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Numerical Simulation of Tornado-like Vortices Induced by Small-Scale Cyclostrophic Wind Perturbations
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  • Yuhan Liu,
  • Yongqiang Jiang,
  • Chaohui Chen,
  • Yun Zhang,
  • Hongrang He,
  • Xiong Chen,
  • ruilin Zhong
Yuhan Liu
National University of Defense Technology

Corresponding Author:[email protected]

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Yongqiang Jiang
College of Meteorology and Oceanography, National University of Defense Technology
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Chaohui Chen
National University of Defense Technology
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Yun Zhang
College of Meteorology and Oceanography, National University of Defense Technology
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Hongrang He
College of Meteorology and Oceanography, National University of Defense Technology
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Xiong Chen
College of Meteorology and Oceanography, National University of Defense Technology
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ruilin Zhong
National University of Defense Technology
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Abstract

This study introduces a tornado perturbation model utilizing the cyclostrophic wind model, implemented through a shallow-water equation framework. We conducted numerical simulations to examine development of perturbations within a static atmosphere background. Four numerical experiments were conducted: a single cyclonic wind perturbation (EXP1), a single low-geopotential height perturbation (EXP2), a cyclonic wind perturbation with a 0 Coriolis parameter (EXP3), and a single anticyclonic wind perturbation (EXP4). The outputs of these experiments were analyzed using comparative methods. In a static atmosphere setting, EXP1 generated a tornado-like pressure structure under a small-scale cyclonic wind perturbation. The centrifugal force in the central area exceeded the pressure gradient force, causing air particles to flow outward, leading to a pressure drop and strong pressure gradient. EXP2 induced a purely radial wind field; upon initiation, the central area exhibited convergence, and the geopotential height increased rapidly, indicating that a small-scale depression is insufficient to generate a tornado’s vortex flow field. EXP3’s results, with a 0 Coriolis parameter, are marginally different from EXP1, suggesting the Coriolis force’s negligible impact on small-scale movements. EXP4 demonstrates that a small-scale anticyclonic wind field perturbation can also trigger tornado-like phenomena akin to EXP1. The results indicate that a robust cyclonic and an anticyclonic wind field can potentially generate a pair of cyclonic and anticyclonic tornadoes, when the horizontal vortex tubes in an atmosphere with strong vertical wind shear tilt, forming a pair of positive and negative vorticities. These tornadoes are similar but have different rotation directions.
10 Jan 2024Submitted to ESS Open Archive
02 Feb 2024Published in ESS Open Archive