Scattering of infrasound waves by anisotropic inhomogeneities of the atmosphere.

Abstract

The shaping mechanism for anisotropic wind velocity and temperature fluctuations of the atmosphere and their effect on the long-range infrasound propagation are studied. Based on the model developed for the wind velocity and temperature fluctuations induced by atmospheric gravity waves in the middle and upper atmosphere, the acoustic fields from pulsed infrasound sources (such as ground-surface explosions and volcanoes) are calculated by a parabolic equation method at different ranges from the sources (up to 300 km). The scattering of infrasound signals by highly anisotropic wind velocity and temperature inhomogeneities existing in the stratosphere and lower thermosphere is shown to significantly contribute to the stratospheric and thermospheric arrivals of the signal.