Responses of the mesospheric wind at high latitudes to the April 2002 space storm

[1] An intense space storm occurred on 17–20 April, 2002. The effects of this storm on the mesospheric wind system were observed by two meteor wind radars at Andenes (69N, 16E) and Esrange (68N, 21E). At those locations, neutral winds showed a pattern similar to the ion convection pattern on 17 April for several hours at altitudes of 94–97 km. It is the first time that this kind of wind pattern is detected at such low altitudes. In contrast, winds by a medium frequency radar at Poker Flat (65N, 213E) showed no obvious storm effect, reflecting different responses of the dayside atmosphere and the nightside atmosphere. The ion convection wind pattern at Andenes and Esrange only appeared on the first day of the storm. We hypothesize that this behaviour may be related to a short-lived but prominent electron density enhancement in the local thermosphere on the same day observed by an incoherent scatter radar at Svalbard (78N, 16E).