Storm-time penetration to low latitudes of magnetospheric-ionospheric convection and convection-driven thermospheric winds

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