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| Titel |
Correlated Interball/ground-based observations of isolated substorm: The pseudobreakup phase |
| VerfasserIn |
A. G. Yahnin, V. A. Sergeev, T. Bösinger, T. I. Sergienko, I. A. Kornilov, N. L. Borodkova, M. F. Thomsen, R. D. Belian, J.-A. Sauvaud, V. N. Lutsenko, A. A. Skalsky |
| 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 ; 19, no. 7 ; Nr. 19, no. 7, S.687-698 |
| Datensatznummer |
250014281
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| Publikation (Nr.) |
 copernicus.org/angeo-19-687-2001.pdf |
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| Zusammenfassung |
We study the isolated
substorm that occurred after a long quiet period, which showed all of the
substorm signatures except for the first half hour of the expansion phase,
which could be characterized as a pseudobreakup sequence, rather than a
full-scale substorm onset. During the considered event, the substorm’s
instability leads to a current disruption, which starts at the near-Earth
plasma sheet and then propagates tailward. Based on auroral observations, the
analysis of geosynchronous plasma injections, and the plasma sheet observations
at ~15 RE at the meridian of auroral substorm development we show that (1)
before and probably during "pseudobreakup phase", the plasma sheet
stayed cold and dense, (2) during the pseudobreakup phase, particle injections
at 6.6 RE were only seen in unusually low energy components, and (3) the
electron precipitation into the ionosphere was very soft. We conclude that the
basic difference between pseudobreakups and "real" substorm
activations was found in the low energy of all manifestations. We suggest that
high density and low electron temperature in the plasma sheet are the reasons
for low energization in the magnetic reconnection operated on closed field
lines in the plasma sheet, as well as the weak field-aligned acceleration, as
predicted by the Knight’s relationship. The low Hall conductivity could then
be the reason for the weak ground magnetic effects observed. This explanation
suggests that the role of the ionospheric conductivity is "passive"
as the plasma sheet, rather than the ionosphere, controls the development of
the magnetospheric instability.
Key words. Ionosphere (particle
precipitation) – Magnetospheric physics (auroral phenomena; plasma sheet) |
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