Solar cycle variation of the venus magnetic barrier

Abstract

Although there is no intrinsic magnetic field at Venus, the convected interplanetary magnetic field piles up to form an induced magnetosphere around the planetary ionosphere. Previous investigations show that the magnetic barrier, the part of the induced magnetosphere in the dayside inner magnetosheath, can act as an effective obstacle to the solar wind during solar maximum, and the magnetic barrier can stop the solar wind even during solar minimum. In this study, we perform a comprehensive statistical study of the magnetic barrier near the terminator during almost a complete solar cycle by using Venus Express magnetic data. The magnetic barrier configuration is located at the dayside even near the terminator and a hemispheric asymmetry exists during the whole solar cycle. We also demonstrate that the general magnetic barrier configuration is controlled by the interplanetary magnetic field orientation and solar cycle dependent. The magnetic barrier under IMF quasi-perpendicular to the solar wind flow is stronger than quasi-parallel to the solar wind flow during the solar cycle, and this difference becomes larger with the increase in solar activity.