Observation of Flux Modulations in SKR and Low Frequency Waves, Relations with Other Measurements and Possible Implications on the Magnetospheric Activity.

Pronounced modulations of the flux of low frequency waves (whistler mode around 50 Hz) have been observed (RPWS experiment) on day 181 and 182 as Cassini was above the plasmasheet at a distance of 25-15 Rs from Saturn. They present a typical periodicity of 50- 90 minutes. During the same time interval, the fluxes of the auroral radio emission (SKR) and of the energetic particles (INCA experiment) present similar modulations. The magnetic field (MAG instrument) also fluctuates, suggesting that global scale magnetospheric oscillations are observed (analogue to pi2/pc5 at Earth ?). Considering other time intervals, we show that similar modulations are often detected in the flux of SKR with periodicity of several tens of minutes. The phenomena would thus be frequent, perhaps systematic, suggesting that these oscillations are an important element of the activity of Saturn's magnetosphere.