Numerical simulation for three dimensions infrasound propagation in shadow zone using a one-way approach

The propagation of infrasound through the atmosphere is influenced by factors such as temperature and wind speed gradients, topography, and geometry of the source. These factors can create shadow zones where geometric acoustic approximations are no longer valid. For instance, during the 2007 Carancas meteorite impact, the closest infrasound station was located in a shadow zone, and conventional ray-tracing models were unable to account for signals detected at this station. To address this challenge, our study proposes a 3-D numerical method that reconstructs the observed signals without relying on geometric acoustics assumptions, while avoiding the computational expense of full direct numerical simulations. Our approach is based on the FLHOWARD3D model, which employs a unidirectional approximation for nonlinear acoustic wave propagation in heterogeneous media. To take advantage of the unidirectional approximation, a domain coupling strategy was developed and rigorously validated. The method’s performance in shadow zones is first evaluated by comparing it with analytical solutions. Subsequently, the method is applied to the Carancas scenario, incorporating both the nonlinear characteristics of the source and atmospheric heterogeneities. This work opens up prospects for improved infrasound prediction in shadow zones and enables the inference of key properties related to the source and propagation medium.