Dual periodicities in energetic electrons at Saturn

Abstract

The fluxes of energetic electrons (110-365 keV) in Saturn's magnetosphere were subjected to Lomb periodogram analyses for 1677 days from late 2004 to the middle of 2009. The electrons generally exhibited strong periodicities at 10.82 hours and 10.60 hours for much of the ∼4.6 year interval. The longer period was generally present all the time, while the shorter period became prominent during the last ∼600 days of the interval. The 10.8-hour signal appeared strongly in observations made north of the equator and weakly in the south, while the 10.6-hour signal appeared only for northern observations. The dual periodicity in the electrons is similar to that recently discovered in the Saturn kilometric radiation. Periods in the 10.6 to 10.8 hour range are similar to the sun-referenced periods of neutral winds measured in Saturn's polar atmospheres. Copyright 2009 by the American Geophysical Union.