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Eugene M. Wilkins and Chris J. Diamond


Experimental data and theory suggest that certain convection cell scale factors must be specified for correct interpretation of tornado simulations. The most important nondimensional number appears to be the ratio of convection cell depth (relating to height of vortex terminal region) to radius of the updraft. This scale factor has been ignored by most investigators, but it is especially important when comparing experimental results between two simulators or when relating simulator results to real tornadoes. Implications are discussed for possible cell geometry effects on tornadoes.

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Chris J. Diamond and Eugene M. Wilkins


A simulation of tornadoes translating over the ground was carried out in a modified Ward simulator. The purpose was to investigate the effects of translation on tornado dynamics. The results are as follows:

• Secondary vortexes were found to be generated by the relative motion between the main vortex and rough “ground.” The secondary vortexes trail the primary vortex. Apparently they feed off the energy of the primary vortex, and achieve a momentary transition state from a single vortex to multiple vortexes.

• The core radius increases with swirl ratio and decreases with surface roughness. Translation causes a local increase in swirl ratio, increasing the core size over that of a stationary vortex.

• The central pressure drop increases with swirl ratio during translation. Translation also causes a steeper pressure gradient on the trailing side of the vortex core. A similar characteristic tilt on the trailing side of the pressure profile has been noted on barograms for real tornadoes.

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Howard J. Diamond, Carl J. Schreck III, Emily J. Becker, Gerald D. Bell, Eric S. Blake, Stephanie Bond, Francis G. Bringas, Suzana J. Camargo, Lin Chen, Caio A. S. Coelho, Ricardo Domingues, Stanley B. Goldenberg, Gustavo Goni, Nicolas Fauchereau, Michael S. Halpert, Qiong He, Philip J. Klotzbach, John A. Knaff, Michelle L'Heureux, Chris W. Landsea, I.-I. Lin, Andrew M. Lorrey, Jing-Jia Luo, Kyle MacRitchie, Andrew D. Magee, Ben Noll, Richard J. Pasch, Alexandre B. Pezza, Matthew Rosencrans, Michael K. Tippet, Blair C. Trewin, Ryan E. Truchelut, Bin Wang, Hui Wang, Kimberly M. Wood, John-Mark Woolley, and Steven H. Young
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Stephen Baxter, Gerald D Bell, Eric S Blake, Francis G Bringas, Suzana J Camargo, Lin Chen, Caio A. S Coelho, Ricardo Domingues, Stanley B Goldenberg, Gustavo Goni, Nicolas Fauchereau, Michael S Halpert, Qiong He, Philip J Klotzbach, John A Knaff, Michelle L'Heureux, Chris W Landsea, I.-I Lin, Andrew M Lorrey, Jing-Jia Luo, Andrew D Magee, Richard J Pasch, Petra R Pearce, Alexandre B Pezza, Matthew Rosencrans, Blair C Trewin, Ryan E Truchelut, Bin Wang, H Wang, Kimberly M Wood, and John-Mark Woolley
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