Authors: Oana Vesa (Stanford University); Juie Shetye (New Mexico State University); Erwin Verwichte (Centre for Fusion, Space and Astrophysics, University of Warwick)

Chromospheric swirls (or magnetic tornadoes) are small-scale vortices observed in the quiet solar chromosphere that are thought to play a vital role in the heating and dynamics across the solar atmosphere. We present the first observations of chromospheric swirls with the Dunn Solar Telescope’s Hydrogen-alpha Rapid Dynamics camera and Rapid Oscillations in the Solar Atmosphere imaging instruments to characterize their morphology, temporal evolution, and dynamics. We track the evolution and dynamics of 34 chromospheric swirls and their footpoints, or bright points (BPs), from the low photosphere to the middle chromosphere. We use methods such as image segmentation, Fourier and spectral analysis, and local correlation tracking to investigate swirl-BP dynamics.Our observations show that swirls have an average lifetime of 7.9\,$\pm$\,5\,min and average diameter of 3.6\,$\pm$\,1\,Mm. A positive correlation between lifetimes and diameters found suggests that smaller swirls live shorter lifetimes. We also find that 76$\%$ are associated with a compact BP. Most of the BPs appear after the visible formation of a swirl, in the range of 12\,s to 9\,min. We detect a strong link between the global motions of BPs and their co-spatial swirl. Analysis of rotational dynamics shows that swirls have a mean angular speed of 0.04\,rad\,s$^{-1}$, phase speed of 17.7\,km\,s$^{-1}$, and period of 180\,s. We also capture the formation of a large swirl with clearly defined spiral arms caused by the interaction of its BP with a large photospheric vortex flow. We observe the BP being dragged toward the center of the photospheric vortex flow, after which the swirl starts forming. Within this convective vortex motion, the BP undergoes visual changes in orientation and appearance from circular to elongated that match the swirl’s evolution in the middle chromosphere. We find an out-of-phase behavior between the angular velocity of the BP and swirl with a phase delay of -57.5\,s. Our results support that swirls are magnetically driven structures with a footpoint in the form of BPs on the photosphere, whose motions drive the overlying motions of the swirl.