Upper and middle panels: two-dimensional rendering of the shear angle θ and the inclination angle ψ along a vertical cut at y =  −0.3. θ and ψ values are there measured from the local magnetic field components. The full (resp. dashed) contours correspond to negative (resp. positive) values and are labeled in degrees. Lower panels: three-dimensional zoom of the same field lines as drawn in Fig. 3, showing the time-evolution of their vertical straightening around the PIL. These panels all together show a gradual decrease of shear and inclination for the low-altitude magnetic fields, before they reconnect.