Localization of sources on the ground from an elevated acoustic sensor array.

Abstract

Acoustic sensor arrays suspended below tethered aerostats are employed for localization of sources on the ground. The aerostats can be elevated up to 1–2 km above the ground. Since the values of temperature and wind velocity vary significantly from the ground up to such heights, sound refraction should be taken into account when determining the source coordinates. Previously [Ostashev et al., J. Acoust. Soc. Am. 122, 3084 (2007)], a theory was developed that enables determination of the source coordinates from the direction of sound signal propagation as measured by the sensor array, its coordinates, and the vertical profiles of temperature and wind velocity. However, these profiles can be known only with some errors and uncertainties. In the present paper, the effects of uncertainties in the vertical profiles of temperature and wind velocity on determining the source coordinates are studied. To this end, the vertical profiles are approximated with the Monin–Obukhov theory of similarity. The uncertainties in the profiles are modeled by allowing the surface roughness length, the friction velocity, and the surface sensible heat flux vary from their mean values. Some of the results obtained are compared with experimental data.