Response of Venusian plasma environment to the interplanetary coronal mass ejections on 5 November 2011: A magnetohydrodynamics simulation study

Context. As an unmagnetized planet, Venus lacks an intrinsic magnetic field, leading to the direct interaction with the solar wind, which results in differences in physical processes within its magnetosphere–ionosphere (MI) system compared to Earth. With intense solar wind disturbances, it has been suggested that interplanetary coronal mass ejections (ICMEs) have a pronounced effect on Venus. Aims. This study aims to investigate the responses of the Venusian plasma environment to ICMEs. A simulation driven by a real ICME event that occurred on 5 November 2011, was conducted to systematically and quantitatively analyze the plasma processes in Venusian magnetosphere. During this event, the solar wind dynamic pressure at the model input increased by a factor of up to 4.8, while the interplanetary magnetic field (IMF) strength was enhanced by a factor of 1.9. Methods. The numerical simulation for Venusian plasma environment uses a multi-fluid global magnetohydrodynamics (MHD) model, coupled with the uniform neutral atmosphere. Utilizing the upstream magnetic field data from VEX and idealized solar wind plasma parameters as model inputs, we examine the response of Venusian plasma environment after the ICME arrival. Results. Venusian plasma environment and boundaries respond rapidly on the order of minutes. During the ICME, the subsolar bow shock location exhibits an inverse-linear proportionality to the fast magnetosonic Mach number. Meanwhile, the variation in boundaries’ locations demonstrates that high solar wind dynamic pressure and an enhanced IMF display compressive and expanding effects, respectively. The total integral of the ions’ escape rate shows that under ICME passage, the O+ escape rate of Venus exhibits a sustained increase, from 6.0 × 1024 s−1 to 3.0 × 1025 s−1. Both solar wind dynamic pressure and IMF strength enhance ion escape, with dynamic pressure dominating this process. Conclusions. The simulation driven by a real ICME event demonstrates severe, rapid, and complex responses of Venusian plasma environments, accompanied by an order-of-magnitude enhancement O+ escape rate. These results could advance the understanding of the long-term evolution of terrestrial planets and provides references for the scientific targets of future missions.