Dynamic subgrid models are increasingly being used in simulations of the atmospheric boundary layer. We have implemented several variant forms of dynamic models in the UK Met Office Large Eddy Model (MetLEM), including a state-of-the-art Lagrangian-Averaged-Scale-Dependent (LASD) model. The implementation includes optional use of stability functions in the specification of the eddy viscosity and diffusivity, as well as optional use within the dynamic calculation of the Smagorinsky parameter. This paper reports on the behaviour of the LASD model with different choices for the inclusion and treatment of stability functions in convective boundary layer simulations at different resolutions. Results are compared against a high-resolution Large-Eddy simulation (LES) and against simulations employing the Smagorinsky-Lilly subgrid model. We conclude that the use of stability functions improves the behaviour of the LASD model in the grey zone regime. Moreover, a careful treatment of the stability functions in the calculation of the dynamic parameters, whilst attractive theoretically, is found to be unnecessary in practical terms.

中文翻译：

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动态模型对流边界层模拟中稳定性函数的影响

动态子网格模型越来越多地用于大气边界层的模拟。我们在英国气象局大涡模型 (MetLEM) 中实施了多种变体形式的动态模型，包括最先进的拉格朗日平均尺度相关 (LASD) 模型。该实现包括在涡粘度和扩散率规范中可选使用稳定性函数，以及在 Smagorinsky 参数的动态计算中可选使用。本文报告了 LASD 模型在不同分辨率下对流边界层模拟中包含和处理稳定性函数的不同选择的行为。结果与高分辨率大涡模拟 (LES) 和采用 Smagorinsky-Lilly 子网格模型的模拟进行了比较。我们得出结论，稳定性函数的使用改善了 LASD 模型在灰色区域制度中的行为。此外，在计算动态参数时仔细处理稳定性函数虽然在理论上很有吸引力，但在实践中被发现是不必要的。