Energetic Electron Patterns in the New SLS5 Longitude System

Abstract

Energetic electron (110-300 keV) fluxes collected during the entire 13-year Cassini mission are organized in the new Saturn longitude system (SLS5). This system is based on Saturn radio emissions, varies slowly in time and has a north and a south branch. When the fluxes are organized in SLS5 longitudes and magnetodisk coordinates, they display an m=1 wave pattern that is quasi-linear in longitude-range maps. These spiral patterns are easily recognized in energetic electrons and have positive slopes a few degrees of longitude per R_S (1 R_S =60,268 km), similar to that observed in both particles and magnetic fields earlier in the mission. The patterns are most prominent at elevations +2 R_S (SLS5 north) or -2 R_S (SLS5 south) relative to the magnetodisk center. The results indicate the persistence of this pattern for essentially half a Saturnian year, suggesting that this pattern is a quasi-permanent feature of the magnetosphere, much the same as its plasma sheet or magnetopause.