Photospheric horizontal and line-of-sight velocity maps at three selected times corresponding to Fig. 2. Panels a–c: the background greyscale image shows the continuum image, and the overplotted arrows represent the horizontal flow fields (V_x, y) derived by using the DAVE4VM method, with color indicating the velocity. Panels d–f: HMI dopplergrams (V_los) with the blue and red patches indicate upflows and downflows, respectively. The black contours represent the pore boundaries with intensity level I/I_qS = 0.9. The green contours in panel e outlines the region with horizontal velocity greater than 500 ms⁻¹. The vertical red line in each panel marks the X position of the moving pore.