Interpolation of LES Cloud Surfaces for Use in Direct Calculations of Entrainment and Detrainment
Interpolation of LES Cloud Surfaces for Use in Direct Calculations of Entrainment and Detrainment
复制标题
用于直接计算夹带和脱轨的 LES 云表面插值
DOI：
10.1175/2010mwr3473.1
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发表时间：
2011
影响因子：
3.2
通讯作者：
P. Austin
中科院分区：
文献类型：
--
作者：
J. T. Dawe;P. Austin
摘要直接计算空气卷吸和卷吸进入云和云外的过程需要知道空气和云表面之间的相对速度差。然而，离散数值模式网格迫使云表面在时间步长上移动的距离为零或模型网格单元的宽度。本文提出了一种在离散数值模式网格上进行云面次网格插值的方法。用该方法计算了大涡模拟（LES）模型的卷吸和分离率，并与Romps直接通量法计算的卷吸和分离率进行了比较。比较表明，只要模型云很好地解决了模型网格间距，这两种方法之间的良好协议。这种技术的局限性是抵消的能力，以解决通量更精细的时间和空间尺度，使其适合于计算个别云的夹带和detrainment配置文件。
Abstract Direct calculations of the entrainment and detrainment of air into and out of clouds require knowledge of the relative velocity difference between the air and the cloud surface. However, a discrete numerical model grid forces the distance moved by a cloud surface over a time step to be either zero or the width of a model grid cell. Here a method for the subgrid interpolation of a cloud surface on a discrete numerical model grid is presented. This method is used to calculate entrainment and detrainment rates for a large-eddy simulation (LES) model, which are compared with rates calculated via the direct flux method of Romps. The comparison shows good agreement between the two methods as long as the model clouds are well resolved by the model grid spacing. This limitation of this technique is offset by the ability to resolve fluxes on much finer temporal and spatial scales, making it suitable for calculating entrainment and detrainment profiles for individual clouds.