The Upper Atmosphere's Response to the Magnetosphere
The upper atmosphere responds strongly to the highly variable magnetosphere, which is the dominant source of high-latitude ionospheric electrodynamics and energetic particle precipitation. Electromagnetic stresses and energy deposition drive thermospheric winds and variations in neutral density and composition, not only at high latitudes, but also on a global scale. The ionosphere is affected by the thermospheric changes, as well as by plasma convection and energetic-particle ionization. The electrodynamic coupling between the upper atmosphere and the magnetosphere is mutual, and is influenced by changes in ionospheric conductivity and thermospheric winds. We need accurate knowledge of the magnetospheric energy and momentum inputs to the upper atmosphere in order to model and predict the system state. This talk surveys our current understanding of the upper-atmospheric response to the magnetosphere, and identifies some future research areas.