STORM-TIME PENETRATION TO LOW LATITUDES OF MAGNETOSPHERIC-IONOSPHERICCONVECTION AND CONVECTION-DRIVEN THERMOSPHERIC WINDS

From DE-2 satellite measurements during two magnetic storms, we show t hat (i) the magnetospheric convection-driven east-west ion flows of hi gh velocities (1400 m/s) penetrate to magnetic latitudes as low as 30 degrees, with larger velocities (2000-3000 m/s) appearing at 45 degree s 50 degrees latitudes, and (ii) high velocities (300-640 m/s) thermos pheric winds appear in association with the : above ion flows. The sim ilarity of the latitude structures and time evolutions of the ion and neutral motions indicates that the zonal winds are driven by ma,magnet ospheric-ionospheric convection through ion drag. These velocities of the convection-driven ion flows and winds at such low latitudes are mu ch larger than those reported from observations or predicted by curren t models.