Determining the fine structure of the entrainment zone in cloud-topped boundary layers
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Authors
Horner, Michael S.
Subjects
Cloud-top entrainment
Entrainment-zone structure
Aircraft measurements
ASTEX
Entrainment zone
Inhomogeneous mixing
Entrainment mixing fraction
Entrainment-zone structure
Aircraft measurements
ASTEX
Entrainment zone
Inhomogeneous mixing
Entrainment mixing fraction
Advisors
Wang, Qing
Wash, Carlyle H.
Date of Issue
2005-03
Date
March 2005
Publisher
Monterey California. Naval Postgraduate School
Language
Abstract
The objective of this thesis is to obtain a better understanding of cloud-top entrainment through an in-depth analysis of entrainment-zone structure. In situ aircraft measurements taken during the Atlantic Stratocumulus Transition Experiment (ASTEX) were used for this purpose. Using data collected from multiple cloud-top penetrations, the presence of an interfacial layer in-between the top of the cloud mixed-layer and the base of the free atmosphere is identified and consequently defined as the entrainment zone. The depth of the entrainment zone is on the order of tens of meters, where turbulence and sometimes cloud droplets are detectable. Inhomogeneous mixing was found to occur within the entrainment zone. Parcels of inversion-layer air and boundary-layer air are identified within the entrainment zone. Analyses suggest that turbulence intensity and cloud amount in the entrainment zone vary depending on the distribution of entrainment mixing fraction. Furthermore, continuous mixing in the entrainment zone appears to dissipate the upper-cloud layer. However, continuous dissipation of the upper-cloud layer has not been observed. Further study is needed to determine the interaction between cloud-top entrainment and the full integration of boundary-layer dynamics.
Type
Thesis
Description
Series/Report No
Department
Department of Meteorology
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
xvi, 75 p. : ill. (some col.)
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.