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DOI	10.1029/2019MS001976
	A Bound on Ekman Pumping
	de Roode S.R.; Siebesma A.P.
发表日期	2020
ISSN	19422466
卷号	12 期号:3
英文摘要	Momentum transport by boundary layer turbulence causes a weak synoptic-scale vertical motion. The classical textbook solution for the strength of this Ekman pumping depends on the curl of the surface momentum flux. A new solution for Ekman pumping is derived in terms of the curl of the geostrophic wind and a term that depends in a nontrivial way on the vertical profile of the turbulent momentum flux. The solution is confined to a boundary layer regime that is vertically well mixed and horizontally homogeneous. The momentum flux is computed from a commonly used bulk surface drag formula and a flux jump relation to capture the entrainment flux of momentum at the top of the boundary layer. It is found that the strength of Ekman pumping is bounded. The weakening of Ekman pumping for enhanced turbulent surface friction can be explained from the fact that it will reduce the magnitude of the horizontal wind. It is demonstrated that entrainment of momentum across the top of the boundary layer tends to diminish the large-scale divergence of the wind. As momentum transport is parameterized in large-scale models, the analysis is relevant for the understanding and interpretation of the evolution of synoptic-scale vertical motions as predicted by such models. © 2020. The Authors.
英文关键词	Ekman pumping; large-scale divergence; large-scale subsidence; turbulent friction; turbulent momentum transport
语种	英语
scopus关键词	Boundary layers; Friction; Momentum; Momentum transfer; Pumps; Boundary layer turbulence; Ekman pumping; large-scale divergence; Large-scale models; Momentum transports; Textbook solutions; Turbulent momentum; Turbulent momentum fluxes; Atmospheric thermodynamics; boundary layer; drag; Ekman pumping; friction; geostrophic flow; momentum transfer; subsidence; synoptic meteorology; turbulence
来源期刊	Journal of Advances in Modeling Earth Systems
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/156755
作者单位	Faculty of Civil Engineering and Geosciences, Department of Geoscience and Remote Sensing, Delft University of Technology, Delft, Netherlands; KNMI, De Bilt, Netherlands
推荐引用方式 GB/T 7714	de Roode S.R.,Siebesma A.P.. A Bound on Ekman Pumping[J],2020,12(3).
APA	de Roode S.R.,&Siebesma A.P..(2020).A Bound on Ekman Pumping.Journal of Advances in Modeling Earth Systems,12(3).
MLA	de Roode S.R.,et al."A Bound on Ekman Pumping".Journal of Advances in Modeling Earth Systems 12.3(2020).