turbulence, and near-inertial internal-wave generation, propagation, and dissipation along a coastline and over rough coastal topography. Specifically, extensive observations will collected in Lake Superior, which is dominated by near-inertial motions during summer and has negligible tides, weak mean circulation, and little river input, making it also an ideal laboratory of the coastal ocean. The observations will include broad-scale measurements of turbulence from ship-based surveys and Wirewalker wave-powered moored profilers. Three traditional moorings will also be deployed for four years, extending an existing time series that can be used to identify extreme events and long-term trends in near-inertial motions. The project also includes novel analyses of analytical and numerical models, which will aid in the collection and interpretation of observations and enable the results in Lake Superior to be extended throughout the coastal ocean using historical wind, stratification, and bathymetry data.

全球表面风在表面混合层中的惯性振荡中大约将能量的一半能量赋予。沿海海洋收到的风能少于公海，因为它的表面积较小。然而，沿海岸线近乎惯性波的产生增强，因为边界在混合层速度中引起了较大的收敛和差异。该过程具有动态意义，因为它将能量从强制表面捕获的运动转移到自由运动，这些运动可以在分层的内部产生电流和湍流。理想化的理论和沿海海洋的观察证实了近惯性波的产生和传播，但是观察性研究尚未分离自由和强迫运动，因此可以准确地量化内部波的产生，能量通量和耗散。此外，尚未合成个别研究的结果来估计沿海近惯性波产生的全球意义或地理。该项目将改善整个沿海海洋，边际海洋和大湖区的近乎惯性运动的动态理解和预测。现场工作还将有助于我们对苏必利尔湖的地球物理动力学的了解，苏必利尔湖的地球物理动力学是一种有价值的资源，在物理测量方面被采样不足。这些贡献包括湖泊中的第一个大规模湍流测量以及延长了多年的密度和电流。叶绿素荧光，浊度和氧气的重合测量还将阐明苏必利尔湖目前未知的湍流与生物地球化学之间未知的关系。该项目还将通过与环境保护署当地办公室共同开发公共漂流者建设计划，以开发明尼苏达州德卢斯市的公民科学的工具和课程。该项目还将培训一名博士生和两名本科夏季研究人员。该项目旨在量化从风能到耗散的沿海动力学能源途径，并通过扩展沿海惯性的近乎惯性的近族临时波产生理论来详细描述沿海惯性波动，并确定测试它们。这将使用现实的数值模拟以及对风能，混合层和分层的湍流以及沿海岸线和崎rough的沿海地形上的近乎惯性的内波产生，繁殖和耗散的直接直接观察。具体而言，将在苏必利尔湖（Lake Lake Lake）收集广泛的观察结果，苏必利尔湖（Lake Lake Lake）由夏季的近乎惯性动作主导，潮汐却可以忽略不计，平均循环较弱和少量河流投入，也使其成为沿海海洋的理想实验室。这些观察结果将包括对基于船舶的调查和WireWalker波动式系泊剖面的湍流的广泛测量。还将部署三个传统的系泊设备四年，扩大现有的时间序列，该时间序列可用于识别极端事件和近年运动的长期趋势。该项目还包括对分析和数值模型的新分析，这些分析将有助于收集和解释观察结果，并通过历史风，分层和测深数据来延伸整个沿海海洋的苏装湖的结果。