ON ZONAL WIND DRIVEN CURRENT SYSTEMS IN THE OUTER PLANETARY IONOSPHERES

During the Cassini Mission, when the spacecraft crossed the D ring, it detected a magnetic perturbation of 15-25 nT. This doesn’t arise intrinsically but induced by external currents. Such an unexpected current system can be explained in terms of the dynamo mechanism originated from the difference in the zonal wind speed at the footpoints of the planetary magnetic field lines. In Khurana et al., 2018, the total current is accordingly estimated to be as large as ∼7 MA. In this study, we apply the same pattern of the zonal wind-driven currents at the other three outer planets, and find out that the maxima of Jupiter, Uranus and Neptune are 0.20 MA, 0.44 MA and 0.63 MA.