Small-Scale Processes in the COASTal Ocean

俄勒冈州立大学海洋混合小组作为海岸海洋大陆架运输进展项目的一部分所做的观察已经使人们对海岸流动的细节有了新的认识。这些是在广泛的地形和流动状态范围内获得的广泛的观察结果。这些数据具有一致的高质量，包括专门为本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规模动力学的能力。然而，由于该数据集的广泛性，仍然需要解决一些关键问题。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COAST数据集的分析，以确定可用于沿海海洋环流模式的小规模地形阻力和混合的有用参数化；这将使用综合的底部边界层数据，包括近底部分层、湍流耗散率和大水深范围内的当前速度。将详细描述下井过程中的混合，包括对合并的表面和底部边界层的动力学分析。研究人员还将评估近惯性波和内部潮汐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切变的混合参数化。最后，对底阱非线性内波/高程孔的能量演化和这些波的净质量输运进行了量化。这项工作的主要目标是了解流动物理，以充分帮助参数化，然后可以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。研究生也将接受训练，学习如何在小尺度动力学和大尺度变量的参数化之间架起桥梁。

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.