Saturn's periodic magnetic field perturbations caused by a rotating partial ring current

Abstract

We demonstrate that the periodic magnetic field perturbations as observed from Cassini are caused by the plasma pressure of the energetic (>2 keV) particle distributions that are periodically injected and subsequently drift around Saturn. Plasma pressures inferred from the Cassini Plasma Spectrometer (CAPS) (<2 keV) and the Magnetospheric Imaging Instrument (MIMI) (>2 keV) are used to compute the three-dimensional pressure-driven currents and their associated magnetic field perturbations. The distribution of the "hot" (>2 keV) plasma pressure is derived from Energetic Neutral Atom (ENA) images obtained by the Ion Neutral Camera (INCA) and in-situ spectral measurements. The radial profile of "cold" (<2 keV) plasma pressure is obtained from statistical studies and is assumed to be azimuthally symmetric. © 2010 by the American Geophysical Union.