Generation of acoustic-gravity waves by a submerged monopole source located near the water-air interface

Abstract

Powerful underwater explosions and certain natural sources, such as underwater landslides, generate very low-frequency waves in water and air, for which both fluid buoyancy and compressibility simultaneously serve as restoring forces. In this paper, analysis of sound transmission through air-water interface is extended to acoustic-gravity waves (AGWs). It is found that, as for sound, the interface becomes anomalously transparent for sufficiently shallow compact sources of AGWs. The increase of wave power flux into air due to diffraction effects can reach several orders of magnitude. Physical mechanisms responsible for the anomalous transparency are discussed. Excitation of an interface wave by an underwater source is shown to be an important channel of AGW transmission into atmosphere, which has no counterpart in the case of sound.