Coupling the plasma interaction at Io to Jupiter

Io's interaction with the jovian magnetosphere causes auroral and radio emissions. This interaction can not be modeled as either an Alfvén wave or a steady current loop alone. Given the Galileo measurement of low flow velocities in Io's wake, we argue that the interaction begins as an Alfvénic disturbance but as the disturbance is convected downstream it has time to evolve into a steady current loop. We associate high latitude phenomena with different phases of the interaction.