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| Titel |
Experimental study of the formation of inverted-V structures and their stratification using AUREOL-3 observations |
| VerfasserIn |
O. Luízar, M. V. Stepanova, J. M. Bosqued, E. E. Antonova, R. A. Kovrazhkin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 18, no. 11 ; Nr. 18, no. 11, S.1399-1411 |
| Datensatznummer |
250014089
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| Publikation (Nr.) |
 copernicus.org/angeo-18-1399-2000.pdf |
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| Zusammenfassung |
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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