Transport of Mirror Mode Structures through Saturn’s Magnetopause Reconnection

Abstract Magnetopause reconnection plays a significant role in transferring plasma and energy from the solar wind to planetary magnetospheres. Using a Cassini measurement, we reported a magnetopause reconnection at Saturn, identified by the Hall magnetic field and the mixture of magnetosheath electron population and magnetosphere electron population near the X-line. Then, the mirror mode (MM) structures are identified both in the magnetosheath and the magnetosphere. Further analysis suggests that the MM structures were generated in the magnetosheath and traveled across the magnetopause. We infer that MM structures enter the magnetosphere through the magnetopause reconnection. This result provides a possible source for the MM structures in the magnetosphere. These observations and analyses also help to further understand the influence of Saturn’s magnetopause reconnection on the magnetosphere dynamics.