Horizontal Vortex Tubes near a Simulated Tornado: Three-Dimensional Structure and Kinematics

Supercell thunderstorms can produce a wide spectrum of vortical structures, ranging from midlevel mesocyclones to small-scale suction vortices within tornadoes. A less documented class of vortices are horizontally-oriented vortex tubes near and/or wrapping about tornadoes, that are observed either v...

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Bibliographic Details
Published inAtmosphere Vol. 10; no. 11; p. 716
Main Authors Oliveira, Maurício I., Xue, Ming, Roberts, Brett J., Wicker, Louis J., Yussouf, Nusrat
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.11.2019
Subjects
Computational fluid dynamics
Digital video recorders
Doppler radar
Doppler radar data
Doppler sonar
Downdraft
Fluid flow
Friction
horizontal vortices
Kinematics
Mathematical models
numerical simulation
Numerical simulations
Outflow
Radar
Radar data
Regions
Simulation
Suction
supercell
Supercell thunderstorms
Surface wind
Three dimensional analysis
Thunderstorms
Tornadoes
Tubes
Updraft
Visual observation
visualization
Vortices
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Summary:Supercell thunderstorms can produce a wide spectrum of vortical structures, ranging from midlevel mesocyclones to small-scale suction vortices within tornadoes. A less documented class of vortices are horizontally-oriented vortex tubes near and/or wrapping about tornadoes, that are observed either visually or in high-resolution Doppler radar data. In this study, an idealized numerical simulation of a tornadic supercell at 100 m grid spacing is used to analyze the three-dimensional (3D) structure and kinematics of horizontal vortices (HVs) that interact with a simulated tornado. Visualizations based on direct volume rendering aided by visual observations of HVs in a real tornado reveal the existence of a complex distribution of 3D vortex tubes surrounding the tornadic flow throughout the simulation. A distinct class of HVs originates in two key regions at the surface: around the base of the tornado and in the rear-flank downdraft (RFD) outflow and are believed to have been generated via surface friction in regions of strong horizontal near-surface wind. HVs around the tornado are produced in the tornado outer circulation and rise abruptly in its periphery, assuming a variety of complex shapes, while HVs to the south-southeast of the tornado, within the RFD outflow, ascend gradually in the updraft.
ISSN:2073-4433
2073-4433
DOI:10.3390/atmos10110716