Time-dependent coupling of solar oscillations

We investigate the effects of a large-scale time-dependent flow in the solar convection zone on the solar p-mode oscillations. The theory of time-dependent perturbations is applied, and we concentrate on flow fields that can be described by a single harmonic in space and time. An iterative method of obtaining approximate analytical solutions to the equations of the coupled oscillator is outlined. Example calculations are presented for the special case of two coupling partners. Special attention is paid to the resonance that occurs when the time dependence of the flow meets the beat frequency of two p modes. We conclude that time-dependent flow fields in the solar convection zone may diminish the height of the peaks in the oscillation power spectrum, and may contribute to their asymmetry, broadening, and effective shift.