Phase differences between Ca ii h-G-band at the IN (left) and the magnetic canopy (right). Filled contours represent the crosspower distribution, black points denote the positions of maximum crosspower, normalized to unity for each frequency element, and the dashed contour indicates the 50% level from maximum crosspower (as an indicator of FWHM). Crosspower below 10% has been disregarded. Also, overplotted are regression lines calculated above 5.2 mHz up to the part of the distribution enclosed by the 0.5 contour. From their gradient, the corresponding phase velocities are calculated, assuming that the height separation between Ca ii h and G-band is 200 km (see text).