Collaborative Research: LES & Modeling of Turbulence on Shallow Shelves under Combined Langmuir, Tidal & Convective Forcing with Comparison to VADCP Observations

合作研究：LES

• 批准号: 0926852
• 负责人: Dana Savidge
• 金额: $ 20.75万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0926852&HistoricalAwards=false
• 关键词: Collaborative; Research; LES; & Modeling

Intellectual Merit: Langmuir supercells (LSC), Langmuir circulations that engulf the entire water column during strong wind/wave forcing of shallow seas, were first identified in 2003 from vertical-beam acoustic Doppler current profiler measurements at the LEO15 cabled observatory off New Jersey. Similar measurements have been made more recently at the Navy's R2 tower on mid-shelf off the coast of Georgia, under different wind, wave and tidal forcing conditions. These unique data sets provide an opportunity, when combined with large-eddy simulations (LES) to investigate the interaction of several turbulence generating mechanisms in shallow seas. It is proposed to study the interaction between LSC, the tidally-forced bottom boundary layer, wave breaking and stratification (stable and unstable) from analysis of the LEO15 and R2 data sets and large-eddy simulation of LSC carefully guided by the observations. Once validated by comparison with the observations over the range of forcing ratios that characterize these data sets, the multi-process LES will allow exploration of non-dimensional forcing parameters outside this range, allowing assessment of the effect of LC on shelves other than those for which measurements exist. Simulations will be performed spanning parameter space. In traversing the parameter space, different turbulent regimes will be encountered such as Langmuir-dominated turbulence, convection-dominated turbulence and shear-dominated turbulence. Regime diagrams will help establish bulk forcing conditions for which LSC is dominant. Understanding of the interactions will lead to increased understanding of the dynamics of these various kinds of turbulence and to improved turbulence parameterizations for inclusion in large-scale coastal circulation models accounting for Langmuir turbulence. The modified parameterizations are expected to lead to improved predictions of vertical mixing on shallow shelves, ultimately leading to improved prediction of cross-shelf flows.Broader impacts: This project will result in improved shallow-water turbulence parameterizations accounting for wave-current interaction implemented within a number of widely used circulation models available to the general oceanography community. The proposed developments are focused in the coastal ocean where the effect of the bottom is important. Many continental shelves are biologically highly productive, for example the Bering Sea Shelf, one of the major United States fisheries. This research will increase understanding of the mechanisms controlling vertical mixing and cross shelf transport of biologically active materials and sediment. The parameterizations developed and the inclusion of important physics should improve the accuracy of models of coastal ocean flows at different resolution levels, ultimately proving important for coupled physical-chemical-biological models. This project will provide funding for a post-doctoral fellow who will train in multidisciplinary fields spanning fluid dynamics, physical oceanography, numerical methods and experimental methods. Dr. Tejada-Martínez, one of the co-PIs, is a scientist in an under-represented minority group. For outreach, Dr. Savidge participates yearly in training sessions for high school teachers through Skidaway?s local connections, and through research colloquia for pre-service teachers at Armstrong Atlantic State University in Savannah. Visual displays will be provided for the general public, adding to a computer-based interactive presentation BOTTOMS-UP in the Marine Education Center and Aquarium on Skidaway Island and on Jekyll Island, in conjunction with Savidge?s planned HF-radar installation there. Important results from this modeling project will be incorporated in these developing displays. While details of modeling may be difficult to express to non-scientists, it will be possible to illustrate improvements in model performance during major wind-forcing events, and to emphasize the importance of such models in predicting larval and sediment transport in the nearshore coastal ocean that is of most interest to the general public.

智能优点：朗缪尔超级单体(LSC)，即在浅海大风/浪强迫期间吞没整个水柱的朗缪尔环流，于2003年在新泽西州附近的LEO15有线天文台通过垂直波束声学多普勒海流剖面仪测量首次发现。最近，在佐治亚州海岸外陆架中部的海军R2塔也进行了类似的测量，在不同的风、浪和潮汐强迫条件下进行了测量。这些独特的数据集提供了一个机会，当与大涡模拟(LES)相结合时，可以研究浅海几种湍流产生机制的相互作用。通过对LEO15和R2资料的分析和观测指导下的LSC大涡模拟，提出了研究LSC与潮汐强迫底层边界层、波浪破碎和层结(稳定和不稳定)之间的相互作用。一旦通过与这些数据集特征的强迫比范围内的观测进行比较来验证，多过程LES将允许探索该范围之外的无维强迫参数，从而能够评估LC对陆架的影响，而不是那些存在测量的大陆架。模拟将在参数空间内进行。在穿越参数空间时，会遇到朗缪尔主导的湍流、对流主导的湍流和切变主导的湍流。状态图将有助于建立LSC占主导地位的整体强迫条件。对相互作用的了解将有助于加深对这些不同类型湍流的动力学的理解，并改进湍流参数，以便纳入考虑朗缪尔湍流的大型沿海环流模式中。修改后的参数方案有望改进对浅水陆架垂直混合的预测，最终导致改进对跨陆架流动的预测。广泛影响：该项目将导致改进的浅水湍流参数方案，考虑到在一些广泛使用的环流模型中实施的波流相互作用，这些环流模型可供一般海洋学使用。拟议的开发集中在沿海海洋，那里的海底影响很重要。许多大陆架的生物产量很高，例如美国的主要渔业之一白令海大陆架。这项研究将增进对生物活性物质和沉积物的垂直混合和跨陆架运输的控制机制的理解。所开发的参数和重要物理的纳入应提高不同分辨率水平的沿海洋流模型的准确性，最终证明对物理-化学-生物耦合模型是重要的。该项目将为一名博士后提供资金，该博士后将接受横跨流体动力学、物理海洋学、数值方法和实验方法的多学科领域的培训。Tejada-Martínez博士是联合PIs之一，他是一个代表人数较少的少数群体的科学家。为了扩大影响，萨维奇博士每年都会通过斯基德韦？S当地的关系网，以及萨凡纳的阿姆斯特朗大西洋州立大学职前教师研究座谈会，参加针对高中教师的培训课程。在斯基德韦岛和杰基尔岛的海洋教育中心和水族馆，以及救世主S计划在那里安装高频雷达的情况下，将为普通公众提供视觉展示，并增加基于计算机的自下而上的互动演示。这个建模项目的重要成果将被纳入这些正在开发的展示中。虽然模拟的细节可能很难向非科学家表达，但将有可能说明在主要强迫风事件期间模型性能的改进，并强调这种模型在预测公众最感兴趣的近岸沿海海洋的幼体和沉积物运输方面的重要性。