Evolution of f-mode-filtered inward–outward travel times for the average supergranule. Top: outflow. Bottom: inflow. The frames, from top left to bottom right, span a total of eleven days in non-overlapping steps of eight hours. The central frame (red outline) is for the reference time, Δt = 0. We note that the color scale is different for each individual frame; saturation is reached at the maximum absolute value (given by the lower label boxes) of the respective frame. The color map is symmetrized around zero; outflows are red and inflows are blue.