Collaborative Research: Role of Eddies in the Midlatitude Ocean Circulation

中尺度涡旋对动量、热量和盐分的输送是大尺度海洋环流的重要组成部分。 大气环流模式通常不直接求解涡旋，而是依赖于湍流闭合参数化。常见参数化的一个特别的弱点是，它们不允许向上梯度通量，其中涡流通量进入大尺度梯度，而不是侵蚀它们。本研究将探讨一种新的方法来规避这一限制，代表非解决的涡流效应的随机力。首先，将分析日益复杂和现实的海洋模型层次结构的解决方案。在这里，一个新的动态分解的海洋湍流的涡流和大规模的组件将被应用。大尺度/涡的相互作用，即涡通量的组成部分和它们的分歧，将被系统地分析。其次，随机模型的涡流力的性能将系统地评估和比较对几个现有的参数化方案。拟议工作的更广泛的影响是，它将有助于大气环流和气候系统建模，在观测数据集的解释，并在规划未来的观测战略，旨在估计关键的涡流通量。此外，所追求的想法可能会对湍流的其他领域产生影响，其中模拟亚网格尺度过程是一个重要问题。

ABSTRACTOCE-0346178The transport of momentum, heat and salt by mesoscale eddies is an important component of the large-scale ocean circulation. General circulation models often do not resolve eddies directly but have to rely on turbulence closure parameterizations. One particular weakness of common parameterizations is that they do not allow up-gradient fluxes, where eddy fluxes feed into the large-scale gradients rather than erode them. This study will explore a novel approach to circumvent this limitation by representing the non-resolved eddy effects in terms of random forces. First, solutions of a hierarchy of ocean models of increasing complexity and realism will be analyzed. Here, a new dynamical decomposition of the oceanic turbulence into the eddy- and large-scale components will be applied. The large-scale/eddy interactions, that is, components of the eddy fluxes and their divergences, will be systematically analyzed. Second, the performance of the random model of the eddy forces will be systematically evaluated and compared against several existing parameterization schemes. The broader impacts of the proposed work is that it will aid in the general circulation and climate system modeling, in the interpretation of observational data sets, and in the planning of future observational strategies aimed at estimating the key eddy fluxes. Also, the ideas pursued are likely to have an impact on other areas of turbulence, where modeling subgrid-scale processes is an important issue.