Mapping the acoustic cut-off frequency in the solar atmosphere

We present the observed local dispersion relations for magneto-acoustic-gravity waves in the Sun's atmosphere for different levels of magnetic field strength. The observations were obtained with the Magneto-Optical Filter at Two Heights (MOTH-II) and SDO/HMI. We model these data with a theoretical local dispersion relation to produce spatial maps of the acoustic cut-off frequency at two heights in the Sun's photosphere. These maps have implications for the mechanical heating of the Sun's upper atmosphere by magneto-acoustic-gravity waves.