Top panel: 2D statistical distribution of PA and PA ± 180° for all single pulses, showing only PA values within the main pulse region. The dashed black ellipse corresponds to the two areas where PA jumps occur most frequently, with black dots indicating the centers of these ellipses. The two dashed red lines mark the longitude positions of the black dots, labeled longitude I and II, respectively. The PA range for these two dashed red lines spans from the value of the black dots minus 135° to the value plus 45°. Bottom panel: Curve of the PA for the total average pulse profile.