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| Titel |
Statistical study of the night-time F-layer dynamics at the magnetic equator in West Africa during the solar minimum period 1995–1997 |
| VerfasserIn |
K. S. Tanoh, B. J.-P. Adohi, I. S. Coulibaly, C. Amory-Mazaudier, A. T. Kobea, P. Assamoi |
| 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 ; 33, no. 1 ; Nr. 33, no. 1 (2015-01-30), S.143-157 |
| Datensatznummer |
250121158
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| Publikation (Nr.) |
 copernicus.org/angeo-33-143-2015.pdf |
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| Zusammenfassung |
| In this paper, we report on the night-time equatorial F-layer height
behaviour at Korhogo (9.2° N, 5° W; 2.4° S
dip lat), Ivory Coast, in the West African sector during the solar minimum
period 1995–1997. The data were collected from quarter-hourly ionograms of
an Ionospheric Prediction Service (IPS) 42-type vertical sounder. The main focus of this work was to study
the seasonal changes in the F-layer height and to clarify the equinox
transition process recently evidenced at Korhogo during 1995, the year of
declining solar flux activity. The F-layer height was found to vary strongly
with time, with up to three main phases. The night-to-night variability of
these morphological phases was then analysed. The early post-sunset slow
rise, commonly associated with rapid chemical recombination processes in the
bottom part of the F layer, remained featureless and was observed regardless of the date. By contrast, the following event, either presented like the
post-sunset height peak associated with the evening E × B drift, or was delayed
to the midnight sector, thus involving another mechanism. The statistical
analysis of the occurrence of these events throughout the solar minimum
period 1995–1997 revealed two main F-layer height patterns, each
characteristic of a specific season. The one with the post-sunset height
peak was associated with the northern winter period, whereas the other, with the
midnight height peak, characterized the northern summer period. The
transition process from one pattern to the other took place during the
equinox periods and was found to last only a few weeks. We discuss these
results in the light of earlier works. |
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