Temporal and Spatial Variations of Mid-Latitude Ionospheric Trough During a Geomagnetic Storm Based on Global GNSS-TEC and Arase Satellite Observations

Summary form only. The Earth's plasmasphere is the vast ‘doughnut’ shaped dense plasma region of the magnetosphere that is filled with cold ions and electrons of ionospheric origin. The plasmaspheric plasma density shows an abrupt drop by a factor of 5 or more around 4–6 Re (Re: Earth's radius). The boundary has been called ‘plasmapause’. Since the plasmaspheric cold plasma controls generation of plasma waves, their propagation features, and particle acceleration via wave-particle interaction, detailed investigation of the temporal and spatial variations of the plasmasphere and plasmapause location during a geomagnetic storm is important for understanding a change in plasma wave environments in the inner magnetosphere.