Magnetic field configuration in the Venus ionosphere

We investigated the magnetic field configuration in the Venus ionosphere, from the data (orbit 1-600) obtained by Pioneer Venus Orbiter (PVO). The magnetic field lines were draping the Venus ionosphere, but the magnetic field lines were opened to the interplanetary space in the nightside ionosphere. We found the closed magnetic field line around Venus near the magnetic equator at 600-800 km altitudes during the high solar wind dynamic pressure. The result shows that magnetic reconnection occurs in the Venus nightside ionosphere.