A hybrid method for wave propagation from a localized source, with application to mountain waves

Wave propagation from a localized source into a non‐uniform medium is analysed using a hybrid method. This consists of an integral representation in the near‐field and a numerical ray tracing in the far‐field. The ray tracing includes the calculation of wave‐action density and is initialized from the stationary‐phase approximation to the near‐field integral. The method is tested on the problem of mountain waves in a turning wind, as studied by Shutts. A ray calculation with rotation added to the Shutts model is also presented and is interpreted with a simple analytical model in which the horizontal divergence of rays balances the vertical convergence of rays. In the example presented here, the inclusion of rotation speeds up the approach to wave‐breaking amplitudes.