The dynamics of persistent cold-air pool breakup

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Title The dynamics of persistent cold-air pool breakup
Publication Type dissertation
School or College College of Mines & Earth Sciences
Department Atmospheric Sciences
Author Lareau, Neil P.
Date 2014-08
Description The wind-induced disruption and breakup of multiday cold-air pools are investigated using observational analyses and idealized numerical simulations. The observations are from the Persistent Cold-Air Pool (CAP) Study, which provides modern measurement of the meteorological processes affecting the duration of cold-air pools in the Salt Lake Valley of Utah. In general, the observations indicate that synoptic-scale processes control cold-air pool duration while local processes affect near-surface stratification and mixing. The most common form of CAP breakup is due to cold-air advection aloft. However, analyses reveal that some cold-air pools are destroyed or disrupted by strong winds penetrating into the valley. The resulting wind-CAP interactions are complex, involving sequential CAP displacements, internal oscillations, dynamic instabilities, and terrainflow interactions. Large Eddy Simulations of multiday cold-air pools in idealized valley topography further demonstrate that cold-air pool removal is affected by the interplay of Kelvin-Helmholtz instability and warm air advection. This dynamic instability generates breaking waves in the stratified shear flow that mix cold-air into the warmer flow aloft. Variations in the initial cold pool stratification and valley terrain affect the timescale for cold-air pool removal. Despite these variations, a basic relationship between the magnitude of the flow aloft and the strength of the underlying cold-air pool can be expressed in terms of the "CAP Froude number." This dimensionless quantity is useful for diagnosing the onset and amplification of turbulent mixing, as well as the complete removal of cold-air pools.
Type Text
Publisher University of Utah
Subject Cold-air pool; Inversion; Turbulent mixing
Dissertation Institution University of Utah
Dissertation Name Doctor of Philosophy
Language eng
Rights Management Copyright © Neil P. Lareau 2014
Format application/pdf
Format Medium application/pdf
Format Extent 2,654,291 bytes
Identifier etd3/id/3110
ARK ark:/87278/s6vh8x2j
Setname ir_etd
ID 196678
Reference URL https://collections.lib.utah.edu/ark:/87278/s6vh8x2j
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