Magnetospheric dynamics from a low-dimensional nonlinear dynamics model

A physics based model for the coupled solar WIND-Magnetosphere-Ionosphere s ystem (WINDMI) is described. The model is based on truncated descriptions o f the collisionless microscopic energy transfer processes occurring in the quasineutral layer, and includes a thermal flux limit neglected in the Magn etohydrodynamic (MHD) closure of the moment equations. All dynamically rele vant parameters of the model can be computed analytically. The system is bo th Kirchhoffian and Hamiltonian, ensuring that the power input from the sol ar wind is divided into physically realizable energy sub-components, a prop erty not shared by data-based filters. The model provides a consistent math ematical formalism in which different models of the solar wind driver, iono spheric dissipation, global field configuration, and substorm trigger mecha nism can be inserted, and the coupling between the different parts of the s ystem investigated. (C) 1999 American Institute of Physics. [S1070-664X(99) 97005-2].