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| Titel |
The effect of magnetic substorms on near-ground atmospheric current |
| VerfasserIn |
E. Belova, S. Kirkwood  , H. Tammet |
| 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. 12 ; Nr. 18, no. 12, S.1623-1629 |
| Datensatznummer |
250014106
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| Publikation (Nr.) |
 copernicus.org/angeo-18-1623-2000.pdf |
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| Zusammenfassung |
Ionosphere-magnetosphere disturbances at high
latitudes, e.g. magnetic substorms, are accompanied by energetic particle
precipitation and strong variations of the ionospheric electric fields and
currents. These might reasonably be expected to modify the local atmospheric
electric circuit. We have analysed air-earth vertical currents (AECs) measured
by a long wire antenna at Esrange, northern Sweden during 35 geomagnetic
substorms. Using superposed epoch analysis we compare the air-earth current
variations during the 3 h before and after the time of the magnetic X-component
minimum with those for corresponding local times on 35 days without substorms.
After elimination of the average daily variation we can conclude that the effect
of substorms on AEC is small but distinguishable. It is speculated that the AEC
increases observed during about 2 h prior to the geomagnetic X-component
minimum, are due to enhancement of the ionospheric electric field. During the
subsequent 2 h of the substorm recovery phase, the difference between "substorm"
and "quiet" atmospheric currents decreases. The amplitude of this
"substorm" variation of AEC is estimated to be less than 50% of the
amplitude of the diurnal variation in AEC during the same time interval.
The statistical significance of this result was confirmed using the Van der
Waerden X-test. This method was further used to show that the average air-earth
current and its fluctuations increase during late expansion and early recovery
phases of substorms.
Key words: Ionosphere (electric fields and currents) ·
Magnetospheric physics (storms and substorms) · Meteorology and atmospheric
dynamics (atmospheric electricity) |
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