Statistical Properties of Magnetic Activity in the Solar Corona
Abstract
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.
Subject headings: MHD - Sun: corona - Sun: flares - Sun: magnetic fields - turbulence
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