Collaborative Research: Quantifying Stratified Turbulence in Estuaries

理解强层结中的湍流混合是流体力学中一个长期存在的基本问题。这项研究的目的是确定河口在大梯度Richardson数下混合的机制，并测试在该区域内的湍流参数。这一体系中的大多数高质量数据都来自实验室测量和直接的数值模拟。湍流通量和耗散率的现场测量对于理解地球物理相关尺度上的湍流是必不可少的。河口是分层湍流的极佳实验室，因为它们将强烈的层化和强烈的潮汐强迫结合在一起。测量、模拟和分析将阐明分层湍流和河口动力。测量是在两个河口进行的，预计混合是由截然不同的机制驱动的。流动湍流传感阵列(MAST)测量将得到三维雷诺平均数值模拟的补充，这将把测量与更大尺度的河口动力学联系起来，并允许评估湍流参数。MASTER是一种新型的野外仪器平台，能够以前所未有的时空分辨率解析关键湍流量。这些目标将通过在固定和在航模式下具有高空间和时间分辨率的湍流通量、耗散率和长度尺度的主尺度测量来检查，从而允许长时间序列测量和空间变异性的量化。三维数值模型在河口和沿海环境中作为管理工具发挥着越来越重要的作用。更广泛的影响还将包括一个明确的组成部分，以传达这项研究的影响，以改进河口和沿海环流模式中用于跨学科科学和管理应用的湍流闭合参数。

Understanding turbulent mixing in strong stratification is a longstanding fundamental problem in fluid dynamics. The objectives of the proposed study are to determine the mechanisms responsible for estuarine mixing at large gradient Richardson number and to test turbulence parameterizations in this regime. Most high-quality data in this regime have resulted from laboratory measurements and direct numerical simulations. Field measurements of turbulent fluxes and dissipation rates are essential to understand turbulence at geophysically relevant scales. Estuaries are excellent laboratories for stratified turbulence because they combine strong stratification with strong tidal forcing. The measurements, simulations, and analyses will elucidate both stratified turbulence and estuarine dynamics. Measurements are conducted in two estuaries where the mixing is expected to be driven by distinctly different mechanisms. The Mobile Array for Sensing Turbulence (MAST) measurements will be complemented by three-dimensional Reynolds-averaged numerical simulations, which will place the measurements in context with the larger scale estuarine dynamics and permit evaluations of the turbulence parameterizations. The MAST is a new field instrument platform that can resolve key turbulent quantities with unprecedented spatial and temporal resolution. The objectives will be examined with MAST measurements of turbulent fluxes, dissipation rates, and length scales with high spatial and temporal resolution in fixed and underway modes, thus permitting both long time-series measurements and quantification of spatial variability. Three-dimensional numerical models play an increasingly important role as management tools in estuarine and coastal environments. The broader also impacts will include an explicit component to communicate the implications of this study to improve the turbulence-closure parameterizations in estuarine and coastal circulation models for interdisciplinary science and management applications.