Wave modulation and wave sources in the solar convection zone

We investigate the behavior of upward running sound waves in the lower phot osphere by means of a 2-hour time series of FPI-filtergrams and a correspon ding series of white-light images. From the FPI-filtergrams we obtain veloc ities in two heights in the solar photosphere. Using specific filters in th e kh-v-space, we extract running sound waves from the velocity time series and the granulation from the white-light series. The relation between granu lar structure and wave amplitude is examined. To this end the granulation i mages are subdivided into intensity classes. The amplitudes of the waves ar e extracted on the pixel maps corresponding to these classes. We find hints for wave modulation due to the inhomogeneities in the solar convection zon e: The behavior of the wave amplitudes meets theoretical predictions with r espect to frequency- and height-dependence. The dependence on the horizonta l wave number meets the predictions too, but due to low wave coherence at h igh wave numbers no definitive statement is possible. Further the darkest l ocations in the granulation are preferred by waves of increased amplitudes. There also seems to be a preference for the brightest granular regions. In both cases the behavior of the waves can be well described by subsurface s ound sources. This is confirmed by comparison of the data with a simple mod el of a subsurface sound source.