CAREER: A new perspective on the transformation of internal waves on the inner shelf

在像海洋这样的分层流体中，波可以发生在不同密度的水层之间的界面上。这些被称为内波，它们在深海盆地和中到外大陆架区域进行了大量研究。然而，陡峭的内波在大陆架内很常见，可以改变湍流混合、大陆架上的物质交换和沿海沃茨的生物生产力。这项研究将进行密集的现场活动和数值模拟，旨在解决内部波的转换，包括打破和耗散的货架。从历史上看，内波是使用在固定位置使用系泊或垂直温度剖面进行的次表层海洋温度观测来检测的，每种观测都有自己的分辨率限制。这项研究使用了光纤分布式温度传感系统，这是一种新的方法，可以在大陆架上的大面积（公里）上进行测量，具有高的空间分辨率（1米）和时间分辨率。这些测量将与水文和湍流变量的更传统的点测量相结合。这项工作的结果将深入了解底栖生态学、营养物质和污染物的跨大陆架交换、湍流混合、幼虫连接、沿海缺氧和海洋酸化。这个CAREER项目的教育部分是基于这样一个想法，即帮助学生在科学领域取得成功并塑造下一代创新者的最佳方法之一是激发对科学的热情。这是通过研究和教学的整合和活动，使课程概念与激发学生的社会问题，并通过展示毅力是成功的重要组成部分。在大学一级，将重新设计课程，以包括：㈠与正在进行的研究有关的社会科学问题，㈡鼓励冒险和坚持不懈的积极学习技巧，作为科学发现的建设性途径。在小学和中学教育层面，研究人员将开发一个导师工具包，以帮助那些希望成为榜样但缺乏基础教育培训的STEM职业专业人士，最有效地传达他们的科学之路以及他们一路上面临和克服的斗争。非线性内波（NLIWs）的“冲击区”及其不稳定性和小的时空尺度对观测提出了挑战。因此，有几个全面的现场测量的NLIWs内架测试动力学理论来自众多的实验室和数值研究。该项目将使用高分辨率的湍流测量，再加上一个密集的水文仪器和湍流测量阵列，以捕捉一个连续的跨大陆架演变的NLIWs。在南中国海进行的一项试点研究的结果表明，波浪测量可以为NLIW提供一个独特的视角-允许检测内波特征（形式和路径），可变传播速度，反射，波浪相互作用和“内部潮池”（波浪沿着斜坡返回后留下的冷水）。此外，相对于船为基础的测量，它必须物理上遵循一个波在货架上，建议的测量能够捕捉到一个跨货架的许多波的视图，并将有助于了解在货架上的内部波的变化“天气”。观测将在两个位置进行，代表不同的大陆架几何形状和特征内波场，并将对数据进行分析，以提高我们对大陆架内部NLIW变换，内波能量命运，以及NLIWs对质量通量和湍流混合的影响。该奖项反映了NSF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。

In a layered fluid like the ocean, waves can occur in the interface between the different density layers of water. These are called internal waves and they have been largely studied in deep ocean basins and mid-to-outer continental shelf regions. However, steep internal waves are common in the inner shelf and can modify turbulent mixing, exchange of materials across the continental shelf, and biological productivity of coastal waters. This research will conduct an intensive field campaign and numerical modeling aiming at resolving the transformation of internal waves across the shelf including breaking and dissipation. Historically, internal waves are detected using observations of subsurface ocean temperature that are made at fixed locations using moorings or vertical profiles of temperature, each with their own limitations in resolution. This research uses a fiber optic distributed temperature sensing (DTS) system, a new method that provides measurement over large areas over the shelf (kilometers), with high spatial (1 meter) and temporal resolutions. These measurements will be combined with more traditional point measurements for hydrographic and turbulence variables. Results from this work will yield insights into benthic ecology, cross-shelf exchange of nutrients and pollutants, turbulent mixing, larval connectivity, coastal hypoxia, and ocean acidification. The educational component of this CAREER project is based on the idea that one of the best ways to help students succeed in the sciences, and to shape the innovators of the next generation is to inspire passion for science. This is achieved through the integration of research and teaching and activities that relate curricular concepts to societal issues that excite the students, and by demonstrating how perseverance is an important part for success. At the university level, courses will be re-designed to include: (i) socio-scientific issues related to ongoing research, and (ii) active learning techniques that encourage risk-taking and perseverance as a constructive path to scientific discovery. At primary and secondary education levels, the investigator will develop a mentor-toolkit to help professionals in STEM careers, who desire to serve as a role model but lack training in elementary education, to most effectively communicate their path to science and the struggles that they faced and overcame along the way.The inner shelf is, in effect, a "swash zone" for nonlinear internal waves (NLIWs) and their intermittency and small spatiotemporal scales pose challenges to observation. Consequently, there are few comprehensive field measurements of NLIWs on the inner shelf to test dynamical theories derived from numerous laboratory and numerical studies. This project will use high resolution DTS measurements, coupled with a dense array of hydrographic instruments and turbulence measurements, to capture a continuous view of the cross-shelf evolution of NLIWs. Results from a pilot study in the South China Sea demonstrate that DTS measurements can provide a unique perspective on NLIWs - allowing for detection of internal wave characteristics (form and path), variable propagation speed, reflection, wave-wave interactions, and "internal tidepools" (cool water left behind after the wave has run back down the slope). Furthermore, as opposed to boat-based measurements, which must physically follow a wave across the shelf, the proposed measurements are capable of capturing a cross-shelf view of many waves and will be useful for understanding variability in internal wave "weather" on the shelf. The observations will be performed at two locations, representing different shelf geometries and characteristic internal wave fields, and the data will be analyzed to advance our knowledge on NLIW transformation over the inner shelf, the fate of internal wave energy, and the effects of NLIWs on mass flux and turbulent mixing.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.