Temporal evolution of flux ropes (sheared arcades) revealed by NLFFF extrapolation. Panels (a)–(f) and (g1) show the top view of the flux ropes (sheared arcades), and panels (g2) and (g3) display the side view of the flux ropes. The blue-red maps in panels (g2) and (g3) are the distributions of the magnetic twist in the vertical planes based on the red and yellow cuts denoted in panel (g1), respectively.