Magnetoacoustic Portals and the Basal Heating of the Solar Chromosphere

We show that inclined magnetic field lines at the boundaries of large-scale convective cells (supergranules) provide ``portals'' through which low-frequency (<5 mHz) magnetoacoustic waves can propagate into the solar chromosphere. The energy flux carried by these waves at a height of 400 km above the solar surface is found to be a factor of 4 greater than that carried by the high-frequency (>5 mHz) acoustic waves, which are believed to provide the dominant source of wave heating of the chromosphere. This result opens up the possibility that low-frequency magnetoacoustic waves provide a significant source of energy for balancing the radiative losses of the ambient solar chromosphere.