STRONG FLOW BURSTS IN THE NIGHTSIDE IONOSPHERE DURING EXTREMELY QUIETSOLAR-WIND CONDITIONS

Results of an HF radar study of convection during an extended quiet so lar wind interval on March 10 1997 are presented. After thirty hours d uring which the solar wind met the criteria for quiet conditions the H F radars at Sanae and Halley in Antarctica showed strong activity on t he night side. Flow bursts with velocities of more than 2000 m s(-1) c orresponding to electric fields exceeding 100 m V m(-1) were observed. These occurred quasi-periodically for almost two hours on the night-s ide with a repetition time of several minutes. It is concluded that th ey map to a region well inside the magnetotail. It is suggested that t hey are associated with sporadic energy release during reconfiguration of the tail magnetic field, and that this can occur even during and e xtended quiet solar wind period.