A physics based nonlinear dynamical model for the solar wind driven magnetosphere-ionosphere system

The predictive performance of a six-dimensional nonlinear dynamical model of the coupled magnetosphere-ionosphere system is compared to magnetospheric activity data. The model couples the basic energy components of the night-side magnetotail to the ionosphere by the region 1 currents. It predicts both the state of the geotail and the ionospheric westward electrojet index from the value of the solar wind speed. Except for the ionospheric dissipation, the system is both Kirchhoffian and Hamiltonian. This ensures that the solar wind input power is divided into physically realizable sub power components, a property not shared by signal processing filters. All the model parameters can be calculated analytically for different substorm scenarios. Agreement between the predicted and observed magnetospheric indices improves significantly when the system is coupled to particle simulations to produce realistic parameters for the model. Including the nonlinear increase of the ionospheric conductance with power deposited in the ionosphere is also essential. (C) 1998 Elsevier Science Ltd. All rights reserved.