Multiscale Dynamics of the Magnetosphere

The dynamics of the magnetosphere is driven by the turbulent solar wind, and exhibits complex behavior with global, regional and local features. The global features are in general captured by the geomagnetic indices and the regional and local features are measured by spacecraft-based imagers and ground-based instruments. The global dynamical behavior has been studied extensively using nonlinear dynamical techniques. However the presence of a wide range of scales limits the ability of these techniques and a mean-field approach is used to obtain a deterministic model. This description is further improved by introducing a weighted averaging, with the weights determined by the distribution of sates in the reconstructed phase space. The multiscale aspects can not be described within a deterministic framework and a Bayesian approach is used to compute the conditional probabilities from the correlated solar wind - magnetosphere data. The regional features of the dynamics is studied using the mutual information functions computed from the magnetic field data from the high latitude magnetometer stations. The spreads in the average mutual information show a good correlation with the solar wind convective electric field and sudden changes in the dynamic pressure. The distribution of scales in the magnetosphere is studied using an extensive database. The distributions of the waiting times deviate significantly from a power law as well as stretched exponential distributions, and show a scaling with respect to the mean, indicating a limited role of long-term correlations in the magnetospheric dynamics.