A comparison of infrasound signals refracted from stratospheric and thermospheric altitudes

[1] Over the last several years, a large number of ground-based infrasound arrays have been established for explosion monitoring as part of the International Monitoring System of the Comprehensive Nuclear Test Ban Treaty Organization. Results from these arrays have become valuable in understanding long-range infrasound propagation in the atmosphere and complement earlier data. Two types of signals are often observed for a given source: those refracted at stratospheric heights and at thermospheric heights. In this contribution we compare several characteristics of these two signal types including observed pressure amplitude, average travel velocity, bearing, and signal duration. For this study we use archival data from atmospheric nuclear explosions, high explosive chemical explosions on the surface, earthquakes with previously detected stratospheric signals, and earthquakes for which stratospheric signals were not detected. We show that the combination of stratospheric and thermospheric signals may provide independent estimates of wind propagation conditions and source characteristics. The observations of both signal types may increase the confidence level of an infrasound signal detection.

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