A revised forest-fire cellular automaton for the nonlinear dynamics of the Earth's magnetotail

Recent observations and numerical simulations seem to suggest that the Earth's magnetotail plasma could exist in a near-criticality configuration, and that many features of the magnetospheric, response to solar wind changes could be described by avalanche models displaying self-organized criticality, Further evidences of this near-criticality dynamics have been found analyzing the statistical features of the auroral electrojet (AE) index. Here, we present a cellular automaton, based on a revised version of the well-known forest-fire model, for the nonlinear dynamics of the Earth's magnetotail. This simple model, chaotically driven using a 1-d coupled map, is able to capture many of the statistical features of the magnetospheric response to solar wind changes. The results, compared with previous analyses of the AE-index features, are discussed in the framework of a near-criticality dynamics of the magnetospheric tail plasma. (C) 2001 Elsevier Science Ltd. All rights reserved.