Current ray tracing techniques make a strong assumption that the cross-sectional area of ray tubes is constant along the ray path to avoid the unbounded solution at caustics. The Gaussian beam formulation is a promising higher-order approximation than the standard ray tracing that permits the propagation of gravity waves in the presence of caustics which are ubiquitous in atmospheric mean flows. An extension of the Gaussian beam formulation is presented to consider the propagation of gravity waves in horizontally nonuniform flows. The phase of the Fourier transform of a wave train solution in the physical space can be represented as the Legendre transform of the phase. This allows a mapping for slowly varying $k$ and $l$ in which $z$ is used as the parameter. We apply the formulation to the propagation of an initial Gaussian gravity wave packet in two environments, one where the horizontally nonuniform flows tend to focus wave packets and one where tend to diffract them. There is a good agreement compared with the full nonlinear wave solution produced with WRF model. However, if the wave packet is composed with waves that are close to WKB violation, they may deteriorate the Gaussian beam solution.

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*email: pulido@unne.edu.ar
*Preference: Poster