Variations in Venusian magnetic topology during an interplanetary coronal mass ejection passage: A multifluid magnetohydrodynamics study

The global effects on Venusian magnetic topology and ion escape during the significant solar-wind disturbances caused by the interplanetary coronal mass ejection (ICME) remain an open area of research. This study examined a particularly intense ICME interaction with Venus on November 5, 2011, using a global multifluid magnetohydrodynamics (MHD) model. To evaluate Venus’s time-dependent response to the event, the model was driven by varying solar-wind input conditions. The numerical results indicate that there are more draped and open magnetic-field lines at low altitudes due to deeper interplanetary magnetic-field (IMF) penetration resulting from the enhanced solar-wind dynamic pressure during the ICME. Conversely, the closed magnetic-field lines gradually decrease after the ICME reaches Venus due to the reduction in magnetic reconnection influenced by a shift in the magnetic topology direction. In the magnetotail escape channel, the increased presence of open field lines intersecting the ionosphere promotes greater ion outflow, thereby facilitating ion escape. The escape rates of planetary ions are enhanced by about an order of magnitude under ICME sheath conditions. This comprehensive investigation of the global distribution of magnetic topology around Venus provides valuable insights into the magnetic-field properties and ion escape during disturbed conditions.