Laws of weakening infrasonic signals from the directed sources in the shallow sea

In the development of the fundamental idea of the professor G. I. Bykovtsev, who proposed to replace the field of the complex three-dimensional spatially developed moving source with the field of equivalent multipole emitter, the possibility of the simplified description of the laws of attenuation of the infrasonic signals from these sources is investigated. In connection with Pekeris's waveguide we obtain the analytical dependences, which characterize the attenuation of the signal at the distances up to 100 km and more. Formulas are obtained for different types of multipoles and different distance intervals to the source. It is shown that these dependences give the sufficiently precise description of the averaged field and differ essentially for the horizontally and vertically oriented multipoles. The approximating relationships, which determine decay laws for the small, medium and great distances considering the influence of the horizons of detection and emission, sound frequency, depth and characteristics of the bottom of waveguide.