THE INFLUENCE OF HIGH-SPEED PLASMA STREAMS ON THE IONOSPHERIC PLASMA

As shown by statistical investigations, high speed plasma streams (HSP S) in the solar wind cause direct ionospheric effects in the D- and Es -layers at auroral and subauroral latitudes due to increasing precipit ation of high energetic particles as well as indirect effects in the F 2-region at high, middle and equatorial latitudes caused by auroral he ating processes. The ionospheric effects increase with the strength of the HSPS and are most pronounced for HSPS during IMF pro sectors (sec tors with negative B-z-component). Seasonal differences of the ionosph eric response to solar velocity changes are caused by the IMF influenc e (maximum effect at equinoxes) as well as internal atmospheric reason s (enhanced variability during winter).