Statistics of Small-Scale Velocity Fluctuations and Internal Intermittency in Marine Stratocumulus Clouds

Author:

Siebert H.1,Shaw R. A.2,Warhaft Z.3

Affiliation:

1. Leibniz Institute for Tropospheric Research, Leipzig, Germany

2. Leibniz Institute for Tropospheric Research, Leipzig, Germany, and Department of Physics, Michigan Technological University, Houghton, Michigan

3. Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York

Abstract

Abstract Clouds are known to be turbulent, but the details of their internal turbulent structure have been largely unexplored. Measurements of turbulent velocities in stratocumulus clouds presented here reveal an intermittent structure consistent with that observed in classic homogeneous isotropic turbulence. The measurements were taken close to cloud top in a 200-m-thick cloud layer over a path of approximately 6 km, using a hot-wire anemometer below a helicopter as part of the Airborne Cloud Turbulence Observation System (ACTOS) measurement system. Hot-wire signal artifacts resulting from droplet impacts are removed without significantly degrading the signal, such that high-order velocity structure functions can be evaluated. The structure function analysis for orders 2–8 show statistically significant departures from the Kolmogorov’s 1941 scaling, yielding scaling exponents consistent with the Kolmogorov–Obukhov refined similarity hypothesis, with an intermittency exponent of 0.25. This is in agreement with the accepted value determined in single-phase flows under carefully controlled conditions, and no evidence is found of any departure from the large body of knowledge obtained from the laboratory on the finescale turbulence structure. This suggests that processes depending on the finescale structure of turbulence that cannot presently be measured in clouds can be explored in the laboratory setting. Since these findings pertain to clouds with relatively low liquid water content and weak turbulence, further work will be required to determine their applicability to other cloud types.

Publisher

American Meteorological Society

Subject

Atmospheric Science

Cited by 41 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3