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| Titel |
West African equatorial ionospheric parameters climatology based on Ouagadougou ionosonde station data from June 1966 to February 1998 |
| VerfasserIn |
F. Ouattara, C. Amory-Mazaudier, R. Fleury, P. Lassudrie Duchesne, P. Vila, M. Petitdidier |
| 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 ; 27, no. 6 ; Nr. 27, no. 6 (2009-06-23), S.2503-2514 |
| Datensatznummer |
250016563
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| Publikation (Nr.) |
 copernicus.org/angeo-27-2503-2009.pdf |
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| Zusammenfassung |
| This study is the first which gives the climatology of West African
equatorial ionosphere by using Ouagadougou station through three solar
cycles. It has permitted to show the complete morphology of ionosphere
parameters by analyzing yearly variation, solar cycle and geomagnetic
activity, seasonal evolution and diurnal development. This work shows that
almost all ionospheric parameters have 11-year solar cycle evolution.
Seasonal variation shows that only foF2 exhibits annual, winter and
semiannual anomaly. foF2 seasonal variation has permitted us to identify and
characterize solar events effects on F2 layer in this area. In fact (1)
during quiet geomagnetic condition foF2 presents winter and semiannual
anomalies asymmetric peaks in March/April and October. (2) The absence of
winter anomaly and the presence of equinoctial peaks are the most visible
effects of fluctuating activity in foF2 seasonal time profiles. (3) Solar
wind shock activity does not modify the profile of foF2 but increases
ionization. (4) The absence of asymmetry peaks, the location of the peaks in
March and October and the increase of ionization characterize recurrent
storm activity. F1 layers shows increasing trend from cycle 20 to cycle
21. Moreover, E layer parameters seasonal variations exhibit
complex structure. It seems impossible to detect fluctuating activity effect
in E layer parameters seasonal variations but shock activity and wind stream
activity act to decrease E layer ionization. It can be seen from Es layer
parameters seasonal variations that wind stream activity effect is fairly
independent of solar cycle. E and Es layers critical frequencies and virtual
heights diurnal variations let us see the effects of the greenhouse gases in
these layers. |
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