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Chinese Science Bulletin

, Volume 58, Issue 4–5, pp 545–551 | Cite as

A method for distinguishing and linking turbulent entrainment mixing and collision-coalescence in stratocumulus clouds

  • ChunSong Lu
  • YanGang Liu
  • ShengJie Niu
Open Access
Article Atmospheric Science

Abstract

This paper presents a method to distinguish and link inhomogeneous mixing with subsequent ascent and collision-coalescence. Three stratocumulus clouds analyzed were collected over the U.S. Department of Energy’s Atmospheric Radiation Measurement Southern Great Plains site during the March 2000 cloud Intensive Observation Period. The criteria are presented to distinguish the two processes. Inhomogeneous mixing with subsequent ascent is identified if cloud along an aircraft horizontal leg is non-drizzling and the relationship between cloud volume-mean radius and liquid water content is negative; in contrast, drizzling and positive relationship between the above two properties are the criteria for collision-coalescence. To link the two processes, threshold function, the possibility of occurrence of collision-coalescence, is employed; the big droplets generated during the inhomogeneous mixing with subsequent ascent increase the threshold function, initiates collision-coalescence and produces drizzle drops. To the authors’ knowledge, this is the first study on distinguishing and linking inhomogeneous mixing with subsequent ascent and collision-coalescence based on observational data.

Keywords

entrainment-mixing process collision-coalescence stratocumulus warm rain initiation drizzle 

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Copyright information

© The Author(s) 2012

Authors and Affiliations

  1. 1.Key Laboratory for Atmospheric Physics and Environment of China Meteorological Administration, Key Laboratory of Meteorological Disaster of Ministry of EducationNanjing University of Information Science and TechnologyNanjingChina
  2. 2.Atmospheric Sciences DivisionBrookhaven National LaboratoryNew YorkUSA

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