Characteristics of ionospheric flux rope at the terminator observed by Venus Express

We investigate the characteristics of the magnetic flux ropein the Venusian ionosphere near the terminator observed by the Venus Express while previous works about flux ropeby PVO are mainly in the subsolar region. The probability to observe the flux ropebecomes larger as solar activity strengthens. A statistical work during solar maximumpresents the following characteristics. (1) The flux ropesin the terminator region have a lower spatial occurrence compared with those in the subsolar region and the spatial occurrence of the flux ropesis also getting smaller when altitude increases. (2) The scale size of the flux ropeis larger in the terminator region than that in the subsolar region and becomes larger when altitude increases. (3) In the terminator region, the flux ropeappears to have a quasi-horizontal orientation but with some cases which can be vertical at low altitude. (4) The flux ropesin high solar zenith angleregions are confirmed to have a lower helicity compared with those in low solar zenith angleregions.