气候变化领域集成服务门户(CCPortal): Effects of Surface and Top Wind Shear on the Spatial Organization of Marine Stratocumulus-Topped Boundary Layers

CCPortal

DOI	10.1029/2020JD034162
	Effects of Surface and Top Wind Shear on the Spatial Organization of Marine Stratocumulus-Topped Boundary Layers
	Zamora Zapata M.; Heus T.; Kleissl J.
发表日期	2021
ISSN	2169897X
卷号	126 期号:11
英文摘要	The convective nature of Stratocumulus topped boundary layers (STBL) involves the motion of updrafts and downdrafts, driven by surface fluxes and radiative cooling, respectively. The balance between shear and buoyant forcings at the surface can determine the organization of updrafts between cellular and roll structures. We investigate the effect of varying shear at the surface and top of the STBL using Large Eddy Simulations, taking DYCOMS II RF01 as a base case. We focus on spatial identification of the following features: coherent updrafts and downdrafts, and observe how they are affected by varying shear. Stronger surface shear organizes the updrafts in rolls, causes less well-mixed thermodynamic profiles, and decreases cloud fraction and liquid water path (LWP). Stronger top shear also decreases cloud fraction and LWP more than surface shear, by thinning the cloud from the top. Features with stronger top than surface shear are associated with a net downward momentum transport and show early signs of decoupling. Classifying updrafts and downdrafts based on their vertical span and horizontal size confirms the dominance of tall objects spanning the whole STBL. Tall objects occupy 30% of the volume in the STBL, while short ones occupy less than 1%. For updraft and downdraft fluxes, these tall objects explain 65% of the vertical velocity variance and 83% of the buoyancy flux, on average. Stronger top shear also weakens the contribution of downdrafts to the turbulent fluxes and tilts the otherwise vertical development of updrafts. © 2021. American Geophysical Union. All Rights Reserved.
英文关键词	coherent structures; Spatial organization; Stratocumulus; Wind shear
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/185169
作者单位	Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, United States; Department of Physics, Cleveland State University, Cleveland, OH, United States
推荐引用方式 GB/T 7714	Zamora Zapata M.,Heus T.,Kleissl J.. Effects of Surface and Top Wind Shear on the Spatial Organization of Marine Stratocumulus-Topped Boundary Layers[J],2021,126(11).
APA	Zamora Zapata M.,Heus T.,&Kleissl J..(2021).Effects of Surface and Top Wind Shear on the Spatial Organization of Marine Stratocumulus-Topped Boundary Layers.Journal of Geophysical Research: Atmospheres,126(11).
MLA	Zamora Zapata M.,et al."Effects of Surface and Top Wind Shear on the Spatial Organization of Marine Stratocumulus-Topped Boundary Layers".Journal of Geophysical Research: Atmospheres 126.11(2021).