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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 18, issue 11
Ann. Geophys., 18, 1399–1411, 2000
https://doi.org/10.1007/s00585-000-1399-6
© European Geosciences Union 2000
Ann. Geophys., 18, 1399–1411, 2000
https://doi.org/10.1007/s00585-000-1399-6
© European Geosciences Union 2000

  30 Nov 2000

30 Nov 2000

Experimental study of the formation of inverted-V structures and their stratification using AUREOL-3 observations

O. Luízar2,1, M. V. Stepanova2, J. M. Bosqued3, E. E. Antonova4, and R. A. Kovrazhkin5 O. Luízar et al.
  • 1Departamento de Física, Universidad Nacional San Antonio Abad del Cusco, Peru
  • 2Departamento de Física, Universidad de Santiago de Chile, Casilla 307, Santiago, Chile
  • 3Centre d'Etude Spatiale des Rayonnements , CNRS/UPS, BP 4346, 31028 Toulouse, France
  • 4Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow 119899, Vorobievi Gori, Russia
  • 5Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, Moscow 117810, Russia

Abstract. Multiple inverted-V structures are commonly observed on the same auroral zone crossing by a low-altitude orbiting satellite. Such structures appear grouped and apparently result from an ionospheric and/or magnetospheric mechanism of stratification. More than two years of AUREOL-3 satellite observations were analyzed to study their properties and their formation in the framework of the ionosphere-magnetosphere coupling model proposed by Tverskoy. This model predicts some natural periodicity in the electrostatic potential profile (and subsequently in the field-aligned current profiles) that could account for oscillations experimentally observed in the auroral zone, such as successive inverted-Vs. Experimental results obtained during quiet or moderately active periods demonstrate that the number of structures observed within a given event is well described by a 'scaling' parameter provided by the hot plasma stratification theory and expressed in terms of the field-aligned current density, the total width of the current band, the plasma sheet ion temperature, and the height-integrated Pedersen conductivity of the ionosphere. The latitudinal width, in the order of 100–200 km at ionospheric altitudes, is relatively independent of the current density, and is determined not only by the existence of a potential difference above the inverted-Vs, but also by basic oscillations of the ionosphere-magnetosphere coupling system predicted by Tverskoy. The large number of cases studied by the AUREOL-3 satellite provides reliable statistical trends which permits the validation of the model and the inference that the multiple structures currently observed can be related directly to oscillations of the magnetospheric potential (or the pressure gradients) on a scale of ~1000-2000 km in the near-Earth plasma sheet. These oscillations arise in the Tverskoy model and may naturally result when the initial pressure gradients needed to generate a large-scale field-aligned current have a sufficiently wide equatorial scale, of about 1 RE or more.

Key words: Magnetospheric physics (current systems; energetic particles, precipitating; magnetosphere-ionosphere interactions)

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