Small-Scale Processes in the COASTal Ocean

俄勒冈州立大学海洋混合小组作为COSTARE(大陆架运输中的沿海海洋进展)项目的一部分所作的观测已经使人们对沿海流动的细节有了新的见解。这些是在地形和流动状态的广泛范围内获得的一组广泛的观测。这些数据具有一致的高质量，并包括专门为该实验实施的新型测量(例如，高频多普勒速度剖面和来自底部着陆器的湍流测量)，这些测量增强了我们推断这些流动的小尺度动力学的能力。然而，由于这一数据集的广泛性质，仍有许多关键问题需要解决。在这项研究中，俄勒冈州立大学的一名研究人员将继续他对小规模海岸数据集的分析，以确定可用于沿海海洋环流模式的小尺度地形阻力和混合的有用参数；这将使用包括近底部层结、湍流消散率和大范围水深测量中的水流速度的综合底层边界层数据来完成。将对下沉过程中的混合进行详细的描述，包括对合并的表面和底部边界层的动力学进行分析。研究人员还将评估近惯性波和内潮与海岸急流的相互作用，以及海岸急流的存在如何改变主要基于波浪切变的混合参数。最后，将量化底陷非线性内波/高程钻孔的能量演化和这些波的净质量传输。这项工作的主要目标是了解流动物理，以充分帮助参数化，然后将其应用于沿海海洋模型。这样，对小尺度过程的物理分析将有助于我们对大尺度环流的理解。一名研究生还将接受关于如何弥合小尺度动力学与它们在大尺度变量方面的参数化之间的差距的培训。

Observations made as part of the COAST (Coastal Ocean Advances in Shelf Transport) project by the Ocean Mixing Group at Oregon State University have already led to new insights into the details of coastal flows. These are an extensive set of observations obtained over a broad range of both topography and flow states. The data are of uniformly high quality and include new types of measurements implemented specifically for this experiment (e.g., high-frequency Doppler velocity profiling and turbulence measurements from a bottom lander) which have enhanced our ability to infer the small-scale dynamics of these flows. However, due to the extensive nature of this data set a number of key issues still need to be addressed.In this study, a researcher at Oregon State University will continue his analysis of the small-scale COAST data set to determine a useful parameterization of small-scale topographic drag and mixing that can be used in coastal ocean circulation models; this will be done using the comprehensive bottom boundary layer data that includes near-bottom stratification, turbulence dissipation rate and current speeds over a broad range of bathymetry. A detailed characterization of mixing during downwelling, including an analysis of the dynamics of merged surface and bottom boundary layers will be constructed. The researcher will also assess the interaction of near-inertial waves and internal tide with the coastal jet and how the presence of the coastal jet alters mixing parameterizations that are based primarily on wave shear. Finally, both the energetic evolution of bottom-trapped nonlinear internal waves/bores of elevation and the net mass transports by these waves will be quantified. The primary objective of the work is to understand the flow physics to sufficiently aid in parameterizations, which can then be applied to coastal ocean models. In this way, the analyses of the physics of small-scale processes will contribute to our understanding of the larger scale circulation. A graduate student will also be trained on how to bridge the gap between small-scale dynamics and their parameterization in terms of larger-scale variables.