Collaborative Research: Rapid Gravitational Adjustment of Horizontal Shear: A Recipe for Energetic Mixing in the Coastal Ocean

合作研究：水平切变的快速重力调整：沿海海洋高能混合的秘诀

• 批准号: 0726475
• 负责人: Alberto Scotti
• 金额: $ 9.96万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0726475&HistoricalAwards=false
• 关键词: Collaborative; Research; Rapid; Gravitational; Adjustment

Intellectual Merit The study will extend our knowledge of mixing processes in the coastal ocean through a comprehensive examination of the stability and evolution of horizontally sheared flows in the presence of a horizontal density contrast. This configuration of shear and stratification is common in strongly time-dependent flows in the coastal ocean including estuarine inflows and outflows, separating flows around headlands and islands, and merging flows in morphologically complex regions such as tidal inlets. The resulting buoyancy-driven flow results in tilting and intense stretching of the shear-flow vortices and ultimately a breakdown of the flow leading to intense vertical mixing. Horizontal stratification in the presence of horizontal shear has the potential to strongly enhance mixing, despite the fact that the gravity-driven flow by itself increases the vertical stratification. The research into the dynamics and consequences of this process will involve both high-resolution non-hydrostatic numerical modeling and comprehensive laboratory experiments utilizing particle image velocimetry and laser-induced fluorescence. Scaling arguments for this highly nonlinear evolution have been developed and will guide the investigation. It is expected that the results will inform future parameterizations of mixing processes that are crucial in coastal ocean circulation models. Broader Impacts Coastal mixing processes are important for pollutant transport and dilution, biogeochemical cycles of nutrients and carbon in the productive coastal zone, and the transport of marine larvae and plankton. The results of this study will yield understanding that should lead to improved parameterizations for mixing that can be incorporated into estuarine water quality, coastal ocean circulation, and ecological models. The PIs are both active in their respective academic programs (MIT/WHOI Joint Program and UNC Marine Science) and the results of this research will quickly reach the classroom. The grant will also provide important early career support for undergraduate and graduate students will be incorporated into aspects of the research through the WHOI Summer Student Fellowship Program and the Geophysical Fluid Dynamics (GFD) Summer Program at WHOI. The grant will support the continued operation of the WHOI GFD Laboratory, which has hosted over 100 visiting students and scientists over the last 30 years to undertake a variety of experiments spanning physical oceanography, atmospheric dynamics, fluid dynamics, and geological processes.

这项研究将通过全面考察在存在水平密度对比的情况下水平切变流动的稳定性和演变，扩展我们对沿海海洋混合过程的知识。这种切变和分层结构在沿海海洋中非常依赖于时间的流动中很常见，包括河口的流入和流出，围绕海角和岛屿的分离流动，以及在形态复杂的区域(如潮汐入海口)的合并流动。由此产生的浮力驱动的流动导致剪切流涡的倾斜和强烈拉伸，最终导致流动的破裂，导致强烈的垂直混合。存在水平切变的水平层结具有强烈增强混合的潜力，尽管重力驱动的流动本身增加了垂直层结。对这一过程的动力学和后果的研究将涉及高分辨率非静力数值模拟和利用粒子图像测速和激光诱导荧光的综合实验室实验。这种高度非线性演化的标度论点已经发展出来，并将指导这项研究。预计这些结果将为未来混合过程的参数化提供信息，这些混合过程在沿海海洋环流模式中至关重要。更广泛的影响沿海混合过程对于污染物的转移和稀释、多产沿海地区营养物质和碳的生物地球化学循环以及海洋幼体和浮游生物的转移都很重要。这项研究的结果将产生理解，这将导致改进的混合参数，可纳入河口水质、沿海海洋环流和生态模型。这两个专业人员都积极参与各自的学术项目(麻省理工学院/世界卫生组织联合项目和北卡罗来纳大学海洋科学)，这项研究的结果将很快进入课堂。这笔赠款还将为本科生和研究生提供重要的早期职业支持，这些学生将通过世界卫生组织暑期学生奖学金计划和世界卫生组织地球物理流体动力学(GFD)暑期计划被纳入研究的各个方面。这笔赠款将支持WHOI GFD实验室的继续运营，该实验室在过去30年中接待了100多名来访的学生和科学家，开展了涵盖物理海洋学、大气动力学、流体动力学和地质过程的各种实验。