Influences of the Preconditioning of Jupiter's Magnetosphere on its Response to Interplanetary Shocks: Insights from Global MHD Simulations

While it is well established that Jupiter's main auroral oval is produced by internal magnetospheric processes, such as the corotation breakdown, the total power emitted by the aurora is highly variable. It has been observed that the main oval brightens in response to solar wind dynamic pressure enhancements, often observed during impact of forward shocks. At the same time, it has also been suggested that the duration of quiet-time solar wind preceding the shock has a greater influence on the increase in emitted power than the strength of the incoming shock itself; hinting at a greater importance of internal processes such as mass loading due to Io. In this work, we use the BATSRUS global MHD model for Jupiter's magnetosphere to systematically assess the importance of the mass loading rate, IMF orientation and solar wind dynamic pressure, both separately and in-combination, to understand how these parameters affect large-scale current systems linking the magnetosphere and ionosphere. Our Jupiter model solves the ideal, semi-relativistic MHD equations in a large 3D domain and includes mass loading due to Io as source and loss terms in the MHD equations, using a steadily ionized neutral torus centered at the orbit of Io. Results from our simulations clearly show that the response of the magnetosphere to the same solar wind disturbance depends strongly on the mass loading rate associated with the Io plasma torus, as manifested in the magnetospheric configuration and amount of open-flux present in the polar ionosphere. We will also discuss the implications of our simulations for understanding the auroral response observed by the HST during Juno's approach to Jupiter in 2016.