Collaborative Research: Role of Eddies in the Midlatitude Ocean Circulation

中尺度涡旋输送动量、热量和盐是大尺度海洋环流的重要组成部分。一般的环流模式通常不能直接解决涡旋问题，而必须依赖湍流闭包参数化。常见参数化的一个特别弱点是它们不允许梯度上通量，在那里涡流通量会进入大尺度梯度，而不是侵蚀它们。本研究将探索一种新的方法，通过表示随机力方面的非解析涡流效应来规避这一限制。首先，将分析越来越复杂和现实的海洋模型层次的解决方案。本文将采用一种新的海洋湍流动力学分解方法，将其分解为涡旋分量和大尺度分量。系统地分析了大尺度涡旋相互作用，即涡旋通量的组成及其发散。其次，将系统地评估旋涡力随机模型的性能，并与几种现有的参数化方案进行比较。拟议工作的更广泛影响是，它将有助于一般环流和气候系统的建模、观测数据集的解释以及旨在估计关键涡旋通量的未来观测策略的规划。此外，所追求的想法可能会对其他湍流领域产生影响，其中亚网格尺度过程建模是一个重要问题。

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.