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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 23, issue 4
Ann. Geophys., 23, 1455–1465, 2005
https://doi.org/10.5194/angeo-23-1455-2005
© Author(s) 2005. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 23, 1455–1465, 2005
https://doi.org/10.5194/angeo-23-1455-2005
© Author(s) 2005. This work is distributed under
the Creative Commons Attribution 3.0 License.

  03 Jun 2005

03 Jun 2005

Excitation of Alfvén impulse by the anomalous resistance onset on the auroral field lines

V. Pilipenko1, N. Mazur1, E. Fedorov1, T. Uozumi2, and K. Yumoto2 V. Pilipenko et al.
  • 1Institute of the Physics of the Earth, Moscow, Russia
  • 2Space Environment Research Center, Kyushu University, Fukuoka, Japan

Abstract. The onset of anomalous resistance in a layer on auroral field lines is shown to be accompanied by the excitation of an Alfvénic impulse (AI). The generated AI marks the transition of the global magnetosphere-ionosphere instability into an explosive phase with positive feedback. The spatial structure of this impulse both in space and on the ground has been described analytically and numerically under the thin layer approximation. The field-aligned currents transported by the Alfvénic impulse are concentrated near the edges of the layer with anomalous resistivity, whereas the reverse currents are spread throughout the layer. For some parameters of the layer the ionospheric attenuation of even small-scale structures is not dramatically large, so the magnetic response to the generated AI may be observed on the ground. The considered event on 3 January 1997 with magnetic-auroral intensification observed by ground magnetometers and Polar UV imager agrees with the model proposed.

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