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Session 69 - The Solar Dynamo and Helioseismology.
Display session, Thursday, June 13
The effects of convection on p mode frequencies and linewidths are not completely understood. This paper takes an approach based on geometrical optics. We have written computer code which uses EBK quantization to determine the eigenfrequencies of a ray with a given dispersion relation traveling through a plane-parallel medium with variations in the local wave velocity. The path of one ray is calculated for many orbits as it comes arbitrarily close to every point in its region of propagation. After sampling the entire domain, the path itself (specifically, the wavenumber as a function of position) is used to find the eigenfrequencies of the modes. This method proved to be quite robust in finding frequencies for a number of trial simulations, including horizontal advective motions and large wave speed perturbations. By coupling my ray-tracing program to snapshots of detailed simulations of convection in a plane-parallel atmosphere, we can determine both frequency shifts and line widths of p modes.
Program listing for Thursday