Top row shows the evolution of the horizontal flow modulus observed by Hinode from 29 August 2007, 10:17 UT to 31 August 2007, 10:19 UT, with a spatial resolution degraded to the one HMI/SDO. In each frame, the flow modulus is averaged over 6 h. Each frame is separated by a time step δt = 6 h. The bottom images represent the 30-min averaged horizontal flow modulus corresponding to the middle time of each averaged top modulus maps. Fields of view span 90″ × 93″ (62.25 × 67.43 Mm²).