A simple formulation for the eddy‐diffusivity parameterization of cloud‐topped boundary layers
A simple formulation for the eddy‐diffusivity parameterization of cloud‐topped boundary layers
复制标题
云顶边界层涡流扩散率参数化的简单公式
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
J. Teixeira
中科院分区：
文献类型：
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作者：
S. Cheinet;J. Teixeira
提出了一种新的多云边界层涡扩散系数参数化公式。该方案的新方面是：（i）两个预报湍流动能（TKE），为晴朗和多云的空气;（ii）在每个区域中，混合长度制定的TKE和时间尺度。此外，还使用了统计云方案。该模型在解耦层积云的情况下，并在积云的情况下，使用单柱模式进行评估。该模型逼真地模拟了总体云属性。云内混合长度公式定性地匹配典型的涡流大小（如从大涡流模拟中诊断的）。子云和云层之间的一致相互作用通过逼真的云内混合来实现。在积云的情况下，条件不稳定层保持。这些结果表明，边界层云和相关的混合可以在涡流扩散率方法的背景下一致地表示。
A new formulation for the eddy‐diffusivity parameterization of the cloudy boundary layer is presented. The new aspects of the scheme are: (i) two prognostic turbulent kinetic energies (TKE), for the clear and cloudy air; (ii) in each region, the mixing length is formulated in terms of the TKE and a time scale. Additionally a statistical cloud scheme is used. The model is evaluated in a decoupling stratocumulus case and in a cumulus case, using a single‐column mode. The model realistically simulates the overall cloud properties. The in‐cloud mixing length formulation qualitatively matches the typical eddy size (as diagnosed from large eddy simulations). Consistent interactions between the sub‐cloud and the cloud layers are achieved through a realistic in‐cloud mixing. In the cumulus case, the conditionally unstable layer is maintained. These results show that boundary layer clouds and associated mixing can be represented consistently in the context of the eddy‐diffusivity approach.