Evidence for spiral pattern in Saturn's magnetosphere using the new SKR longitudes

Abstract

The periodicities in electrons observed in Saturn's magnetosphere are examined using the new longitude system based on a drifting signal of Saturn kilometric radiation (SKR). When averaged into longitude and range bins over 50-day time periods, 28-48 keV electron intensities clearly evidence patterns that peak at successively increasing longitudes with increasing radial distance from Saturn. That is, the electrons form a spiral pattern in the quasi-corotational frame of SKR longitude. The spiral has only one ``arm'' that extends from ~10 R<sub>S</sub> to as far as ~60 R<sub>S</sub> from the planet (where 1 R<sub>S</sub> = 60268 km); the ``arm'' migrates an average of ~3.4° in longitude for every R_S of radial distance. The spiral does not remain fixed in SKR longitude, but changes its relative position on time scales of ~50 days. The ``base'' of one spiral appears connected with a postulated convection outflow at ~330° longitude.