Collaborative Research: Study of Convectively-Breaking Internal Solitary Waves of Depression: High Accuracy/Resolution Modeling and Observational Data Analysis

合作研究：抑郁症的对流破坏内孤立波研究：高精度/分辨率建模和观测数据分析

• 批准号: 1634182
• 负责人: Ren-Chieh Lien
• 金额: $ 22.97万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1634182&HistoricalAwards=false
• 关键词: Collaborative; Research; Study; Convectively; Breaking

Internal solitary waves (ISWs) are ubiquitous oceanic phenomena found on continental slopes and shelves, in submarine canyons, and over oceanic topographic features. They can carry energy over long distances while maintaining their shapes, are efficient suppliers of nutrients into the upper ocean, and can impact primary production and marine ecology through the exchange of heat, salt, nutrient, and water masses between the open ocean and coastal waters. For example, recent measurements of internal solitary waves shoaling on the continental shelf of New Jersey indicate that waves linked to shear instability in their interior are responsible for 50% of the total heat flux across the pycnocline and drive horizontal particle transport over a few kilometers, thereby exerting a critically important role for the shelf energetics and ecology. On account of the massive overturns in their interior, the turbulent diffusivities and particulate transport in convectively-breaking ISWs are expected to be as much as a hundred times larger than those in shear-unstable ISWs. Existing in-situ observations of convectively unstable ISWs are limited in their resolution of the associated turbulence due to the transient nature of these instabilities and instrument limitations. This project will enable the robust determination of the mechanisms and preferred locations of convective (and shear) instability of shoaling ISWs. The implications of convective breaking will be addressed through quantifying the associated turbulent fluxes and particle transport as a function of parameter space. A more reliable assessment of whether convectively-breaking ISWs are a critically important feature of most environments rich in high-amplitude waves will be possible. The improved understanding and quantification of the convective breaking process in shoaling ISWs, in terms of preferred locations of occurrence, underlying physics, turbulent fluxes and onshore particulate transport, will facilitate the reliable parameterization of such processes in larger-scale models. The parameterizations of ISW breaking and resulting turbulence, phenomena focused on the continental slope and shelf, might be fundamentally different from those typically used for internal tides, internal lee waves and stratified turbulence in the open ocean. One Ph.D. student, a native of Puerto Rico and member of a under-represented minority, will be trained in stratified ocean physics and high performance computing. The findings of this study will be integrated in relevant coursework in Environmental Fluid Mechanics at Cornell and in on-going outreach efforts at Ithaca High School and the Applied Physics Laboratory at the University of Washington's Space Grant Summer Undergraduate Research Program. Analysis codes, post-processed results and select raw data will be made available to the broader community through a dedicated online database.This project will investigate the breaking, due to primarily convective (but also shear) instability, of internal solitary waves (ISWs) shoaling over gently sloping realistic (and idealized) bathymetries. High-accuracy/resolution Large Eddy Simulations (LES) will be integrated with analysis of an extensive dataset of convectively breaking ISWs over the continental slope in the South China Sea. Previous analysis of these observations has revealed convectively unstable, large-amplitude ISWs with recirculating turbulent cores in their interior associated with order 100 meter overturns and intensified dissipation and mixing, roughly a thousand times greater than in the open ocean. The mechanisms leading to the convective instability and the associated turbulence mixing remain unknown. Two-dimensional simulations will first investigate the mechanisms and preferred locations of ISW breaking due to convective instability as a function of bottom slope, initial wave steepness and background baroclinic tidal current. Focusing on convective breaking, a range of computation/data intensive parallel three-dimensional LES, equipped with Lagrangian particle tracking, will then provide enhanced spatiotemporal resolution of the breaking process and will quantify the dependence of the resulting turbulent fluxes and wave-scale horizontal energy fluxes on the above parameters. Beyond providing bathymetric and stratification/current forcing to the LES, the existing SCS observations, and further analysis thereof, will serve as a basis for consistency checks and exploration of common trends in parameter space between LES and field data. Analysis of data from, actual and model, Lagrangian floats will examine and quantify particle entrainment, transport and detrainment by convectively-breaking ISWs, namely waves with recirculating cores. Alternative Lagrangian estimates of turbulent fluxes and dissipation rates will enable the computation of associated eddy diffusivities. These results will determine how ISW-driven turbulence relates to the regimes of weak wave-wave interaction and stratified turbulence and the transition between them.

内孤立波（ISW）是一种普遍存在于陆坡、陆架、海底峡谷和海洋地形上的海洋现象。它们可以长距离携带能量，同时保持其形状，是上层海洋营养物质的有效供应者，并可以通过公海和沿海沃茨之间的热、盐、营养物质和水体交换影响初级生产和海洋生态。例如，最近测量的内孤立波变浅的大陆架上的新泽西表明，在其内部的剪切不稳定性的波是负责的总热通量的50%的密度跃层和驱动器水平粒子传输超过几公里，从而发挥了至关重要的作用，为大陆架能量学和生态学。由于在其内部的大规模翻转，湍流扩散系数和颗粒输送对流打破ISW预计将高达100倍以上的剪切不稳定ISW。现有的对流不稳定ISW的原位观测是有限的，由于这些不稳定性和仪器的限制，在其相关的湍流的分辨率。该项目将使强大的确定机制和对流（和剪切）不稳定性的浅水ISW的首选位置。对流破裂的影响将通过量化相关的湍流通量和粒子输运作为参数空间的函数来解决。一个更可靠的评估是否对流打破ISW是一个至关重要的功能，大多数环境中丰富的高振幅波将是可能的。在发生的首选位置，基本的物理，湍流通量和陆上颗粒物运输方面，更好地理解和量化的对流破裂过程中变浅ISW，将有助于可靠的参数化，这些过程在大尺度模型。ISW破碎和由此产生的湍流的参数化，现象集中在大陆坡和大陆架，可能是从根本上不同于那些通常用于内潮，内背波和分层湍流在公海。一个博士学生是土生土长波多黎各人，属于代表性不足的少数民族，将接受分层海洋物理学和高性能计算方面的培训。这项研究的结果将纳入康奈尔大学环境流体力学的相关课程，并纳入伊萨卡高中和华盛顿大学应用物理实验室的空间赠款夏季本科生研究计划正在进行的外联工作。分析代码、后处理结果和选定的原始数据将通过一个专门的在线数据库提供给更广泛的社区，该项目将调查主要由于对流（但也有剪切）不稳定性而导致的内孤立波（ISW）在缓倾斜的现实（和理想化）水深测量上变浅的破裂。高精度/分辨率的大涡模拟（LES）将被集成到一个广泛的数据集的对流打破ISW在中国南海大陆坡的分析。先前对这些观测结果的分析揭示了对流不稳定的大振幅ISW，其内部具有再循环湍流核心，与100米量级的翻转和强化的耗散和混合有关，大约是公海的一千倍。导致对流不稳定和相关的湍流混合的机制仍然是未知的。二维模拟将首先调查的机制和首选位置的ISW打破由于对流不稳定作为底坡，初始波陡度和背景斜压潮流的函数。专注于对流破碎，一系列的计算/数据密集型并行三维LES，配备拉格朗日粒子跟踪，然后将提供增强的时空分辨率的破碎过程，并将量化的依赖所产生的湍流通量和波尺度水平能量通量的上述参数。除了提供测深和分层/电流强迫LES，现有的SCS观测，并进一步分析，将作为一致性检查和探索LES和现场数据之间的参数空间的共同趋势的基础。分析数据，实际和模型，拉格朗日浮子将检查和量化颗粒夹带，运输和对流破坏ISW，即波与再循环的核心。湍流通量和耗散率的替代拉格朗日估计将使相关的涡流扩散率的计算。这些结果将确定如何ISW驱动的湍流与弱波-波相互作用和分层湍流的制度，以及它们之间的过渡。

项目成果

Formation of Recirculating Cores in Convectively Breaking Internal Solitary Waves of Depression Shoaling over Gentle Slopes in the South China Sea

南海缓坡洼地浅滩对流破碎内孤立波中循环核心的形成

• DOI: 10.1175/jpo-d-19-0036.1
• 发表时间: 2020
• 期刊: Journal of Physical Oceanography
• 影响因子: 3.5
• 作者: Rivera-Rosario, Gustavo;Diamessis, Peter J.;Lien, Ren-Chieh;Lamb, Kevin G.;Thomsen, Greg N.
• 通讯作者: Thomsen, Greg N.