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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 21, issue 8
Ann. Geophys., 21, 1839-1845, 2003
https://doi.org/10.5194/angeo-21-1839-2003
© Author(s) 2003. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 21, 1839-1845, 2003
https://doi.org/10.5194/angeo-21-1839-2003
© Author(s) 2003. This work is distributed under
the Creative Commons Attribution 3.0 License.

  31 Aug 2003

31 Aug 2003

Turbulence characteristics inside ionospheric small-scale expanding structures observed with SuperDARN HF radars

R. André, C. Hanuise, J.-P. Villain, and V. Krasnoselskikh R. André et al.
  • LPCE/CNRS, 3A Av. de la Recherche Scientifique, 45071 Orléans Cedex, France

Abstract. Unusual structures characterized by a very high-velocity divergence have been observed in the high-latitude F-region with SuperDARN radars (André et al., 2000). These structures have been interpreted as due to local demagnetization of the plasma in the ionospheric F-region, during very specific geophysical conditions. In this study, the collective wave scattering theory is used to characterize the decameter-scale turbulence (l approx 15 m) inside the structures. The distribution function of the diffusion coefficient is modified when the structures are generated, suggesting that two regimes of turbulence coexist. A temporal analysis decorrelates the two regimes and gives access to the dynamics associated with the structures. It is shown that a high turbulent regime precedes the plasma demagnetization and should be related to an energy deposition. Then a second regime appears when the plasma is demagnetized and disappears simultaneously with the structures. This study is the first application of the collective wave scattering theory to a specific geophysical event.

Key words. Ionosphere (auroral ionosphere; ionospheric irregularities) – Space plasma physics (turbulence)

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