Local infrasound propagation in three dimensions simulated with in situ atmospheric measurements

Abstract

Local infrasound propagation is influenced by atmospheric conditions. The vertical gradients of local ambient temperatures and winds can alter the effective sound speed profiles in the atmosphere and dramatically change the focusing and defocusing behaviors of acoustic waves at local distances. Accurate prediction of local infrasound amplitude is critical to estimating explosion energies of natural and/or man-made explosions, and physics-based numerical simulation that accounts for three-dimensional propagation effects should be required for that purpose. The accuracy of a numerical modeling is, however, often compromised by the uncertainty of atmospheric parameters that are used for the modeling. In this study, we investigate the impacts of local atmospheric conditions on infrasound propagation using the data from chemical explosion experiments. In situ atmospheric conditions during the experiments are measured by a combination of (1) local radiosonde soundings, (2) Atmospheric Sounder Spectrometer for Infrared Spectral Technology (ASSIST), (3) surface weather stations, and (4) a wind LIDAR profiler, which can complement atmospheric profiles for numerical simulations and capture local atmospheric variability. We simulate three-dimensional local infrasound propagation using a finite-difference method with the local atmospheric measurements, and the accuracy of the numerical simulations are evaluated by the comparison with the field observations.