Abstract In the present work the possibility of turbulence closure applying to improve barotropic jet instability simulation at coarse grid resolutions is considered. This problem is analogous to situations occurring in eddy-permitting ocean models when Rossby radius of deformation is partly resolved on a computational grid. We show that the instability is slowed down at coarse resolutions. As follows from the spectral analysis of linearized equations, the slowdown is caused by the small-scale normal modes damping arising due to numerical approximation errors and nonzero eddy viscosity. In order to accelerate instability growth, stochastic and deterministic kinetic energy backscatter (KEBs) parameterizations and scale-similarity model were applied. Their utilization led to increase of the growth rates of normal modes and thus improve characteristic time and spatial structure of the instability.

中文翻译：

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正压射流不稳定模拟的二维湍流闭合

摘要 在目前的工作中，考虑了湍流闭合应用于改进粗网格分辨率下的正压射流不稳定性模拟的可能性。这个问题类似于在计算网格上部分解决罗斯比变形半径时允许涡流的海洋模型中发生的情况。我们表明，在粗分辨率下，不稳定性会减慢。根据线性化方程的谱分析，减速是由数值近似误差和非零涡粘性引起的小尺度正常模式阻尼引起的。为了加速不稳定性增长，应用了随机和确定性动能反向散射 (KEB) 参数化和尺度相似性模型。