The electromagnetic interaction between Jupiter and Io has been studied extensively since the 1964 discovery of Io-controlled decametric radio emissions (DAM) [Bigg, 1964]. A variety of mechanisms for the electromagnetic disturbance have been considered, including a unipolar induction electric field across Io producing a current loop closing in Jupiter’s ionosphere, the excitation of large-amplitude Alfvén waves, and the generation of electrostatic electric fields parallel to ambient magnetic field. Delamere et al. [2003] divided the Io-Jupiter interaction into three phases: an initial mass-loading interaction, acceleration of plasma in the wake of Io, and steady-state decoupling. The first two phases may induce an Alfvénic disturbance related to the bright emissions at Io’s magnetic footprint, whereas the latter phase sets up steady field-aligned currents in the downstream region of Io’s wake. By the analogy to the Earth’s auroral acceleration processes, Su et al. [2003] classified the Jupiter-Io coupling into three regions: an Alfvénic acceleration region, a quasi-steady planetward current region, and an anti-planetward current region. In this talk, I will review various theories and present our recent results of the electromagnetic coupling between the Jupiter’s ionosphere and the Io plasma torus.

Bigg, E. K., 1964, Nature, 203, 1008.
Delamere, P. A., Bagenal, F., Ergun, R. E., Su, Y.-J., 2003, J. Geophys. Res., 108(A6), 1241.
Su, Y.-J., Ergun, R. E., Bagenal, F., Delamere, P. A., 2003, J. Geophys. Res., 108(A2), 1094.