Planetary upper atmosphere is partially ionized and in the plasma state. In general, plasma motion is strongly affected by the surrounding magnet field. Thus, it is important to understand magnet field of the planet for understanding its upper atmosphere.
Although Venus has no intrinsic magnetic field, the magnetic field exists in the Venusian upper atmosphere originated from the interaction with the solar wind. In the dayside ionosphere of Venus, magnetic rope-like fine structures, called ‘flux ropes’ have been often observed. So far some models have been proposed by previous studies, but the generation mechanism of the flux ropes has not yet been understood. We propose a new model to generate flux ropes, focusing on ‘magnetic reconnection’. Our model is validated using MHD simulation. Our study contributes for a further understanding magnetic field of Venus and its upper atmosphere.