SELF-ORGANIZED CRITICALITY: A NEW PARADIGM FOR THE MAGNETOTAIL DYNAMICS

The Earth's magnetosphere is an extended, complex system, usually far from equilibrium, that displays a very complex dynamics as a response to the solar wind input. Here, using the auroral electrojet index (AE) as a primary diagnostics of the energy flow released from the magnetosphere during the substorms, we investigated the existence of scaling laws for the "burst size" and "lifetime" distributions, and for the power spectral density (PSD). In particular, the "burst size" and "lifetime" distributions show a power-law dependence over many decades, characterized by scaling exponents near ≈ 3/2. Moreover, the PSD is characterized by a 1/f spectrum at lower frequencies. These results are discussed in the framework of a self-organized critical configuration for the Earth's magnetosphere and compared with similar results of numerical simulations on sandpile cellular automata.

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