Abstract
The high-latitude ionosphere is the main region for coupling from the outer regions of the magnetosphere. The distribution of electric fields and currents reflects the various boundaries between magnetospheric regions and responds immediately to variations in these boundaries caused by changes in the solar wind. During the recent years our knowledge of these variations and their coupling to the ionosphere has increased considerably due to the establishments of ground-based facilities with good temporal and spatial resolution like incoherent and coherent scatter radars, magnetometer arrays and all-sky imaging instruments. Nevertheless, the physical models which are available, are still too limited to explain the observations.
