Connection Between Mass Flux Transport and Eddy Diffusivity in Convective Atmospheric Boundary Layers
Connection Between Mass Flux Transport and Eddy Diffusivity in Convective Atmospheric Boundary Layers
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DOI：
10.1029/2020gl092073
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发表时间：
2021-03
影响因子：
5.2
通讯作者：
Qi Li;Yu Cheng;P. Gentine
中科院分区：
文献类型：
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作者：
Qi Li;Yu Cheng;P. Gentine
粗尺度大气模式中对流边界层的湍流参数化通常考虑涡动扩散输运和非局部输运的组合，通常以质量通量项的形式，例如广泛采用的涡动扩散质量通量（EDMF）方法。这两种类型的湍流输送通常被认为是相互独立的。使用大涡模拟的结果，在这里，我们表明，上升气流和下降气流质量通量输送的泰勒级数展开可用于近似大气表层和混合层下部的涡扩散率输送，连接对流条件下的涡扩散率和质量通量输送理论，这也量化了表层中与莫宁-奥布霍夫相似性（MOS）的偏离。该研究为统一的EDMF参数化方案提供了理论支持，并强调了依赖MOS的地面模式所需的重要修正。
Turbulence parameterizations for convective boundary layer in coarse‐scale atmospheric models usually consider a combination of the eddy‐diffusive transport and a non‐local transport, typically in the form of a mass flux term, such as the widely adopted eddy‐diffusivity mass‐flux (EDMF) approach. These two types of turbulent transport are generally considered to be independent of each other. Using results from large‐eddy simulations, here, we show that a Taylor series expansion of the updraft and downdraft mass‐flux transport can be used to approximate the eddy‐diffusivity transport in the atmospheric surface layer and the lower part of the mixed layer, connecting both eddy‐diffusivity and mass‐flux transport theories in convective conditions, which also quantifies departure from the Monin‐Obukhov similarity (MOS) in the surface layer. This study provides a theoretical support for a unified EDMF parameterization applied to both the surface layer and mixed layer and highlights important correction required for surface models relying on MOS.