Infrared signatures from bomb detonations

Remote observations of the temporal and spectral characteristics of the infrared emissions from bomb detonations have been correlated with explosion conditions. A Fourier transform interferometer was used to record spectra in the 1.6-20 mum range at spectral resolutions of 4-16 cm(-1) and temporal resolutions of 0.047-0.123 s. Field observations of 56 detonation events included a set of aircraft delivered ordinance and a series of static ground detonations for a variety of bomb sizes, types and environmental conditions. The emission is well represented by a gray body with continuously decreasing temperature and characteristic decay times of 1-4 s, providing only limited variability with detonation conditions. However, the fireball size times the emissivity as a function of time can be determined from the spectra without imaging and provides a more sensitive signature. The degree of temporal overlap as a function of frequency for a pair of detonation events provides a very sensitive discriminator for explosion conditions. The temporal overlap decreases with increasing emission frequency for all the observed events, indicating more information content at higher frequencies. (C) 2002 Elsevier Science B.V. All rights reserved.