High-frequency peaks in the power spectrum of solar velocity observations from the GOLF experiment

The power spectrum of more than 630 days of full-disk solar velocity data, provided by the GOLF spectrophotometer aboard the Solar nod Heliospheric Ob servatory, has revealed the presence of modelike structure well beyond the acoustic cutoff frequency for the solar atmosphere (nu(ac) similar to 5.4 m Hz). Similar data produced by full-disk instruments deployed in Earth-based networks (BiSON and IRIS) had not shown any peak structure above nu(ac): t his is probably due to the higher levels of noise that are inherent in Eart h-based experiments. We show that the observed peak structure (nu(ac) less than or equal to nu less than or equal to 7.5 mHz) can be explained by a si mple two-wave interference model if the high-frequency waves are partially reflected at the back side of the Sun.