Time evolutions of the displacement of the pore and the local magnetic field. Panel a: time profile of the displacement of the pore from 20:00 UT of 2012 February 5 to 07:00 UT of 2012 February 6. The vertical dashed line marks two times at 23:45 UT of 2012 February 5 and 02:52 UT of 2012 February 6, which divide the movement of the pore into three phases. The dashed green, red, and blue lines are the linear fits to the displacement of the pore in three phases, respectively. The mean velocity of each phase is calculated as shown by the labels. Panels b–d: time slices of the azimuthally averaged vertical field (B_z), azimuthal field (B_θ), and radial field (B_r) in the local frame. The positive and negative directions of the y-axis represents the radial distance in front of and behind the moving pore, respectively. The black arrow in panel c points to the magnetic gap between the between the amplified B_θ outside and the original B_θ within the pore. The black dotted contour overplotted in each panel refers to the boundary of the amplified azimuthal field, with a strength level of 200 G.