8.1.3 Plasmasphere

The plasmasphere is a region of cold dense plasma originating in the ionosphere and trapped by the Earth’s magnetic field. At low Lshells, the particles drift around the Earth on closed drift paths. This allows ions, escaping from the ionosphere, to accumulate to form this dense region. The boundary between closed and open drift paths is highly variable and the outer regions of the plasmasphere are continually being lost and refilled over a period of days. Typically, the plasmapause, the outer edge of the plasmasphere, lies at an Lshell (3.2.31) of 3 to 6, with a bulge in the dusk region of magnetic local time.

The Global Core Plasma Model (GCPM) [RN.8] is a widely used and well tested plasmasphere model and is recommended by the authors of IRI. It provides empirically derived plasma density as a function of geomagnetic conditions throughout the inner magnetosphere.