Upper panel: Time-distance plot of the azimuthally averaged values of magnetic field inclination derived from HMI observations in the ROI marked by the dashed red lines in Fig. 1 at the photospheric level. The white and black lines outline the mean position of the umbra/penumbra and penumbra/quiet Sun boundaries, respectively. Lower panels: Same as upper panel but for the extrapolations at 0 Mm, 7.9 Mm, and 15.8 Mm. The azimuthal average of γ is only applied in pixels where B > 200 G.