Enhanced whistler-mode emissions: Signatures of interchange motion in the Io torus

During the Galileo inbound pass through the Io torus the plasma wave instrument detected intervals of enhanced whistler-mode emissions. Over two of these intervals in the inner torus (L < 6.5), for which energetic particle data is also available, the flux and pitch angle anisotropy of resonant electrons exhibited a simultaneous enhancement consistent with inward adiabatic transport from a source region in the outer torus. The enhanced electromagnetic emissions are interpreted as a modulation of cyclotron whistler-mode instability above the normal marginally stable state of the plasma. This suggests that the enhanced emissions are a sensitive indicator of rapid inward transport associated with interchange motions in the Io torus.