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Title:Controls of updraft size, cold pool characteristics, and potential tornado intensity in supercell thunderstorms
Author(s):Marion, Geoffrey R
Advisor(s):Trapp, Robert J.
Department / Program:Atmospheric Sciences
Discipline:Atmospheric Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Cold pool
Abstract:While the overall understanding of moist convective processes has advanced greatly, the two-way interconnections between convection initiation, updraft structure, and subsequent cold pool generation are not well understood. This has become particularly relevant with ongoing efforts to introduce cold pool processes in convective parameterization schemes. Here, the structure of supercell updraft width and its connection to attendant cold pool characteristics are examined using idealized simulations. This study finds that, within a supercell storm mode, updraft width is strongly dependent on environmental vertical wind shear, dependent on the boundary layer depth (as well as corresponding changes to CAPE) of the storm environment, yet relatively insensitive to the characteristics of convection initiation mechanisms. This study also find that the processes that may lead to the formation of particularly intense tornadoes are modulated by updraft width. Specifically, a simple hypothesis is proposed that larger, more intense tornadoes should more readily form from wider rotating updrafts. This hypothesis is tested using idealized simulations, which reveal strong correlations between updraft width and low-level vorticity that support this hypothesis. These simulations are also used to explore how quantifications of convective overshoots could help identify storms with the potential to form strong tornadoes. In particular, it is shown that the peak area of an overshooting top correlates strongly to the peak area of the mid-level updraft.
Issue Date:2017-04-27
Rights Information:Copyright 2017 Geoffrey Marion
Date Available in IDEALS:2017-08-10
Date Deposited:2017-05

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