Acta Scientiarum Naturalium Universitatis Pekinensis

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Large-Eddy Simulations of Atmospheric Boundary Layers from Convective to Near-Neutral Conditions

CAI Xuhui, CHEN Jiayi   

  1. Department of Environmental Sciences, College of Environmental Sciences, Peking University, Beijing, 100871
  • Received:2002-07-16 Online:2003-07-20 Published:2003-07-20

从不稳定到近中性大气边界层的大涡模拟

蔡旭晖,陈家宜   

  1. 北京大学环境学院环境科学系,北京,100871

Abstract: Large-eddy simulations are carried out for atmospheric boundary layers from con vective to near-neutral cases. The simulation condition covers the range as follows: surface heat flux from 0.0001 to 0.2 K·m·s-1, geostrophical wind speed from 0~15 m·s-1, and the correspondent stability parameter -z/L from 0.0062 to 368. Simulation results show that in the atmospheric boundary layer, the heat flux and momentum flux profiles have the form as those in typical unstable condition and near neutral condition. And within the stability situation the model resolves the turbulence in ABL well, in good agreement with observation data, particularly in surface layer. By current resolution, the model does not properly simulate turbulent characters in near neutral boundary layer. While convective roll vortices may emerge in strong wind and weak unstable condition, with the stability range of -z/L from 0.668 to 24.6 approximately.

Key words: atmospheric boundary layer, large-eddy simulation, unstable, near-neutral, roll vortices

摘要: 用大涡模拟方法对不稳定到近中性层结的大气边界层情况进行模拟。模拟条件为:地面运动学热通量0.0001~0.2 K·m·s-1、地转驱动风速0~15 m·s-1,对应的无因次稳定度参数 - z/L 为0.0062~368。模拟结果显示,大气边界层直到 - z/L=0.668的近中性情况,其热通量和动量通量等仍保留着典型对流边界层的基本特征,可由模式较好地求解,且在近地面与观测结果相符较好。对更接近中性的情况,模式分辨率限制了对边界层湍流特性的求解。在大风、弱不稳定边界层条件下模拟发现有滚动涡现象出现,其稳定度范围大致对应- z/L 的取值0.668~24.6。

关键词: 大气边界层, 大涡模拟, 不稳定, 近中性, 滚动涡

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