Modeling infrasound propagation using the Fourier pseudo‐spectral method.

Abstract

As part of an undergoing effort to model infrasound propagation in the atmosphere, a pseudospectral time‐domain method is employed to solve the linearized equations of thermo‐viscous compressible gas dynamics in a two dimensional stratified atmosphere over a flat rigid ground surface. The system of equations is transformed from the spatial to the wavenumber domain using a spatial Fourier transform for the horizontal variables and a generalized trigonometric transform (to account for the ground surface) for the vertical variable. Time evolution is computed numerically in the wavenumber domain using a Runge–Kutta algorithm. In this initial work only viscous and thermal losses are taken into account. To handle the no‐slip condition at the ground, acoustic boundary layer theory is used. Numerical results showing the effects of complex meteorology on the the propagation of an acoustic pulse will be presented. [Work supported by US Army SMDC.]