Global Nonlinear Model for the Evolution of the Dst Index

The NARMAX (Nonlinear Auto Regressive Moving Average model with eXogenous inputs) approach is used to analyse simultaneous measurements of the geomagnetic Dst Index and the merging rate of the IMF and the geomagnetic field VBs. A nonlinear discrete relation which describes the dynamics of the Dst index driven by VBs is derived directly from experimental measurements. This relation can be used to forecast the evolution of Dst index. Higher order spectral analysis of the identified model provides information about nonlinear coupling between the various spectral components.