Neutral winds above 200 km at high latitudes

Electrically neutral, luminous clouds are a by‐product of chemical releases conducted to create barium ion clouds for the measurement of electric fields. Wind measurements provided by the motions of these clouds are particularly valuable in that the motions can be directly compared with convective ion drift motions to test the importance of ion drag forces. Motion from multiple releases between 200 and 300 km from 15 rockets launched from four high‐latitude locations is analyzed in this paper. The observations in the evening and midnight hours at magnetic latitudes of ≥65° strongly suggest that in these regions ion drag is the dominant force in driving neutral winds between 200 and 300 km. This conclusion is based on both the agreement between ion and neutral drift directions and the fact that there are distinct changes in the wind associated with ( a ) the reversal in east‐west ion drift at the Harang discontinuity, and ( b ) the transition from auroral belt sunward ion drift and polar cap antisolar ion drift. In the morning sector it is evident that neutral wind observations cannot be directly interpreted in terms of ion drag; other factors must be considered, such as inertial effects from ion drag, a lack of sufficient ionization for strong coupling of ion neutral motions, and wind forces other than ion drag forces.