The dynamics of small-scale magnetic fields modulated by the solar cycle

In addition to sunspots, which represent the most easily visualized manifestation of solar magnetism, cutting-edge observations of thesolar atmosphere have uncovered a plethora of magnetic flux tubes, down to the resolving power of modern high-resolution telescopes(a few tens of km), revealing how the Sun is a fully magnetized star. These magnetic elements are advected and buffeted by ambientplasma flows and turbulent convection, resulting in perturbations of the flux tubes that make them natural conduits for channelingwave energy into the upper layers of the Sun’s atmosphere and significantly contributing to the acceleration of the solar wind. Today,data acquired by the Helioseismic and Magnetic Imager (HMI) onboard NASA’s Solar Dynamics Observatory (SDO), have made itpossible to study the dynamics of small-scale magnetic fields over long timescales. Here, for the first time, we present the discoveryof a modulation in the dynamical behavior of small-scale magnetic concentrations in the photosphere over temporal scales consistentwith the solar activity cycle (i.e., 11 years), which has only been made possible by the long observing lifetime of the SDO/HMIspacecraft. Furthermore, a temporal varying polarization of their perturbations is also found on similar timescales. This demonstrateshow the small-scale dynamics of magnetic fields are also affected by the global dynamo. These discoveries were realized throughautomated tracking of magnetic fields in the solar photosphere across 11 continuous years, resulting in the most extended statisticalanalyses of its kind so far, with more than 31 million magnetic concentrations examined.