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| Titel |
Some evidence of ground power enhancements at frequencies of global magnetospheric modes at low latitude |
| VerfasserIn |
P. Francia, U. Villante |
| 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 ; 15, no. 1 ; Nr. 15, no. 1, S.17-23 |
| Datensatznummer |
250012569
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| Publikation (Nr.) |
 copernicus.org/angeo-15-17-1997.pdf |
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| Zusammenfassung |
| A statistical analysis of the power spectra
of the geomagnetic field components H and D for periods ranging
between 3 min and 1 h was conducted at a low-latitude observatory (L'Aquila, L=1.6)
at the minimum and maximum of the solar cycle. For both components, during
daytime intervals, we found evidence of power enhancements at frequencies
predicted for global modes of the Earth\'s magnetosphere and occasionally
observed at auroral latitudes in the F-region drift velocities
(approximately at 1.3, 1.9, 2.6, and 3.4 mHz). Nighttime observations reveal a
relative low frequency H enhancement associated with the bay occurrence
together with a peak in the H/D power ratio which sharply emerges
at 1.2 mHz in the premidnight sector. The strong similarity between solar
minimum and maximum suggests that these modes can be considered permanent
magnetospheric features. A separate analysis on a two-month interval shows that
the observed spectral characteristics are amplified by conditions of
high-velocity solar wind. |
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