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: 0927724
• 负责人: Chester Grosch
• 金额: $ 55.5万
• 依托单位: Old Dominion University Research Foundation
• 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 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0927724&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.

学术价值：Langmuir超级单体（LSC），即在浅海强风/波浪作用下吞没整个水柱的Langmuir环流，于2003年在新泽西州LEO15电缆观测站的垂直波束声学多普勒电流剖面仪测量中首次被发现。最近，在乔治亚海岸大陆架中部的海军R2塔上，在不同的风、浪和潮汐强迫条件下，也进行了类似的测量。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。建议通过对LEO15和R2数据集的分析，以及在观测指导下对LSC进行大涡模拟，研究LSC与潮汐强迫底边界层、破波和分层（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率范围内的观测结果进行比较得到验证，多过程LES将允许探索该范围之外的非量纲强迫参数，从而可以评估LC对大陆架的影响，而不是那些已有测量的大陆架。模拟将跨越参数空间进行。在遍历参数空间时，会遇到langmuir主导型湍流、对流主导型湍流和剪切主导型湍流等不同的湍流状态。状态图将有助于建立LSC占主导地位的大块强迫条件。对这些相互作用的理解将有助于加深对这些不同类型湍流动力学的理解，并改进湍流参数化，以便纳入考虑Langmuir湍流的大尺度沿海环流模式。改进后的参数化方法有望改善对浅陆架上垂直混合的预测，最终改善对跨陆架流动的预测。更广泛的影响：该项目将改善浅水湍流参数化，该参数化考虑了波浪-流相互作用，在许多广泛使用的环流模型中实现，可用于一般海洋学社区。拟议的开发主要集中在沿海海域，在那里海底的影响很重要。许多大陆架具有很高的生物生产力，例如美国主要渔场之一的白令海大陆架。这项研究将增加对控制生物活性物质和沉积物垂直混合和跨大陆架运输机制的理解。所开发的参数化和包含重要的物理学应该提高不同分辨率水平下沿海海洋流动模型的准确性，最终证明对耦合的物理-化学-生物模型很重要。本项目将资助一名博士后，在流体动力学、物理海洋学、数值方法和实验方法等多学科领域进行培训。Tejada-Martínez博士是该研究的共同作者之一，他是一名来自被忽视的少数群体的科学家。在拓展方面，萨维奇博士每年通过Skidaway？通过萨凡纳阿姆斯特朗大西洋州立大学为职前教师举办的研究座谈会。除了在Skidaway岛和Jekyll岛的海洋教育中心和水族馆进行自下而上的计算机交互式演示外，还将为公众提供视觉展示，并与萨维奇计划在那里安装的高频雷达相结合。该建模项目的重要结果将被纳入这些正在开发的显示器中。虽然建模的细节可能很难向非科学家表达，但有可能说明在主要风强迫事件期间模型性能的改进，并强调这些模型在预测近岸沿海海洋的幼虫和沉积物运输方面的重要性，这是公众最感兴趣的。