The dynamics of storms and substorms with the WINDMI model

Abstract

WINDMI is a physics based eight-dimensional state-space model that simulates the flow of energy between the dominant global energy components in the nightside magnetosphere. The model is intrinsically three-dimensional in configuration space, and uses the basic geometry of the Tsyganenko magnetic field model to define the physical quantities. The dynamical equations satisfy the laws of energy and charge conservation for the network of branches and nodes formed by the topology of the ambient magnetic field. The model includes energy coupled by injected plasma from the plasma sheet across the Alfvén layer into the ring current. The power input into the model is the electromotive plasma dynamo derived from solar wind parameters. The output of the model is the westward Auroral Electrojet current and the energy stored in the Earth’s ring current. The prediction of the model is compared to the geomagnetic AL and D st indices. These indices measure fluctuations of the earth’s magnetic field at its surface. The model parameters have been optimized using a genetic algorithm with the Average Relative Variance (ARV) as a performance metric for five of the seven designated Geospace Environment (GEM) storms. Results for the October 3–7 2000 GEM storm and the October 20–22 2001 GEM storm are given here. The optimized models appear to give a reliable method of making predictions from the solar wind for a range of auroral and ring current activity.