Diurnal and seasonal variability of Uranus's magnetosphere

Abstract

AbstractIn order to study the coupling mechanism between the solar wind and the magnetosphere, we use a numerical model to simulate the global magnetosphere and to predict potential favorable reconnection locations. We propose that a “switch‐like” magnetosphere exists at Uranus in both equinox and solstice seasons, where the planetary rotation drives the interchange between an open magnetosphere and a closed magnetosphere each Uranus day. This periodic reconnection is predicted to occur upstream of the magnetopause, with a frequency that corresponds to the planetary rotation (once per 17.24 h). The locations of the bow shock and magnetopause in our model are validated against measurements made by Voyager 2. In examining the evolution of the magnetic field configuration along with that of high plasma beta regions, which in combination indicate where the system is favorable for reconnection, we found that the reconnection that occurs is highly dependent on the rotation of the planetary magnetic field in both equinox and solstice seasons. These periodic reconnection events in our simulation support our hypothesis of a periodic “switch‐like” magnetosphere at Uranus.