  Recent observations have established that the magnetosphere is a system of
natural complexity. The co-existence of multi-scale structures such as auroral
arcs, turbulent convective flows, and scale-free distributions of energy
perturbations has lacked a unified explanation, although there is strong reason
to believe that they all stem from a common base of physics. In this paper we
show that a slow but turbulent convection leads to the formation of multi-scale
current filaments reminiscent of auroral arcs. The process involves an
interplay between random shuffling of field lines and dissipation of magnetic
energy on sub-MHD scales. As the filament system reaches a critical level of
complexity, local current disruption can trigger avalanches of energy release
of varying sizes, leading to scale-free distributions over energy perturbation,
power, and event duration. A long-term memory effect is observed whereby the
filament system replicates itself after each avalanche. The results support the
view that that the classical and inverse cascades operate simultaneously in the
magnetosphere. In the former, the high Reynolds-number plasma flow disintegrate
into turbulence through successive breakdowns; in the latter, the interactions
of small-scale flow eddies with the magnetic field can self-organize into
elongated current filaments and large-scale energy avalanches mimicking the
substorm.
