Geospace storm dynamics

Geospace storms, also known as space or magnetic storms, interconnect the Sun and interplanetary space with the terrestrial magnetosphere, ionosphere, and atmosphere — and often even the surface of the Earth — in a uniquely global and synergistic manner. Energy from the Sun drives a continuous interaction of these distinct but coupled regions. Geospace storms have traditionally been called geomagnetic storms, because of the defining feature of global geomagnetic field disturbances that they induce. However, observations over four decades of space-borne instrumentation have shown that storms involve more than just variations in the geomagnetic field: they involve acceleration of charged particles in the magnetosphere, modification of the electrodynamic properties of the ionosphere, heating of the upper atmosphere, and creation of geomagnetically induced currents on the ground. This chapter attempts a synoptic discourse of geospace magnetic storm history, the classical perception of magnetic storm dynamics, and deviations from long-time accepted paradigms. In particular, we review in some detail one of the critical issues of storm dynamics, namely the storm-substorm relationship.