The use of infrasound from repeating explosion sequences in Oklahoma to probe the atmosphere

Abstract

Infrasound waves are sensitive to atmospheric processes that are unresolved in numerical weather prediction models, and to atmospheric properties at altitudes that are poorly constrained by observations. We report on the use of infrasound observations to probe atmospheric phenomena occurring over temporal scales from less than one hour to days, and at altitudes that extend up to the stratopause. Two measurement campaigns were conducted to capture infrasound signals from repeating explosion sequences from the McAlester Army Ammunition Plant in Oklahoma. The first campaign captured infrasound signals propagating in a tropospheric waveguide, while the second captured signals propagating in a stratospheric waveguide. In both cases, we resolve sub-hour variations in infrasound signal characteristics that we show are related to unresolved atmospheric phenomena. We further resolve day-to-day variations for the two different waveguides and assess how well these longer-term variations can be explained using meteorological models. Using a normal-mode code based on a Chebyshev collocation method, we also compared ground infrasonic recordings and numerically synthesized pressure waveforms. The results provide insight into the value that infrasound measurements can provide for meteorology over different temporal and spatial scales.