Phase of the cross-spectrum of the images at the reference level and at line cord 16 as function of the spatial frequency. The spectrograph slit is oriented along the north-south axis. Red symbols: results obtained with the Hinode data (in blue: Themis data). Upper panel: results for regions at cosθ = 0.74 in the southern hemisphere on the solar polar axis. Lower panel: results at cosθ = 0.74 in the northern hemisphere.