Source of excitation of low-l solar p modes: characteristics and solar-cycle variations

We investigate various properties of the excitation source that is responsi ble for driving the acoustic p-mode oscillations of the Sun. Current prejud ice places this in the superadiabatic layer of the convection zone. We cons ider in detail how the precise nature of the resonant mode spectrum is modi fied: (i) as a result of the impact of different source-multipole mixtures; and (ii) as a function of the radial extent of the source. To do this, we model the observed resonant spectra with the solutions to a simple, one-dim ensional wave equation which is intended to describe the essential elements of the solar resonant acoustic cavity, Further, we also fit these models t o the low-l peaks in a high-resolution power spectrum generated from data c ollected by the Birmingham Solar-Oscillations Network (BiSON), We also use the extensive BiSON data set to search for variations in the source charact eristics over the solar cycle.