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DOI	10.1029/2019JD032017
	The Contributions of Shear and Turbulence to Cloud Overlap for Cumulus Clouds
	Sulak A.M.; Calabrase W.J.; Ryan S.D.; Heus T.
发表日期	2020
ISSN	2169897X
卷号	125 期号:10
英文摘要	The causes of vertical cloud overlap, the ratio between the cloud fraction by area and the cloud fraction by volume, are studied for fields of cumulus convection. Using large-eddy simulations, the structure of individual clouds within the cloud field is inspected and connected to the overall cloud cover of the entire cloud field. First, it is shown that the cloud overlap of the entire field can be well approximated by the total cloud overlap of the individual clouds. It is then shown that a simple maximum overlap assumption, which is commonly used for cloud fields with small layer depth, can only account for roughly half of the overlap inefficiency. This is due to the fact that maximum overlap only represents variations in cloud width as a function of depth but does not take other factors into account, most notably shear or turbulence. The effects of turbulence and wind shear on the overlap of individual clouds are first estimated as a function of cloud depth, which closes the discrepancy between observed cloud overlap and the maximum overlap assumption. Then, an empirical model is developed for the shear and turbulence contributions on overlap as a function of cloud depth and of synoptic conditions. Finally, it is shown that our model is capable of accurately predicting overlap for a large number of cloud fields and under a variety of meteorological conditions. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	Cumulus; Large Eddy Simulations; Overlap; Parameterization
语种	英语
来源期刊	Journal of Geophysical Research: Atmospheres
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/186011
作者单位	Department of Physics, Cleveland State University, Cleveland, OH, United States; Department of Mathematics and Statistics, Cleveland State University, Cleveland, OH, United States; Department of Mathematics, Michigan State University, East Lansing, MI, United States; Department of Physics, Case Western Reserve University, Cleveland, OH, United States
推荐引用方式 GB/T 7714	Sulak A.M.,Calabrase W.J.,Ryan S.D.,et al. The Contributions of Shear and Turbulence to Cloud Overlap for Cumulus Clouds[J],2020,125(10).
APA	Sulak A.M.,Calabrase W.J.,Ryan S.D.,&Heus T..(2020).The Contributions of Shear and Turbulence to Cloud Overlap for Cumulus Clouds.Journal of Geophysical Research: Atmospheres,125(10).
MLA	Sulak A.M.,et al."The Contributions of Shear and Turbulence to Cloud Overlap for Cumulus Clouds".Journal of Geophysical Research: Atmospheres 125.10(2020).