ULF waves in Ganymede's upstream magnetosphere

Abstract. Ganymede's mini-magnetosphere, embedded in Jupiter's larger one, sustains ULF (ultra-low frequency) waves that are analyzed here using data from two Galileo flybys that penetrate deeply into the upstream closed field line region. The magnetometer data are used to identify field line resonances, magnetopause waves and ion cyclotron waves. The plasma densities that are inferred from the interpretation of these waves are compared with the observations made by other plasma and wave experiments on Galileo and with numerical and theoretical models of Ganymede's magnetosphere.