CAREER: Lagrangian investigation of upper ocean turbulence

上层海洋中的湍流过程通过耦合海洋和大气，在天气和气候系统中发挥着关键作用。上层海洋湍流还会在海洋混合层中分布营养物质、污染物、浮游生物和气泡。化学和生物物质在混合层中的去向取决于平流湍流路径的历史。除了分散，海洋湍流还会聚集物质，以增加它们之间的相遇几率。上层海洋湍流是由表面波驱动的：波与流的相互作用导致风向涡旋，称为朗缪尔环流(LC)，而破碎波是近地表湍动能的来源。LC和随机破碎波场共同导致了复杂的非局部和间歇性输运。为了更好地了解复杂海洋边界层的动力学，并教育学生了解上层海洋过程，国际海洋研究所将开展一项相互交织的研究和教育计划。本项目是一项系统的拉格朗日研究，其目标是：1)建立一个具有真实表面波效应的上层海洋拉格朗日分析框架，以研究表面波存在时流体交换的基本机制；2)研究LC和破碎波在上层海洋输送中的作用，以系统地评估共同的上层海洋边界层参数化的准确性；3)应用拉格朗日分析对作为主要海洋污染物的塑料海洋废弃物进行量化，并重新审视有关上层海洋中颗粒捕获的相关经典思想。粒子的轨迹将根据具有LC和破碎波效应的最先进的上层海洋大涡模拟模型来计算。作为拉格朗日分析的一部分，该项目将对波浪驱动的上层海洋边界层采用一种新的综合动力系统方法。为了直接利用从这项研究中获得的知识，国际海洋研究所将检查观察到的塑料海洋垃圾的分布情况。该项目涉及与上层海洋动力学研究活动相联系的两项相关教育活动，其教育目标是：1)对学生进行关于海洋物理学及其在气候变化和全球污染中的作用的教育；2)通过让学生参与以问题为基础的学习和实施下一代科学标准，激励学生从事STEM教育和职业；3)让代表性不足的学生参与。第一个教育活动将包括国际海洋协会参与海洋教育协会关于海洋废弃物的积极教育方案，接触到本科生和普通公众。第二项教育活动的中心是建立一个动手实验室教育单元，该单元将被纳入学生人数较少的高中的常规课程，也将被纳入特拉华大学促进少数族裔工程学方案的论坛，该方案旨在增加少数族裔学生对工程和其他科学专业的有效参与。这两项活动都融合了PI在地球物理流体动力学、上层海洋物理和正在进行的研究合作方面的专业知识。智力上的优点：通过揭示吸引、排斥和强烈混合的区域，拉格朗日框架提供了一种自然的方法来研究尚未在波浪驱动的上层海洋动力学背景下系统探索的湍流。因此，这项研究具有很高的潜力来揭示一种新颖的、高度物理的高层海洋湍流描述，最终将在更大尺度的海洋模式中增强湍流输送的参数化。更广泛的影响：PI将通过提高对海-气通量和海洋湍流的参数化能力来推进天气和气候的海洋-大气耦合模式。这项研究将促进海洋物理学和海洋废弃物研究界之间的交流，这是有效量化和最终管理海洋污染的必要步骤。由于海洋污染的主题对广大受众来说是可以接触到的，项目活动提供了一个独特的机会，在与上层海洋动力学、数值模拟、动力系统理论和出海海洋学专家合作的环境中，教育普通公众、高中生、少数族裔学生、本科生和研究生有关海洋湍流和流体动力学的知识。

Turbulent processes in the upper ocean play a key role in weather and climate systems by coupling the ocean and atmosphere. Upper ocean turbulence also distributes nutrients, pollutants, plankton, and bubbles in the ocean mixed layer. The fate of chemical and biological substances in the mixed layer depends on the history of advective turbulent fluid paths. Besides being dispersive, ocean turbulence also aggregates substances to increase encounter rates between them. Upper ocean turbulence is driven by surface waves: Wave-current interactions lead to wind-aligned vortices, called Langmuir circulation (LC), and breaking waves are a source of near surface turbulent kinetic energy. Together, LC and the stochastically breaking wave field lead to complicated nonlocal and intermittent transport. To better understand the dynamics of the complex oceanic boundary layer and to educate students about upper ocean processes, the PI will carry out an interwoven research and education program. This project is a systematic Lagrangian investigation following trajectories of fluid parcels with the Research Objectives to: 1) Develop a Lagrangian analysis framework of the upper ocean with realistic surface wave effects to investigate fundamental mechanisms of fluid exchange in the presence of surface waves, 2) Examine the role of LC and breaking waves in upper ocean transport to assess systematically the accuracy of common upper ocean boundary layer parameterizations, 3) Apply the Lagrangian analysis to quantify plastic marine debris that has emerged as a major ocean pollutant and to revisit related classic ideas of particle trapping in the upper ocean. Tracks of particles will be computed from state-of-the art upper ocean large eddy simulation models with LC and breaking wave effects. As part of the Lagrangian analysis, this project will apply a new and integrative dynamic systems approach to the wave-driven upper ocean boundary layer. To directly utilize knowledge gained from this study, the PI will examine observed distributions of plastic marine debris. The project involves two related education activities that are linked to the research activities on upper ocean dynamics with the Education Objectives to: 1) Educate students about ocean physics and its role in climate change and global pollution, 2) Inspire students to pursue STEM education and careers by engaging students in problem-based learning and implementing Next Generation Science Standards, 3) Involve underrepresented students. The first educational activity will involve the PI's participation in the active education programs on marine debris at the Sea Education Association, reaching out to undergraduate students and the general public. The second education activity is centered on developing a hands-on laboratory educational unit, which will be incorporated into regular curricula of high schools with a large number of underrepresented students and also into the University of Delaware's Forum to Advance Minorities in Engineering Program, which is aimed at increasing the effective participation of minority students in engineering and other science professions. Both activities incorporate the PI's expertise in geophysical fluids dynamics, upper ocean physics, and ongoing research collaborations.Intellectual Merit: By revealing regions of attraction, repulsion, and intense mixing, the Lagrangian framework provides a natural approach to investigating turbulence that has yet to be systematically explored in the context of wave-driven upper ocean dynamics. Thus, the study bears high potential to uncover a novel, highly physical description of upper ocean turbulence that will ultimately enhance the parameterizations of turbulent transport in larger scale ocean models.Broader Impacts: The PI will advance coupled ocean-atmosphere models of weather and climate by improving the ability to parameterize air-sea fluxes and ocean turbulence. The research will facilitate communication between the ocean physics and marine debris research communities, a necessary step in effectively quantifying and ultimately managing ocean pollution. Because the topic of marine pollution is accessible to a broad audience, the project activities present a unique opportunity to educate the general public, high school minority students, undergraduate students, and graduate students about ocean turbulence and fluid dynamics in a collaborative environment with experts in upper ocean dynamics, numerical modeling, dynamic systems theory, and sea-going oceanography.