Response of the topside ionosphere to high-speed solar wind streams

Abstract

[1] During an 80 d period in 2008 the ionosphere was driven very coherently by periodic high-speed solar wind streams. An examination of the high-latitude ionospheric dynamics during this period indicates that changes in the polar cap potential drop from 20 to 60 kV induce global changes in the dynamics, composition, and temperature of the topside ionosphere. These changes in the potential are small compared to those usually seen during times of higher solar activity. Changes in the polar cap potential produce significant increases in the frictional heating of the ions and neutral gas associated with antisunward flows in the polar cap. These increases are accompanied by expansions in the latitude extent over which the return sunward flows exist. Thus, no significant increase in the magnitude of the flows is seen in this region, and the plasma in the auroral zone remains relatively cool compared to that seen in the polar cap. Associated with changes in the high-latitude convection are changes in the topside ion temperature of 100 to 150 K that extend from the auroral zone itself to latitudes as low as 20°.