ULF wave observations in Jupiterʹs magnetosphere Original Research Article

In previous work we have examined magnetometer data from the Ulysses Jupiter flyby, and in particular middle magnetosphere observations in the vicinity of the magnetodisk. Waves transverse to the background magnetic field were found in the heavy ion gyrofrequency regime, a signature of Ion Cyclotron (IC) waves. We examined the dayside and high latitude duskside high resolution 1 sec data. Wave signatures were observed on several occasions both close to the magnetic equator and at some distance from it. Lower mass ion signatures were observed further away from the planet and the heaviest mass ion signatures appear closer to the Io torus although still at some distance from it. IC waves and their propagation properties can be used as a diagnostic of the particle species in a multicomponent plasma. Here we present polarization analysis of a portion of the Ulysses magnetometer wave observations in the middle Jovian magnetosphere during the inbound pass and close to plasma sheet approaches. The analysis show transverse waves in the heavy ion gyrofrequency regime with left-hand polarization in some cases and right-hand polarisation in others. We discuss these results in terms of polarization reversal properties of ULF waves propagating in a multicomponent plasma.