Current systems in the Jovian magnetosphere

The plasma dynamics in the Jovian magnetosphere is characterized by rapid rotation of the planet. In this paper, a new magnetohydrodynamic (MHD) simulation scheme is developed to precisely calculate the current systems in the Jovian magnetosphere and to relate them with the plasma dynamics. A field-aligned current (FAC) pattern that is expected for the ionosphere to drive the corotation is reproduced in the present simulation result with current away from the ionosphere at lower latitudes and current toward the ionosphere at higher latitudes. In the magnetospheric region, a thin equatorial current sheet with eastward current flowing around Jupiter (ring current) dominates in the middle magnetosphere. By tracing current lines, it is found that the upward FAC on the low-latitude side in the ionosphere is first connected to the ring current and then to the Chapman-Ferraro current through the plasma sheet current. Downward FAC in the high-latitude ionosphere is spirally connected to the tail lobe. From the distribution of J-E, the places of dynamo and energy consumption region are investigated to understand the energy balance associated with the corotation by magnetosphere-ionosphere (M-I) current system. From these analyses, the FAC, ring current, the Chapman-Ferraro current and plasma distribution in the Jovian magnetosphere are understood as a self-consistently organized structure through corotation and confinement. In addition, some interesting field-line structures and plasmoid formation are found by tracing the magnetic field line.