Regional and global scale propagation simulations of infrasonic signals

Abstract

Infrasonic signals are frequently observed at large propagation distances of 100s to 1000s of kilometers from the source and, in extreme cases, signals have been observed to circle the globe. Simulating acoustic propagation at these large scales requires a framework that not only accounts for 3D propagation effects including along- and cross-path winds, but also for the non-Cartesian geometry of the atmospheric layer surrounding the globe. Furthermore, interaction of propagating infrasonic energy with terrain features is known to have a notable impact on signals, particularly when the wavelength of the signals is comparable to the terrain scale. Finally, spatial variations in the atmospheric structure beyond simple stratification can have significant impacts on propagation paths. Numerical tools for acoustic ray tracing that account for these and other complications will be detailed and demonstrated using several recent infrasonic events of interest.