In this paper we present a description of a software package AOS (Acoustics of Open Space) intended for real–time estimate of the mean field of sound pressure level from a remote noise source in the ground atmospheric layer. The software package allows for the characteristics of the noise source, vertical profiles of the main meteorological parameters, characteristics of the underlying surface, and the parameters of the atmospheric turbulence. Results of field tests of this package for distances from an acoustic source up to 6 km are also presented in the paper.