Magnetic field topology in the X−Z plane for B_Z = 5 nT (panel a) and B_Z = −5 nT (panel b). The solar wind conditions are IMF B_X = B_Y = 0 nT, P_d = 1 nPa (n = 4.0 cm⁻³, V_X = −400.0 km s⁻¹ ). The color bar shows the solar wind total pressure (nPa) in each panel. The solid black lines are the magnetic field lines. The red circles and white squares represent the MPB location identified by the method in this work and the pressure balance (P_th + P_d)/P_B = 1.0. The red dashed line is the model result of Vignes et al. (2000).