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| Titel |
Different magnetospheric modes: solar wind driving and coupling efficiency |
| VerfasserIn |
N. Partamies, T. I. Pulkkinen, R. L. McPherron, K. McWilliams, C. R. Bryant, E. Tanskanen, H. J. Singer, G. D. Reeves, M. F. Thomsen |
| 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. 11 ; Nr. 27, no. 11 (2009-11-16), S.4281-4291 |
| Datensatznummer |
250016710
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| Publikation (Nr.) |
 copernicus.org/angeo-27-4281-2009.pdf |
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| Zusammenfassung |
| This study describes a systematic statistical comparison of isolated
non-storm substorms, steady magnetospheric convection (SMC) intervals and
sawtooth events. The number of events is approximately the same in each group
and the data are taken from about the same years to avoid biasing by
different solar cycle phase. The very same superposed epoch analysis is
performed for each event group to show the characteristics of ground-based
indices (AL, PCN, PC potential), particle injection at the geostationary
orbit and the solar wind and IMF parameters. We show that the monthly
occurrence of sawtooth events and isolated non-stormtime substorms closely
follows maxima of the geomagnetic activity at (or close to) the equinoxes.
The most strongly solar wind driven event type, sawtooth events, is the least
efficient in coupling the solar wind energy to the auroral ionosphere, while
SMC periods are associated with the highest coupling ratio (AL/EY).
Furthermore, solar wind speed seems to play a key role in determining the
type of activity in the magnetosphere. Slow solar wind is capable of
maintaining steady convection. During fast solar wind streams the
magnetosphere responds with loading–unloading cycles, represented by
substorms during moderately active conditions and sawtooth events (or other
storm-time activations) during geomagnetically active conditions. |
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