Geomagnetic transport in the solar wind driven nightside magnetosphere–ionosphere system

A spatially resolved nonlinear dynamical model of the solar wind driven geomagnetic tail plasma is developed for the purpose of space weather predictions. The model represents the fluctuating electromagnetic fields and high pressure central plasma sheet by a large number (2N&200) of semiglobal coupled current loops ranging from the near-Earth geosynchronous orbit position for substorm dynamics to deep in the geotail. There is a spectrum of dynamical frequencies ranging from 1 h periods to 1 min and shorter periods. The low-frequency modes are global and lead to the dynamics of the low-dimensional (d56) WINDMI model. The high-frequency dynamics are nonlinear compressional-rarefraction waves propagating up and down the geotail. The localized pulses start from sites of local reconnection set off either by the tearing mode unloading trigger or by localized solar wind disturbances acting on the nightside magnetopause. Larger unloading events lead to nonlinear steepening of the compressional pulsations which act to trigger secondary convection events under certain conditions. © 2002 American Institute of Physics. @DOI: 10.1063/1.1499119#