Estimation of bolide energy using observed infrasound signals

Abstract

The acoustic amplitude-yield relationships including formal errors for a population of large and well-observed (greater than 0.05 kton) bolide events have been investigated. Using various signal measurements as a function of range, these data have been calibrated against optical yield estimates from satellite measurements. A correction for the presence of stratospheric winds has also been applied to the observations and is found to greatly improve the relationship correlation, remaining scatter may be due to variations amongst the fireball population such as differing burst altitudes, greater or lesser amounts of fragmentation or the variability in the magnitude of stratospheric winds, which can during certain times of the year be comparable to or exceed the strength of the winds themselves. Comparison to point source, ground-level nuclear and high explosive airwave data with similar yields shows that observed bolide infrasound is consistently lower in amplitude. This downward shift relative to nuclear and HE data is interpreted as due in part to increased weak nonlinearity during signal propagation from higher altitudes. This is a likely explanation, since mean estimates of the altitude of maximum energy deposition along the bolide trajectory was found to be between 20–30 km altitude for this fireball population.