CAREER: Shoaling of Non-Linear Internal Waves over Gentle Slopes: Wave-Scale Interactions and Dissipative Processes

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)资助的。非线性内波(NLIW)是沿海海洋和湖泊的普遍特征，位于自然分层水体中由风和潮汐引发的大规模能量级联的接收端。这些海浪将这些能量输送到100公里以外的缓坡(浅海)陆架地区，并将其远距离地消散。最近在南中国海和新泽西大陆架进行的大规模野外实验为了解西北低地线浅滩的过程提供了宝贵的见解。然而，由于现场测量在空间和时间上的局限性，关于波浪浅化的一些关键问题仍然没有得到解答，即相关的能量耗散机制，这些机制因可变水深引起的大范围波浪变换而进一步复杂化。为此，迫切需要小规模的数值模拟。该项目旨在利用一个完全非静力和非线性的平行谱四边形子域惩罚方法模型来数值研究缓坡上的非静力和非线性的非线性浅滩现象。该模式使波浪内部/足迹中的小尺度耗散过程与波浪尺度的最大可能尺度分离，并使后者具有最佳的分辨率，从而使雷诺数尽可能接近海洋数值。模拟将集中于浅化引起的波尺度变化的基本物理及其对NLIW诱导的海底边界层和次表层捕获的再循环核心的三维湍流耗散动力学的影响。与上述地点的现场数据(包括一组非常丰富的记录在案的南中国海面上的近海和被困岩芯的观测数据)的近距离比较将为模拟建立一致性检查，从测量中充实基本物理，并为未来的部署提供指导。在关闭海洋和湖泊的大规模能源收支方面，了解北冰洋和湖泊足迹和内部的湍流耗散物理学是一个关键的缺失环节。此外，圈闭岩芯内的流场和NLIW诱导的海底边界层分别可以驱动生物群/营养物质的水平迁移和底陷生物地球化学组分的强烈再悬浮。除了对波浪浅化的基本物理进行更深入的描述外，该项目还将为未来研究近海水域内的流场如何直接与水下生态、声学和光学相互作用并影响水质奠定基础。改进的颗粒物再悬浮和近海底/表层耗散的参数化方案将被开发用于更大尺度的模式和现场数据分析。与南中国海场数据的密切比较将启动康奈尔大学和华盛顿大学之间积极的长期合作。所有重要的数值结果将通过互联网数据库传播给感兴趣的海洋学社区成员。在嵌入多领域求解器的先进数值方法的推动下，一个紧密相连的教育活动链寻求在研究生/本科生水平上启动对当前科学计算教育范式的重新考虑，并促进高中生进入理工科专业。从研究生课程开始，拟议的教育计划旨在培养海洋模型用户，他们虽然不是开发人员，但拥有与尖端计算方法保持一致的强大的数值和海洋学专业知识。科学计算二年级课程的重组将使本科生能够发现这一研究领域的潜力，并将其作为完成科学和工程研究的工具，从而建立未来数值建模人员进入研究生队伍的持续流动。一个为期一周的关于湖泊内波模拟的高中课程模块将向不同的高中生介绍计算建模，作为传统“湿实验室”的替代方案，以及未来科学和工程应用计算研究的选择。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Nonlinear internal waves (NLIWs), ubiquitous features of the coastal ocean and lakes, are on the receiving end of an energy cascade initiated at large scales by the winds and tides in stratified natural water bodies. These waves transport this energy over 100km distances across gently sloping (shoaling) shelf regions and dissipate it remotely. Recent massive field-scale experiments in the South China Sea and the New Jersey Shelf have provided invaluable insight into the process of NLIW shoaling. Nonetheless, due to limitations of field measurements in space and time, a number of key questions on wave shoaling remain unanswered, namely in terms of the associated energy dissipation mechanisms, which are further complicated by the large-scale wave transformations due to variable bathymetry. To this end, small-scale numerical modeling is imperatively needed.The project aims at the use of a fully non-hydrostatic and nonlinear parallel spectral quadrilateral sub-domain penalty method model to numerically study shoaling of NLIWs over gentle slopes. The model enables the maximum possible scale separation between wave-scale and the small-scale dissipative processes in the wave interior/footprint with optimal resolution of the latter, allowing a Reynolds number as close as possible to the oceanic value. Simulations will focus on the basic physics of wave-scale transformations due to shoaling and their impact on the three-dimensional turbulent dissipative dynamics of the NLIW-induced benthic boundary layer and subsurface trapped recirculation cores. A close comparison with field data from the above sites (including a very richly documented set of observations from the South China Sea on NLIWs and trapped cores) will establish consistency checks for the simulations, flesh out the basic physics from the measurements and provide guidance for future deployments. Understanding the physics of turbulent dissipation in the NLIW footprint and interior is a crucial missing link in the closure of large-scale energy budgets in the ocean and lakes. Furthermore, the flow fields inside trapped cores and the NLIW-induced benthic boundary layer can drive powerful horizontal biota/nutrient transport and intense resuspension of bottom-lodged biogeochemical constituents, respectively. Beyond an enhanced description of the fundamental physics of wave shoaling, the project will offer the foundation for future investigations on how the flow fields within NLIWs directly interact with underwater ecology, acoustics and optics and impact water quality. Improved parameterizations of particulate re-suspension and near-bottom/surface dissipation may then be developed for use in larger-scale models and field data analysis.The close comparison with South China Sea field data will initiate an active long-term collaboration between Cornell and the University of Washington. All important numerical results will be disseminated to interested members of the oceanographic community via an internet database.Motivated by the advanced numerical methods embedded in the multi-domain solver, a tightly linked chain of educational activities seeks to initiate a reconsideration of the current paradigm in scientific computing education at the graduate/undergraduate level and to boost recruitment of high school students into science and engineering majors. Starting with graduate coursework, the proposed educational plan aims to create ocean model users who, although not developers, have a robust numerical and oceanographic expertise which is aligned with cutting edge computational methods. The restructuring of a sophomore-level course on scientific computing will allow undergraduate students to discover the potential of this research area and embrace it as a vehicle to complete their studies in the sciences and engineering, thereby establishing a consistent flux of future numerical modelers to the graduate ranks. A one-week high-school course module on internal wave simulation in lakes will introduce a diverse audience of high school students to computational modeling as an alternative to the traditional 'wet lab' and the option of future studies in applied computation in science and engineering.