Diapycnal mixing induced by breaking internal waves over topography

许多值得注意的野外观测表明，不可逆混合主要是由水下地形特征与内波相互作用驱动的。该项目将模拟内波与地形的非线性相互作用，并将为量化破碎内波引起的谷底混合提供新的知识/概念。模型数据比较将用于测试混合参数化的充分性。从全球气候预测到内波驱动的内波混合在海洋生态系统营养物质运输中的关键作用，对内波驱动的内波混合的理解和参数化的改进将提供广泛的科学影响。通过该项目对研究生的培训/指导对教育产生了更广泛的影响。外联工作包括PI参与由科罗拉多州立大学（CSU）工程专业的妇女和少数民族协调的暑期校园/项目，以及通过组织访问PI在CSU新建的环境流体力学实验室向当地高中生进行外联。高分辨率直接数值模拟（DNS）和大涡模拟（LES）将使用欧拉和拉格朗日视角的组合来阐明小尺度混合过程/机制，并着眼于参数化由内波破裂引起的近边界混合的显著物理现象。该项目的主要目标是：(1)利用一系列高分辨率的内波-地形相互作用的微观结构研究，研究动量和标量（密度）混合的相关长度尺度和时间尺度之间的关系；(2)建立由内波与单一和多个地形特征相互作用驱动的底波混合参数化；(3)解释NLIWs在与地形相互作用过程中的命运，并确定它们是否对混合和运输有重要贡献。该奖项反映了美国国家科学基金会的法定使命，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。

Many noteworthy field observations indicate that diapycnal (irreversible) mixing is primarily driven by internal waves interacting with underwater topographic features. This project will model the nonlinear interactions of internal waves with topography, and will lead to new knowledge/concepts for quantifying diapycnal mixing induced by breaking internal waves. Model-data comparisons will be used to test the adequacy of mixing parameterizations. Improvements in understanding and parameterizations of diapycnal mixing from internal waves will provide a wide range of scientific broader impacts, from global climate prediction to the crucial role that internal wave driven diapycnal mixing plays in transport of nutrients for the oceanic ecosystem. Broader impacts on education stem from the training/mentoring of a graduate student through this project. Outreach efforts include the PI’s involvement in summer campus/programs coordinated by the Women and Minorities in Engineering at Colorado State University (CSU) as well as through outreach to local high school students through organized visits to the PI’s new Environmental Fluid Mechanics Laboratory at CSU.Highly resolved direct numerical simulations (DNS) and large-eddy simulations (LES) using a combination of Eulerian and Lagrangian perspectives will be employed to elucidate small-scale mixing processes/mechanisms with an eye towards parameterization of the salient physics for near boundary mixing resulting from the breaking of internal waves. The main objectives of the project are to: (1) investigate the relationships between relevant length scales and time scales for mixing of both momentum and scalar (density) using a series of high-resolution “numerical” microstructure profile studies of internal wave- topography interactions; (2) formulate parameterizations for diapycnal mixing driven by internal waves interacting with single and multiple topographic features; and (3) explain the fate of NLIWs as a result of the interaction process with topography and determine whether they contribute significantly to mixing and transport.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.