资源环境科技发展态势分析平台

Large-scale magnetic fields have been observed in Venus' ionosphere by both the Pioneer Venus Orbiter (PVO) and Venus Express spacecraft. In this study, we examine the formation and evolution of the large-scale magnetic field in the Venus ionosphere using a sophisticated global multispecies Magnetohydrodynamics (MHD) model that has been developed for Venus (Ma et al., 2013, ). A time-dependent model run is performed under varying solar wind dynamic pressure. Based on model results, we find that (1) the initial response of the induced magnetosphere is fast (similar to min), (2) a large-scale magnetic field gradually forms in the ionosphere when the solar wind dynamic pressure suddenly exceeds the ionospheric thermal pressure, (3) both the penetration and decay of the large-scale magnetic field in the ionosphere are slow (similar to hr), and (4) the ion escape rate has a nonlinear response to the change of solar wind dynamic pressure.