Some Problems of Identifying Types of Large-Scale Solar Wind and Their Role in the Physics of the Magnetosphere: 4. The “Lost Driver”

Abstract

One perturbed type of solar wind and magnetospheric disturbance drivers is the compression region in front of fast ICMEs—the Sheath region. In front of this region, an interplanetary shock is observed in approximately half of cases. However, the parameters and their time profiles in these two types of the Sheath region differ comparatively little. Therefore, the Sheath region without a shock is as geoeffective as the Sheath region with a shock: the Sheath region in the first case generated almost 10% of magnetic storms with a minimum Dst < –50 nT of all the magnetic storms for 1976–2017 with identified interplanetary drivers. Many authors do not analyze this driver (for this reason, we call it the “lost driver”); therefore, their studies contain incorrect conclusions on solar–terrestrial physics.