Statistical study of the night-time F-layer dynamics at the magnetic equator in West Africa during the solar minimum period 1995–1997
| Autor: | P. Assamoi, Christine Amory-Mazaudier, A. T. Kobea, B. J.-P. Adohi, I. S. Coulibaly, K. S. Tanoh |
|---|---|
| Přispěvatelé: | Laboratoire de Physique de l'Atmosphère, Université de Cocody, 22 BP 582 Abidjan 22, Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Abdus Salam International Centre for Theoretical Physics [Trieste] (ICTP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Solar minimum
Atmospheric Science Evening Meteorology [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] lcsh:QC801-809 Magnetic dip [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Geology Astronomy and Astrophysics Equinox Atmospheric sciences lcsh:QC1-999 West africa lcsh:Geophysics. Cosmic physics Space and Planetary Science Midnight Earth and Planetary Sciences (miscellaneous) Period (geology) lcsh:Q Ionosphere lcsh:Science lcsh:Physics |
| Zdroj: | Annales Geophysicae Annales Geophysicae, European Geosciences Union, 2015, 33 (1), pp.143-157. ⟨10.5194/angeo-33-143-2015⟩ Annales Geophysicae, Vol 33, Pp 143-157 (2015) Annales Geophysicae, 2015, 33 (1), pp.143-157. ⟨10.5194/angeo-33-143-2015⟩ |
| ISSN: | 0992-7689 1432-0576 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|