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 RS to as far as ∼60 RS from the planet (where 1 RS = 60268 km); the "arm" migrates an average of ∼3.4° in longitude for every RS 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. Copyright 2007 by the American Geophysical Union.