The Terrestrial Magnetosphere
A magnetosphere is shaped by the interaction between a planetary magnetic field and the solar wind. The magnetopause is a discontinuity separating both fields, forming a cavity in the solar wind. Since the solar wind is a supersonic flow, a standing shock wave, the bow shock, develops in front of the magnetopause. In the anti-sunward direction, the magnetosphere is stretched by the solar wind, forming the magnetotail. Inside the magnetosphere, different plasma regimes exist, dominated by ionospheric plasma in the plasmasphere, a highly variable mixture of ionospheric and heliospheric plasma in the geosphere, and by the solar wind plasma in the outer magnetosphere. These different regimes are coupled by fields and currents. Inside the plasmasphere energetic particles are trapped in the radiation belts. The inner magnetosphere can be approximated as a slightly distorted dipole field. It is coupled to the ionospheric current system, with energy in the form of particles and waves exchanged between both regimes. Both ionospheric currents and the ring current associated with the radiation belts modify the dipole field.
KeywordsSolar Wind Interplanetary Magnetic Field Geomagnetic Activity Plasma Sheet Solar Energetic Particle
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