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[1] Continuous samples of the ion drift are made near 800-km altitude from the DMSP satellite and compared with remote measurements of the F region neutral winds made from the ground at Eureka in the northern polar cap. These measurements are compared with each other and with variations in the interplanetary magnetic field and solar wind. Over a 6-day period, linear relationships between the north-south component of the IMF and the noon-midnight components of the ion and neutral drifts are used to determine the response times of the gas motions to changes in the solar wind driver. When the IMF is southward or weakly northward, the ion and neutral gas response begins almost immediately following a change in the solar wind driver. The time constant for the ion response is about 20 min, while for an F peak density of about 5 Â 10 5 cm À3 the neutral time constant is 75 min. While significant variability exists, the 55-min time difference between the response times is consistent with the neutral-ion collision time prevailing in the F region at the time and location of the measurements. In the quasi-equilibrium state, antisunward ion drifts in excess of 150 m s À1 drive the neutral gas antisunward with speeds about 60% of the ion drift.

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Upward vertical winds are observed in the polar cap F‐region over Eureka (80°N) during and following sustained polar auroras. This suggests that heating due to particle energy deposition in the F‐region is sufficient to generate upward flow. At such times there is a positive divergence in the horizontal winds, indicating that the upward flow is also outward over a >1000 km diameter across the central polar cap. The vertical winds, averaged over a 5‐winter period, also have a positive correlation with the horizontal divergences indicating the flow is generally large scale. Downward winds are seen to similarly correspond with negative divergences, and negative IMF Bz, suggesting they may be linked with activity at auroral latitudes. Vertical winds observed over Eureka at other times, appear to be oscillatory with 12‐hr and higher harmonic periods suggesting tidal activity. This preliminary conclusion will be tested by examining further winds and aeronomic data.

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