(a) Overview of the north–south asymmetric polar outflows during a typical southward IMF condition, under the influences of a B_x component. The gray lines are the magnetic field lines, the white arrows denote the flow vectors, and the red line denotes the specified streamline. The background colors represent the thermal pressure in the noon–midnight meridian plane. (b) The forces acting on the polar outflows along the specified streamline. The orange, green, and red lines denote the thermal pressure gradient, Ampère, and total forces along the streamline, respectively. The blue line represents the velocity.