Magnetic Field Disturbance Induced by the Enhanced Suprathermal Ring Current in the Magnetosphere of Saturn

Saturn’s ring current, which regulates the global field configuration, exhibits dynamic variations due to the hot plasma injections. However, it’s difficult to quantify the transient magnetic field disturbance without local measurements on the surface of Saturn. Using a forward simulation method, we extracted the energetic ion distributions from energetic neutral atom (ENA) images, thereby estimating the energy content from the suprathermal ring current particles and corresponding magnetic field disturbance. We analyzed the ring current energy content and magnetic field perturbations during a dynamic event and show that suprathermal ring current energy tripled after injection, then rapidly decayed in the subsequent planetary rotation period. The magnetic field depression at the equator of planetary surface is ~21 nT after the injection, which is equivalent to a small geomagnetic storm in Earth's magnetosphere. The internal plasma sources and neutral gas environment result in the differences in ring current dynamics of Saturn and Earth, revealing the signatures of giant planet magnetosphere.