Reflection and conversion of magnetogravity waves in the solar chromosphere: windows to the upper atmosphere

The detection of upward propagating internal gravity waves at the base of the Sun's chromosphere has recently been reported by Straus et al., who postulated that these may efficiently couple to Alfvén waves in magnetic regions. This may be important in transporting energy to higher levels. Here we explore the propagation, reflection and mode conversion of linear gravity waves in a model atmosphere and find that even weak magnetic fields usually reflect gravity waves back downwards as slow magnetoacoustic waves well before they reach the Alfvén/acoustic equipartition height at which mode conversion might occur. However, for certain highly inclined magnetic field orientations in which the gravity waves manage to penetrate near or through the equipartition level, there can be substantial conversion to either or both up-going Alfvén and acoustic waves. Wave-energy fluxes comparable to the chromospheric radiative losses are expected.