The Study of the Quasi‐Periodicity Observed on Plasma Density and Magnetic Field on Saturn's Magnetosphere: An Information Theory Approach

Abstract Saturn has been shown to exhibit periodicities ranging from minutes to days. A comprehensive understanding of the various physical drivers, their characteristic periodicities, and their potential interconnectedness is lacking, particularly in the context of overall mass (Saturn's net source/loss ∼50–100 kg/s) and magnetic flux (net = 0) transport. The paper focuses on periodicities ranging from Saturn's ubiquitous quasi‐period of 60 min (QP60) to less than the planetary rotation period (∼10.7 hr). For this study, we utilized a magnetohydrodynamics (MHD) simulation in conjunction with data from the Cassini spacecraft. We implemented the mutual information (MI) analysis on a source‐free Grid Agnostic MHD for Extended Research Applications (GAMERA) simulation to investigate the different quasi‐periodicities present in Saturn's magnetosphere and their implications for transport. We found a feedback relation between duskward‐propagating Kelvin‐Helmholtz (KH) surface waves forming at the subsolar magnetopause boundary and injection flows due to magnetotail reconnection. The KH surface waves have a natural period of roughly 1 hour; however, the feedback relationship occasionally amplifies the KH waves, leading to a 2–4 hr period.