On relationships between horizontal velocity structure and thermal ion upwellings at high latitudes

Recent studies indicate that the vertical velocity of F region ion upwellin gs cannot be explained by frictional heating in the horizontal plane alone but requires additional energization sources. Processes involving velocity shear have recently been put forward as alternate mechanisms that can provi de the energization in regions of smaller convection speeds. Studies show t hat structured flows can also give rise to significant upwelling of ions by seeding plasma waves that can potentially cause ion heating while Joule he ating is relatively small. We provide a statistical analysis of the Dynamic s Explorer 2 vertical and horizontal ion drift measurements that show furth er evidence for the significance of plasma wave energization process in reg ions of varying levels of Joule heating.