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| Titel |
A 22-year cycle in the F layer ionization of the ionosphere |
| VerfasserIn |
E. Feichter, R. Leitinger |
| 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. 8 ; Nr. 15, no. 8, S.1015-1027 |
| Datensatznummer |
250012910
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| Publikation (Nr.) |
 copernicus.org/angeo-15-1015-1997.pdf |
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| Zusammenfassung |
| The double-sunspot-cycle variation in
terrestrial magnetic activity has been well known for about 30 years. In 1990 we
examined and compared the low-solar-activity (LSA) part of two consecutive
cycles and predicted from this database and from published results the existence
of a double-sunspot-cycle variation in total electron content (TEC) of the
ionosphere too. This is restricted to noontime when the semi-annual component is
well developed. Since 1995 we have had enough data for the statistical
processing for high-solar-activity (HSA) conditions of two successive solar
cycles. The results confirm the LSA findings. The annual variation of TEC shows
a change from an autumn maximum in cycle 21 to a spring maximum during the next
solar cycle. Similar to the aa indices for geomagnetic activity the TEC
data show a phase change in the 1-year component of the Fourier transform of the
annual variation. Additionally we found the same behaviour in the F-layer peak
electron density (Nmax) over four solar cycles. This indicates
that there exists a double-sunspot-cycle variation in the F-layer ionization
over Europe too. It is very likely coupled with the 22-year cycle in geomagnetic
activity. |
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