OBSERVATIONS OF ACOUSTIC-GRAVITY WAVES IN THE THERMOSPHERE FOLLOWING SPACE-SHUTTLE ASCENTS

Using an ionospheric Doppler sounder al Havelock, North Carolina, we observed upper atmospheric waves generated by three ascents of the Space Shuttle during 1990-1991. The exhaust plume's initial explosion and subsequent buoyant rise apparently launch acoustic and buoyancy waves, respectively. The bouyancy waves observed close (< 150 km) to the flight path are shorter period (200 s) than the Brunt-Vaisaila period. This may be due to wind-generated Doppler shifts, or alternatively to the waves being ducted on the thermocline.