Further observations of the thermospheric vertical wind at the auroral oval/polar cap boundary

The size of the zenith wind events (up to ∼120 m s−1) seen in our observations at Mawson are comparable with the amplitude of oscillations seen in gravity waves propagating at ∼300 km altitude over the polar cap from the nightside to the dayside, detected by Johnson et al. (1995) from Dynamics Explorer 2 observations. This similarity and the fact that we see the upward winds at the night-time auroral oval/polar cap boundary suggest that the origin of the upward winds may be intrinsically linked to the processes that generate these gravity waves.