Resolution‐dependent behavior of subgrid‐scale vertical transport in the Zhang‐McFarlane convection parameterization
Resolution‐dependent behavior of subgrid‐scale vertical transport in the Zhang‐McFarlane convection parameterization
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张-麦克法兰对流参数化中亚网格尺度垂直传输的分辨率相关行为
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
H. Wan
中科院分区：
文献类型：
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作者：
H. Xiao;W. Gustafson;S. Hagos;Chien‐Ming Wu;H. Wan
为了更好地理解准平衡对流参数化在更高分辨率下的行为，我们使用诊断框架来检查由Zhang-McFarlane对流参数化（ZM）参数化的湿静能的亚网格尺度垂直传输的分辨率依赖性。ZM的网格尺度输入是通过将云解析模型（CRM）模拟的输出粗化到大小从8 × 8到256 × 256 km 2的子域上来提供的。然后，将小于子域尺度（w′h′ <$ZM）的基于ZM的湿静能垂直输送参数化与不同子域尺度的CRM模拟（w ′h′ <$CRM）直接计算结果进行比较。当子域尺寸从128 km减小到8 km时，集合平均w′h′ ′ CRM减小一半以上，而w′h′ ′ ZM仅在强对流情况下随子域尺寸减小，而在较弱情况下随子域尺寸增大。w′h′ ZM的分辨率依赖性取决于对流准平衡（QE）闭合中对流有效位能（CAPE）的正定网格尺度趋势。进一步的分析表明，CAPE（在取正定值之前）和w′h′ ′ CRM的实际网格尺度趋势随着子域大小的变化表现得非常相似，因为它们都与网格尺度平流趋势有关。我们可以通过在每个子域周围的适当大的区域上对CAPE的网格尺度趋势进行平均，然后再取其正定值，来显著改善w′h′ ′ ZM的分辨率依赖性。尽管集合平均w′h′ ′ CRM随着分辨率的增加而减小，但其变异性显著增加。w′h′ ′ ZM不能捕捉到这种变化的增加，这表明需要在相对较高的空间分辨率（8或16 km）下对对流进行随机处理。
To better understand the behavior of quasi‐equilibrium‐based convection parameterizations at higher resolution, we use a diagnostic framework to examine the resolution‐dependence of subgrid‐scale vertical transport of moist static energy as parameterized by the Zhang‐McFarlane convection parameterization (ZM). Grid‐scale input to ZM is supplied by coarsening output from cloud‐resolving model (CRM) simulations onto subdomains ranging in size from 8 × 8 to 256 × 256 km2. Then the ZM‐based parameterization of vertical transport of moist static energy for scales smaller than the subdomain size ( w′h′¯ZM ) are compared to those directly calculated from the CRM simulations ( w′h′¯CRM ) for different subdomain sizes. The ensemble mean w′h′¯CRM decreases by more than half as the subdomain size decreases from 128 to 8 km across while w′h′¯ZM decreases with subdomain size only for strong convection cases and increases for weaker cases. The resolution dependence of w′h′¯ZM is determined by the positive‐definite grid‐scale tendency of convective available potential energy (CAPE) in the convective quasi‐equilibrium (QE) closure. Further analysis shows the actual grid‐scale tendency of CAPE (before taking the positive definite value) and w′h′¯CRM behave very similarly as the subdomain size changes because they are both tied to grid‐scale advective tendencies. We can improve the resolution dependence of w′h′¯ZM significantly by averaging the grid‐scale tendency of CAPE over an appropriately large area surrounding each subdomain before taking its positive definite value. Even though the ensemble mean w′h′¯CRM decreases with increasing resolution, its variability increases dramatically. w′h′¯ZM cannot capture such increase in the variability, suggesting the need for stochastic treatment of convection at relatively high spatial resolution (8 or 16 km).
影响因子：
3.1
作者：
R. Plant;G. Craig
通讯作者：
R. Plant;G. Craig