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AGU: Geophysical Research Letters

 

Index Terms

  • Atmospheric Processes: Climate change and variability
  • Atmospheric Processes: Climatology
  • Atmospheric Processes: Convective processes
  • Atmospheric Processes: Mesoscale meteorology
  • Atmospheric Processes: Theoretical modeling

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L24813, 5 PP., 2005
doi:10.1029/2005GL024583

Observational evidence for exponential tornado intensity distributions over specific kinetic energy

Nikolai Dotzek

Institut für Physik der Atmosphäre, Deutsche Zentrum für Luft- und Raumfahrt, Wessling, Germany

Michael V. Kurgansky

Department of Geophysics, Faculty of Physical and Mathematical Sciences, Universidad de Concepción, Concepción, Chile

Jürgen Grieser

Deutsches Wetterdienst, Offenbach, Germany

Bernold Feuerstein

Max-Planck-Institut für Kernphysik, Heidelberg, Germany

Peter Névir

Institut für Meteorologie, Freie Universität Berlin, Berlin, Germany

Observational evidence supports the recent analytical prediction that tornado intensities are exponentially distributed over peak wind speed squared (v 2), or equivalently, Rayleigh-distributed over v. For large USA data samples, exponential tails are found in the tornado intensity distributions over v 2 from about F2 intensity on. Similar results follow for smaller worldwide data samples. For the 1990s data from the USA and Oklahoma, deviations from the Rayleigh distribution for weak tornadoes can be explained by the emergence of a separate, likely non-mesocyclonic tornado mode. These bimodal datasets can be modeled by superposition of two Rayleigh distributions. The change in modal dominance occurs at about the F2 threshold (v ≈ 50 m s−1). In France, likely mainly the mesocyclonic tornado mode has been recorded, while in the UK, only a non-mesocyclonic mode seems to be present.

Received 20 September 2005; accepted 17 November 2005; published 28 December 2005.

Citation: Dotzek, N., M. V. Kurgansky, J. Grieser, B. Feuerstein, and P. Névir (2005), Observational evidence for exponential tornado intensity distributions over specific kinetic energy, Geophys. Res. Lett., 32, L24813, doi:10.1029/2005GL024583.

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