2-D Propagation Modeling in Inhomogeneous Refractive Atmosphere Based on Gaussian Beams Part I: Propagation Modeling

Gaussian beams as solutions of the parabolic wave equation (PWE) in inhomogeneous 2-D media are studied. Closed-form expressions of the Gaussian beam propagation are derived, based on the assumption that the gradient of the refractive index is locally vertical, constant, and bounded within realistic values observed in the troposphere. The proposed algorithm uses the closed-form expressions of the Gaussian beams along with a multibeam expansion procedure, in order to expand any incident field and to deal with particularly important variations of the atmosphere refractive index. The method is also able to model the propagation in refractivity grids from weather forecast algorithms, such as the Weather Research and Forecasting (WRF) model. Results are accurate up to several hundreds of kilometers when compared to the PWE solved by a split-step Fourier approach in ducting condition.