The dynamic response of Jovian magnetotail reconnection to enhanced solar wind ram pressure

In this study, we employ the Grid Agnostic Magnetohydrodynamic (MHD) for Extended Research Applications (GAMERA), a high-resolving power, three-dimensional global MHD model, to simulate magnetotail reconnection in Jupiter’s magnetosphere. While previous satellite observations have provided initial statistics on magnetotail reconnection properties at Jupiter, they have been limited in space-time coverage, leaving the dynamic process of Jovian magnetotail reconnection and its response to the solar wind (SW) poorly understood. Using MHD simulations, we quantitatively analyze the temporal evolution and spatial dependence of nightside reconnection in Jupiter’s magnetotail under ideal quiet and enhanced SW conditions. Our results demonstrate that magnetotail reconnection tends to occur in the midnight and post-midnight sectors, with a low occurrence in the pre-midnight sector, consistent with both Galileo and Juno observations and predictions by Delamere and Bagenal (2013). The MLT-radial distribution of magnetotail reconnection is broad, indicating that Jovian magnetotail reconnection is always dynamic rather than steady-state. Enhanced SW ram pressure can decrease the MLT coverage of magnetotail reconnection by compressing Jupiter’s magnetosphere. However, the occurrence and radial distribution of magnetotail reconnection near the midnight and post-midnight sectors are augmented by SW compression beyond ~60 RJ, but are not significantly impacted by SW compression within ~60 RJ. Conversely, SW compression suppresses reconnection in the pre-midnight sector, leading to a stronger dawn-dusk asymmetry in the occurrence and location of magnetotail reconnection. This study validates the applicability of the GAMERA code for simulating Jupiter’s magnetosphere and provides complementary insights into the dynamic structure and the SW response of Jupiter’s magnetosphere.