Observation of similar radio signatures at Saturn and Jupiter: Implications for the magnetospheric dynamics

Abstract

We report on radio signatures observed at Saturn by the Cassini RPWS experiment which are strikingly similar to the Jovian “energetic events” observed by Galileo. They consist of sudden intensifications of the auroral radio emission (SKR) followed by the detection of a periodic narrowband radiation which most likely originates from Saturn's plasma disk. About ten “events” have been observed in 2006, showing on average temporal scales ∼3 times longer than their Jovian counterparts. We analyze the conditions of generation and the visibility of the narrowband radiation and conclude that the Kronian “events” are most likely associated with plasma evacuation from the disk. These observations provide new insights on the role of internal energy releases in Saturn's magnetosphere, known from other observations to be mainly driven by the solar wind.