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Ann. Geophys., 16, 731-737, 1998
www.ann-geophys.net/16/731/1998/
© European Geosciences Union 1998
Fabry-Perot interferometer measurements of neutral winds and F2 layer variations at the magnetic equator
P. Vila1, D. Rees2, P. Merrien3, and E. Kone4
1CETP, 4 Avenue de Neptune, F-94107 St Maur des Fossés, France
2Center for Atmospheric and Space Studies, Utah State University, Logan, Utah 84322/4405, USA
3CSN Commissioner at the Korhogo station (Côte d'Ivoire) for 1996
4Département de Physique de l'Atmosphère, Université de Cocody, 22 BP 582 Abidjan, Côte d'Ivoire
Abstract. This letter presents some night-time
observations of neutral wind variations at F2 layer levels near the dip equator,
measured by the Fabry-Perot interferometer set up in 1994 at Korhogo (Ivory
Coast, geographic latitude 9.25°N, longitude 355°E, dip latitude –2.5°). Our
instrument uses the 630 nm (O1D) line to determine radial Doppler
velocities of the oxygen atoms between 200 and 400 km altitude. First results
for November 1994 to March 1995 reveal persistent eastward flows, and frequent
intervals of southward winds of larger than 50 ms–1 velocity.
Compared with the simultaneous ionospheric patterns deduced from the three West
African equatorial ionosondes at Korhogo, Ouagadougou (Burkina-Faso, dip
latitude +1.5°) and Dakar (Sénégal, dip latitude +5°), they illustrate
various impacts of the thermospheric winds on F2 layer density: (1) on the
mesoscale evolution (a few 103 km and a few 100 minutes scales) and
(2) on local fluctuations (hundreds of km and tens of minutes characteristic
times). We report on these fluctuations and discuss the opportunity to improve
the time-resolution of the Fabry-Perot interferometer at Korhogo.
Key words. Ionosphere (Equatorial ionosphere;
Ionosphere-atmosphere interaction) · Meteorology and Atmospheric Dynamics
(General circulation)
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