Comparison between magnetic coplanarity and MVA methods in determining the normal of Venusian bow shock

With the measurements of magnetic field of Venus Express (VEX), magnetic coplanarity and minimum variance analysis (MVA) methods are analyzed and tested their validity to determine the normal of Venusian bow shocks. It is found the MVA method is the better than magnetic coplanarity, and 95% shock crossings can be accurately determined by the method. However, the occurrence of the shock which is not determined accurately by the magnetic coplanarity increases with the decrease of the solar zenith angle (SZA). At the same time, compared with quasi-parallel shocks, magnetic coplanarity fails for more quasi-perpendicular shocks.