Abstract
It is suggested that the downward helicity flux (through the upper boundary of the viscous turbulent boundary layer) be treated as a measure of the intensity of atmospheric vortices, including tropical cyclones, tornadoes, and dust devils. As follows immediately from the general helicity balance equation known in the literature, this flux is determined by the product of the cubed maximum wind speed and the width of the strip swept by the maximum wind during vortex movement. For intense vortices in their steady-state, mature stage, this helicity flux can also serve as a measure of the rate of helicity destruction by the forces of viscous turbulent friction. Examples of applying the introduced notion to the diagnostics of tornadoes and their classification according to a destructive force are given. A comparative analysis (according to helicity flux values) of dust devils on the Earth and Mars, on the one hand, and tornadoes, on the other, is presented.
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Original Russian Text © M.V. Kurgansky, 2008, published in Izvestiya AN. Fizika Atmosfery i Okeana, 2008, Vol. 44, No. 1, pp. 67–74.
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Kurgansky, M.V. Vertical helicity flux in atmospheric vortices as a measure of their intensity. Izv. Atmos. Ocean. Phys. 44, 64–71 (2008). https://doi.org/10.1134/S0001433808010076
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DOI: https://doi.org/10.1134/S0001433808010076