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Exploring parameterization for turbulent entrainment‐mixing processes in clouds
Author(s) -
Lu Chunsong,
Liu Yangang,
Niu Shengjie,
Krueger Steven,
Wagner Timothy
Publication year - 2013
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2012jd018464
Subject(s) - entrainment (biomusicology) , mixing (physics) , homogeneous , degree (music) , turbulence , statistical physics , scale (ratio) , meteorology , air entrainment , environmental science , physics , atmospheric sciences , mechanics , mathematics , quantum mechanics , rhythm , acoustics
Different turbulent entrainment‐mixing processes (e.g., homogeneous and inhomogeneous) occur in clouds; accurate representation of these processes is critical for improving cloud‐related parameterizations in large‐scale models, but poorly understood and quantified. Using in situ aircraft observations over the U. S. Department of Energy's Atmospheric Radiation Measurement Southern Great Plains site during the March 2000 Cloud Intensive Observation Period and numerical simulations with the Explicit Mixing Parcel Model (EMPM), here we explore the potential of using degree of homogeneous mixing as a measure to quantify these different mechanisms and examine various microphysical measures of homogeneous mixing degree and their relationships to entrainment‐mixing dynamics as measured by transition scale numbers. Three different microphysical measures for the homogeneous mixing degree are newly defined and each is coupled with one of two different transition scale numbers. Both observations and simulations show that all the combinations have positive correlated relationships; simulations further show that the tightest relationship is between the measure of homogeneous mixing degree considering adiabatic number concentration and the transition scale number accounting for mixing fraction of dry air. A parameterization of the entrainment‐mixing processes is advanced according to the relationships of homogeneous mixing degree measures to transition scale numbers.