The solar{wind driven magnetosphere{ionosphere as a complex dynamical system

The solar{wind driven magnetosphere{ionosphere system is a classic example of a complex dynamical system (CDS). The de ning properties of a CDS are (1) sensitivity to initial conditions; (2) multiple space{time scales; (3) bifurcation sequences with hysteresis in transitions between attractors; and (4) noncompositionality. Noncompositionality means that the behavior of the system as a whole is di erent from the dynamics of its subcomponents taken with passive or no couplings. In particular the dynamics of the geomagnetic tail plasma depends on its coupling to the dissipative ionospheric plasma and on the nature of the solar wind driving electric eld over a suitably long (many hours) previous time interval. These complex dynamical system features are shown here in detail using the known WINDMI model for the solar wind driven magnetosphere{ionosphere (MI) system. Numerous features in the bifurcation sequence are identi ed with known substorm and storm characteristics.