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| Titel |
Statistical properties of substorms during different storm and solar cycle phases |
| VerfasserIn |
N. Partamies, L. Juusola, E. Tanskanen, K. Kauristie |
| 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 ; 31, no. 2 ; Nr. 31, no. 2 (2013-02-27), S.349-358 |
| Datensatznummer |
250018997
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| Publikation (Nr.) |
 copernicus.org/angeo-31-349-2013.pdf |
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| Zusammenfassung |
Substorm properties during different storm phases have been studied using an
automated recognition of substorm and storm phases in the auroral electrojet
(AL) and ring current (Dst) index data from 1995–2009. The large number of
events (about 500 storms and 15 000 substorms) provides statistically reliable
distributions, average behaviour and long time series of simple parameters,
such as durations and intensities. The phases of storms and substorms have
been examined independently. Substorm phases have been further combined to
single and multi-cycle events. The former consist of one growth, one
expansion and one recovery phase, while the latter include multiple expansion
and recovery phases after one growth phase.
Our findings show that most substorms take place during non-storm times, and
substorms during storm initial phases resemble isolated non-storm time
substorms. Both during storm initial phases and non-storm times, the substorm
growth phases may last longer than the other substorm phases. Substorm
recovery phase is typically the longest phase but its duration also varies
most. The longest substorm recovery phase duration was observed during
multi-cycle substorms. The longest substorm expansion and storm main phases
were found during the years close to the solar maximum. The shortest substorm
events (the shortest phase durations) are the single-cycle substorms. The
period of expansion onsets during multi-cycle substorms varied hugely for
events with a small number of expansion phases. For events with a larger
number of expansions, a clearer periodicity of about one hour (median value)
was suggested. |
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