Response of the Jovian Magnetosphere-Ionosphere System to the Interplanetary Magnetic Field Discontinuity: A Simulation Study

摘要

The response of the magnetosphere-ionosphere (MI) system at Jupiter to the interplanetary magnetic field (IMF) tangential discontinuity is studied via global Magnetohydrodynamics (MHD) simulations. Our results show that the IMF discontinuity, which has a transition front perpendicular to the Sun-Jupiter line, has strong effects on the Jovian MI system depending on local times and radial distances to Jupiter. The magnetospheric significant response to the discontinuity is delayed by ~2–6 hr after the encounter of the discontinuity front with the bow shock, while the delay time for the ionospheric field-aligned currents (FACs) is ~3–8 hr. The outer magnetosphere, particularly at dayside, tends to respond slightly quicker than the inner regions. At the ionosphere, the response of downward FACs is found to occur earlier than that of the upward ones by a time ranging from less than 1 hr to several hours, which is also more prominent at dayside sectors. Using a new MI mapping method with Jupiter's JRM09 magnetic field model, we reproduce for the first time the ionospheric FACs consistent with the morphology of the observed ultraviolet (UV) main auroral emissions. This indicates a potential application of the simulated upward FACs on the morphology of the UV main auroral ovals.