Solar seeing and the spatial properties of the five-minute oscillations

A numerical simulation of observations of the spatial properties of the five-minute oscillations is carried out, assuming the oscillations are internal gravity waves excited by granular convection according to the theory of Thomas et al. (1971). The simulation includes the effects of seeing and finite aperture. The details of the simulation are chosen to model the observational method of Frazier (1968a, b). The results show that the peak in the observed power spectrum of the oscillations can occur at a wavelength considerably longer than the true wavelength of the oscillations. In particular, the peak in Frazier's observed power spectra at wavelength 5000 km is consistent with the considerably shorter true wavelength 1500 km predicted by the gravity wave theory.