Local Infrasound Variability Related to In Situ Atmospheric Observation

Abstract

Local infrasound is widely used to constrain source parameters of near‐surface events (e.g., chemical explosions and volcanic eruptions). While atmospheric conditions are critical to infrasound propagation and source parameter inversion, local atmospheric variability is often ignored by assuming homogeneous atmospheres, and their impact on the source inversion uncertainty has never been accounted for due to the lack of quantitative understanding of infrasound variability. We investigate atmospheric impacts on local infrasound propagation by repeated explosion experiments with a dense acoustic network and in situ atmospheric measurement. We perform full 3‐D waveform simulations with local atmospheric data and numerical weather forecast model to quantify atmosphere‐dependent infrasound variability and address the advantage and restriction of local weather data/numerical weather model for sound propagation simulation. Numerical simulations with stochastic atmosphere models also showed nonnegligible influence of atmospheric heterogeneity on infrasound amplitude, suggesting an important role of local turbulence.

Seismoacoustic Analysis of Chemical Explosions at the Nevada National Security Site

“…Here we assumed a 20% error in the observed impulse ( I obs ) to estimate the variance for FSE. Full 3‐D waveform simulation with local atmospheric data can provide fairly accurate signal prediction at local distance (<10 km) reducing the uncertainty of waveform inversion (Kim, Rodgers, & Seastrand, ; Kim, Rodgers, & Wright, ). Errors in the empirical source model (equation ) has not been fully explored yet.…”

“…The accuracy of the numerical Green's function is often determined by the accuracy of atmospheric parameters used for the acoustic simulations. For FSE‐2, we used in situ radiosonde sounding data to specify the vertical profiles of atmospheric temperature, pressure, and wind (Kim, Rodgers, & Seastrand, ). For FSE‐1, FSE‐3, and FSE‐4, an operational numerical weather forecast model, called Rapid Refresh (RAP), is used for the vertical profiles.…”

“…The weather forecast service is provided by the National Center for Environmental Prediction of the U.S. National Oceanic and Atmospheric Administration (Rutledge et al, ). It is reported that local radiosonde sounding can be adversely affected by atmospheric turbulence and the resultant profiles may not necessarily represent average atmospheric conditions for sound propagation (Kim, Rodgers, & Seastrand, ). In that case, numerical weather forecast model, which assimilates various data set and reduces local noises by averaging, can be more suitable for acoustic simulation.…”

A Three‐Dimensional Array for the Study of Infrasound Propagation Through the Atmospheric Boundary Layer

“…The small-scale structure in the atmosphere can be relevant, as it contributes to phenomena such as shallow waveguide formations and scattering of infrasound (Norris et al, 2009). This has been studied previously on local and regional scales (Kim et al, 2018).…”

“…In addition to the weather models, independent temperature and wind speed measurements are analyzed at the same location as CIA. Kim et al () show that in situ measurements (radiosonde sounding data) could provide a more accurate prediction, for example, a waveguide was pronounced in the radiosonde data that was not pronounced in the weather prediction model.…”