Statistical Properties of Magnetic Activity in the Solar Corona


The long-time statistical behaviour of a two-dimensional section of a coronal loop subject to random magnetic forcing is presented. The highly intermittent nature of dissipation is revealed by means of magnetohydrodynamic (MHD) turbulence numerical simulations. Even with a moderate magnetic Reynolds number, intermittency is clearly present both in space and time. The response of the loop to the random forcing, as described either by the time series of the average and maximum energy dissipation or its spatial distribution at a given time, displays a gaussian noise component which may be subtracted to define discrete dissipative events. Distribution functions of both maximum and average current dissipation, of total energy content, of peak activity and of duration of such events are all shown to display robust scaling laws, with scaling indices delta which vary from delta = -1.3 to delta = -2.8 for the temporal distribution functions, while delta = -2.6 for the overall spatial distribution of dissipative events.

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