SOLARNET Conference: The Many Scales of the Magnetic Sun

Observations of the quiet solar photosphere and chromosphere have revealed the ubiquitous presence of small-scale vortical motions. These features are tightly coupled to the surface magnetic field and extend in the vertical direction, potentially providing a channel for the transport of energy into the upper layers of the solar atmosphere.
We study the dynamics and statistical properties of small-scale vortices in realistic three-dimensional numerical simulations of the solar atmosphere obtained with the CO5BOLD code. Using the swirling strength criterion and its evolution equation, we find that numerous vortices are the plasma response to upwardly propagating torsional Alfvénic pulses that arise self-consistently from the convective and photospheric dynamics.
We have developed the SWIRL code, a new automatic vortex identification algorithm, to infer the statistical properties of the swirl population in the numerical simulations. Our analysis shows that vortices may be smaller, more numerous, and rotate faster than previously thought. Moreover, about 80% of the identified photospheric swirls correlate with twists in the magnetic field lines compatible with torsional Alfvénic pulses.