Topographically Scattered Infrasound Waves Observed on Microbarometer Arrays in the Lower Stratosphere

• Published in: Earth and Space Science
• Main Authors: Bird, Elijah J., Lees, J. M., Kero, J., Bowman, D. C.
• Language: unknown
• Published: 2023
• Subjects: 58 GEOSCIENCES; Northern Sweden
• Online Access: http://www.osti.gov/servlets/purl/1870466; https://www.osti.gov/biblio/1870466; https://doi.org/10.1029/2022ea002226

When an acoustic wave strikes a topographic feature, some of its energy is scattered. Sensors on the ground cannot capture these scattered signals when they propagate at high angles. We report observations of upwardly-scattered acoustic waves prior to refraction back to the ground, intercepting them with a set of balloon-borne infrasound microbarometers in the lower stratosphere over northern Sweden. We show that these scattered waves generate a coda whose presence can be related to topography beneath balloons and low-altitude acoustic ducts. The inclination of the coda signals changes systematically with time, as expected from waves arriving from scatterers successively closer to receivers. The codas are present when a temperature inversion channels infrasound from a set of ground chemical explosions along the ground, but are absent following the inversion's dissipation. Since scattering partitions energy away from the main arrival, these observations imply a mechanism of amplitude loss that had previously been inaccessible to measurement. As such, these data and results allow for a better comprehension of interactions between atmospheric infrasound propagation and the solid earth