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Aims. We show that the spatial distribution (and its variation with frequency) of the power spectra of the velocity and intensity signals, in and around solar active regions, is a manifestation of the interaction of acoustic waves at the magnetic canopy. Methods. We analysed 6 h of simultaneous, full-disk, velocity and intensity images obtained using the MOTH instrument tuned in the Na D2 line at 589 nm and K D1 line at 770 nm, and full-disk velocity images from the SOHO/MDI experiment using the Ni line at 677 nm. Results. We propose that more than one type of magneto-acoustic-gravity wave is required to explain the well-known phenomena of p-mode absorption and power halos.

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Abstract. The origin of solar oscillations has not yet been clearly determined. The downflows due to convective rapid cooling at the surface have been invoked as a possible source. In this paper we investigate the properties of the source as inferred from the local analysis of the intensity-velocity phase differences. The same spatial and temporal characteristics of other observed events and their correlation with the Hα bright points suggests downward plasma jets related to explosive chromospheric evaporation to be another possible candidate.