Influence of the interplanetary magnetic field on the variability of the mid-latitude F2-layer

The structure of the Interplanetary Magnetic Field (IMF) is responsible for an essential part of the variability of the ionospheric plasma as demonstrated by investigations of the influence of IMF sector boundary crossings as well as of ?Bz-changes (defined from satellite observations) to the maximal electron density of the F2-layer at different stations in mid-latitudes. It could be shown that negative Bz-values cause distinct negative ionospheric effects. Maximal effects were detected at high geomagnetic latitudes (ionospheric response decreases with decreasing latitude), high solar/geomagnetic activity, equinoxes and night-time conditions.