The origins of vortex sheets in a simulated supercell thunderstorm

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

This paper investigates the origins of the (cyclonic) vertical vorticity within vortex sheets that develop within a numerically simulated supercell in a nonrotating, horizontally homogeneous environment with a free-slip lower boundary. Vortex sheets are commonly observed along the gust fronts of supercell storms, particularly in the early stages of storm development. The "collapse" of a vortex sheet into a compact vortex is often seen to accompany the intensification of rotation that occasionally leads to tornadogenesis. The vortex sheets predominantly acquire their vertical vorticity from the tilting of horizontal vorticity that has been modified by horizontal buoyancy gradients associated with the supercell's cool low-level outflow. If the tilting is within an ascending airstream (i.e., the horizontal gradient of vertical velocity responsible for the tilting resides entirely within an updraft), the vertical vorticity of the vortex sheet nearly vanishes at the lowest model level for horizontal winds (5 m). However, if the tilting occurs within a descending airstream (i.e., the horizontal gradient of vertical velocity responsible for tilting includes a downdraft adjacent to the updraft within which the majority of the cyclonic vorticity resides), the vortex sheet extends to the lowest model level. The findings are consistent with the large body of prior work that has found that downdrafts are necessary for the development of significant vertical vorticity at the surface.

Original languageEnglish (US)
Pages (from-to)3944-3954
Number of pages11
JournalMonthly Weather Review
Volume142
Issue number11
DOIs
StatePublished - Jan 1 2014

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supercell
thunderstorm
vortex
vorticity
updraft
gust
buoyancy
outflow

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Cite this

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The origins of vortex sheets in a simulated supercell thunderstorm. / Markowski, Paul; Richardson, Yvette; Bryan, George.

In: Monthly Weather Review, Vol. 142, No. 11, 01.01.2014, p. 3944-3954.

Research output: Contribution to journalArticle

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