Dissipation of solar wind energy in the Earth's upper atmosphere: The geomagnetic activity effect

This study deals with observed changes in the thermospheric temperature and density, which are known as the geomagnetic effect, a term derived from the fact that the intensity of the solar wind energy dissipation is nearly exclusively monitored by geomagnetic activity. Other terms used are thermospheric perturbation and thermospheric storm. This review attempts to summarize current knowledge from observations of this effect. The contents are as follows: 1) properties of the solar wind, including magnitude, dissipation mechanisms, spatial distribution, temporal variation, and the geomagnetic indices that monitor the strength and intensity variations of solar wind energy sources; 2) the quiet-time polar thermosphere; 3) thermospheric storms; 4) composition of the disturbance zone; 5) low-latitude effects of thermospheric storms; 6) systematic variations, including changes with magnetic activity, changes with local time, and changes with season; and 7) modelling of geomagnetic activity. An appendix discusses disturbance mechanisms and disturbance transport.