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能直接解决涡旋问题，而必须依赖于湍流闭合参数。常规参数化的一个特别缺点是它们不允许向上梯度通量，在这种情况下涡通量输送到大尺度梯度中，而不是侵蚀它们。这项研究将探索一种新的方法，通过用随机力来表示未分辨的涡流效应来绕过这一限制。首先，将分析日益复杂和逼真的海洋模型的层次结构的解。在这里，将应用一种新的海洋湍流的动力学分解为涡旋和大尺度分量。将系统地分析大尺度/涡旋相互作用，即涡通量的分量及其散度。其次，对涡动力随机模型的性能进行了系统的评估，并与现有的几种参数化方案进行了比较。拟议工作的更广泛影响是，它将有助于建立大气环流和气候系统模型，有助于解释观测数据集，并有助于规划旨在估计关键涡旋通量的未来观测战略。此外，所追求的想法可能会对湍流的其他领域产生影响，在这些领域，对次网格尺度的过程进行建模是一个重要的问题。

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.