On acoustical impulse propagation in a moving inhomogeneous atmospheric layer

In the present work a solution is obtained by the method of normal modes, which describes the sound field of a point impulse source in the atmosphere with definite temperature and wind velocity profiles and ground impedance. This solution describes the impulse shape transformation in different directions relevant to wind velocity involving the low-frequency case, when the ray approach becomes invalid. The impulse shape evolution during guided and antiguided propagation (in the shadow region) is in good qualitative agreement with the shape observed in the experiment. The change of the impulse shape in time is observed in the experiment during transition of the boundary atmospheric layer from a convective state to one with a stable temperature inversion. The experimental measurements and theoretical estimations show that the nearground acoustical waveguide is formed mainly due to wind stratification in the boundary layer. Solving of the direct problem also shows a principal possibility of inclined sounding of the boundary atmospheric layer.