Distinct solar wind pressure pulses producing convection twin-vortex systems in the ionosphere
Abstract. We provide conclusive observational evidence demonstrating that a solar wind pressure pulse produces a twin-vortex system of ionospheric currents, while a stepwise pressure increase/decrease creates a single vortex structure, at high-latitude ground magnetograms. Multi-satellite (Wind, Geotail, Interball, IMP 8 and GOES 8) and multi-instrument observations of plasma and magnetic field confirm with in situ measurements that solar wind inherent pressure pulses and stepwise variations strike on the Earth's magnetosphere in a global scale. The ground signatures are scrutinized in detail and the twin- or single-vortex current systems are studied using the IMAGE array stations. One more finding of this work is that a single vortex can produce monopolar and bipolar features, depending on the station position relative to the overhead travelling convection vortex (TCV). All of the above observational evidence confirms Glassmeier's (1992) prediction model that associates solar wind's steep changes of pressure with ionospheric TCVs.