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| Titel |
On the 18-day quasi-periodic oscillation in the ionosphere |
| VerfasserIn |
D. Altadill |
| 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 ; 14, no. 7 ; Nr. 14, no. 7, S.716-724 |
| Datensatznummer |
250012353
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| Publikation (Nr.) |
 copernicus.org/angeo-14-716-1996.pdf |
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| Zusammenfassung |
| The presence and persistence of an 18-day
quasi-periodic oscillation in the ionospheric electron density variations were
studied. The data of lower ionosphere (radio-wave absorption at equivalent
frequency near 1 MHz), middle and upper ionosphere (critical frequencies f0E
and f0F2) for the period 1970–1990 have been used in the
analysis. Also, solar and geomagnetic activity data (the sunspot numbers Rz and
solar radio flux F10.7 cm, and aN index respectively) were
used to compare the time variations of the ionospheric with the solar and
geomagnetic activity data. Periodogram, complex demodulation, auto- and
cross-correlation analysis have been used. It was found that 18-day
quasi-periodic oscillation exists and persists in the temporal variations of the
ionospheric parameters under study with high level of correlation and mean
period of 18–19 days. The time variation of the amplitude of the 18-day
quasi-periodic oscillation in the ionosphere seems to be modulated by the
long-term solar cycle variations. Such oscillations exist in some solar and
geomagnetic parameters and in the planetary wave activity of the middle
atmosphere. The high similarities in the amplitude modulation, long-term
amplitude variation, period range between the oscillation of investigated
parameters and the global activity of oscillation suggests a possible solar
influence on the 18-day quasi-periodic oscillation in the ionosphere. |
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