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| Titel |
Collective dynamics of bursty particle precipitation initiating in the inner and outer plasma sheet |
| VerfasserIn |
V. M. Uritsky, E. Donovan, A. J. Klimas, E. Spanswick |
| 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 ; 27, no. 2 ; Nr. 27, no. 2 (2009-02-16), S.745-753 |
| Datensatznummer |
250016410
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| Publikation (Nr.) |
 copernicus.org/angeo-27-745-2009.pdf |
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| Zusammenfassung |
| Using multiscale spatiotemporal analysis of bursty precipitation events in
the nighttime aurora as seen by the POLAR UVI instrument, we report a set of
new statistical signatures of high- and low-latitude auroral activity,
signaling a strongly non-uniform distribution of dissipation mechanism in the
plasma sheet. We show that small-scale electron emission events that
initiate in the equatorward portion of the nighttime auroral oval (scaling
mode A1) have systematically steeper power-law slopes of energy, power,
area, and lifetime probability distributions compared to the events that
initiate at higher latitudes (mode B). The low-latitude group of events
also contain a small but energetically important subpopulation of
substorm-scale disturbances (mode A2) described by anomalously low
distribution exponents characteristic of barely stable thermodynamic systems
that are prone to large-scale sporadic reorganization. The high latitude
events (mode ) can be accurately described by a single set of
distributions exponents over the entire range of studied scales, with the
exponent values consistent with globally stable self-organized critical (SOC)
behavior. The low- and high latitude events have distinct inter-trigger time
statistics, and are characterized by significantly different MLT
distributions. Based on these results we conjecture that the inner and outer
portions of the plasma sheet are associated with two (or more) mechanisms of
collective dynamics that may represent an interplay between current disruption and magnetic reconnection scenarios of bursty energy
conversion in the magnetotail. |
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