Analysis of geomagnetic storms and substorms with the WINDMI model

A family of nonlinear dynamical models called WINDMI is developed to analyze the behaviour of geomagnetic storms and substorms. This set of plasma physics based descriptions of the interaction of the solar wind and the earth’s magnetosphere is aimed at understanding the key processes that influence geomagnetic activity, and consequently develop a reliable space weather prediction system. The global WINDMI-RC model is a system of eight nonlinear ordinary differential equations that describe the solar wind-magnetosphere-ionosphere coupling and the interaction of basic energy components in the nightside magnetosphere. The WINDMI-SR model is a spatially resolved version of the global WINDMI-RC model that decomposes the nightside magnetosphere into sections, with a system of differential equations attached to each section. The lowest order mode of the WINDMI-SR model corresponds to the behaviour of the WINDMI-RC model. The higher order modes describe electromagnetic pulses propagating along the geotail. The global model is computationally optimized using a genetic algorithm (GA) and used to analyze two large geomagnetic storm events. The GA optimization results show that the model is able to predict the storm time Dst index reliably and captures the timing and periodicity of the sawtooth signatures in the auroral Electrojet AL index reasonably well for both storm events. The spatially resolved model is used to study the propagation of electromagnetic pulses along the geotail and the response along the length of the nightside magnetosphere with changing solar wind activity.