Computational Domain Size Effects on Large-Eddy Simulations of Precipitating Shallow Cumulus Convection
Computational Domain Size Effects on Large-Eddy Simulations of Precipitating Shallow Cumulus Convection
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DOI：
10.3390/atmos14071186
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发表时间：
2023-07
期刊：
影响因子：
2.9
通讯作者：
Oumaima Lamaakel;R. Venters;João Paulo Ramos Teixeira;G. Matheou
中科院分区：
文献类型：
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作者：
Oumaima Lamaakel;R. Venters;João Paulo Ramos Teixeira;G. Matheou
浅层对流的理想化大涡模拟通常采用水平周期性的计算区域。浅积云对流中降水的发展改变了对流的空间结构，产生了大尺度的组织。然而，有限的周期域限制了大气边界层的水平变化。小的计算域不能捕获中尺度边界层组织和人为地约束水平对流结构。采用40× 40 ~ 320× 320 km ~ 2的四个计算区域，在细网格分辨率（40 m）下，研究了水平区域大小对浅降水积云对流大涡模拟的影响。边界层的水平变化在160× 160 km 2的计算区域内被捕获。小的LES区域（≤40 km）不能再现长约100 km的中尺度气流特征，但边界层平均廓线与大的LES区域相似。对于大于或等于160× 160 km 2的区域，湍流通量、温度和湿度方差以及水平长度尺度相对于区域大小是收敛的。垂直速度流的统计，如方差和频谱，基本上是相同的，在所有领域，并显示较小的依赖域的大小。特征水平长度尺度（即，水平风分量、温度和湿度在大约30小时后达到平衡。
Idealized large-eddy simulations of shallow convection often utilize horizontally periodic computational domains. The development of precipitation in shallow cumulus convection changes the spatial structure of convection and creates large-scale organization. However, the limited periodic domain constrains the horizontal variability of the atmospheric boundary layer. Small computational domains cannot capture the mesoscale boundary layer organization and artificially constrain the horizontal convection structure. The effects of the horizontal domain size on large-eddy simulations of shallow precipitating cumulus convection are investigated using four computational domains, ranging from 40×40km2 to 320×320km2 and fine grid resolution (40 m). The horizontal variability of the boundary layer is captured in computational domains of 160×160km2. Small LES domains (≤40 km) cannot reproduce the mesoscale flow features, which are about 100km long, but the boundary layer mean profiles are similar to those of the larger domains. Turbulent fluxes, temperature and moisture variances, and horizontal length scales are converged with respect to domain size for domains equal to or larger than 160×160km2. Vertical velocity flow statistics, such as variance and spectra, are essentially identical in all domains and show minor dependence on domain size. Characteristic horizontal length scales (i.e., those relating to the mesoscale organization) of horizontal wind components, temperature and moisture reach an equilibrium after about hour 30.