FABRY-PEROT-INTERFEROMETER MEASUREMENTS OF NEUTRAL WINDS AND F2 LAYERVARIATIONS AT THE MAGNETIC EQUATOR

This letter presents some night-time observations of neutral wind vari ations at F2 layer levels near the dip equator, measured by the Fabry- Perot interferometer set up in 1994 at Korhogo (Ivory Coast, geographi c latitude 9.25 degrees N, longitude 355 degrees E, dip latitude -2.5 degrees). Our instrument uses the 630 nm ((OD)-D-1) line to determine radial Doppler velocities of the oxygen atoms between 200 and 400 km a ltitude. First results for November 1994 to March 1995 reveal persiste nt eastward flows, and frequent intervals of southward winds of larger than 50 ms(-1) velocity. Compared with the simultaneous ionospheric p atterns deduced from the three West African equatorial ionosondes at K orhogo Ouagadougou (Burkina-Faso, dip latitude + 1.5 degrees) and Daka r (Senegal, dip latitude + 5 degrees), they illustrate various impacts of the thermospheric winds on F2 layer density: (1) on the mesoscale evolution (a few 10(3) km and a few 100 minutes scales) and (2) on loc al fluctuations (hundreds of km and tens of minutes characteristic tim es). We report on these fluctuations and discuss the opportunity to im prove the time-resolution of the Fabry-Perot interferometer at Korhogo .