  Aims. With the Solar Optical Telescope on Hinode, we investigate the basic
properties of high-degree solar oscillations observed at two levels in the
solar atmosphere, in the G-band (formed in the photosphere) and in the Ca II H
line (chromospheric emission).
  Methods. We analyzed the data by calculating the individual power spectra as
well as the cross-spectral properties, i.e., coherence and phase shift. The
observational properties are compared with a simple theoretical model, which
includes the effects of correlated noise.
  Results. The results reveal significant frequency shifts between the Ca II H
and G-band spectra, in particular above the acoustic cut-off frequency for
pseudo-modes. The cross-spectrum phase shows peaks associated with the acoustic
oscillation (p-mode) lines, and begins to increase with frequency around the
acoustic cut-off. However, we find no phase shift for the (surface gravity
wave) f-mode. The observed properties for the p-modes are qualitatively
reproduced in a simple model with a correlated background if the correlated
noise level in the Ca II H data is higher than in the G-band data. These
results suggest that multi-wavelength observations of solar oscillations, in
combination with the traditional intensity-velocity observations, may help to
determine the level of the correlated background noise and to determine the
type of wave excitation sources on the Sun.
