Sound propagation in deep water with an uneven bathymetry

Abstract

Water depth has significant effects on sound propagation in underwater. A deep-water propagation experiment along two different tracks with the flat and uneven bottoms was conducted in the South China Sea in 2014. Some different propagation phenomena and horizontal-longitudinal correlations oscillation patterns were observed. Due to the reflection-blockage effects by a sea hill with height less than 1/10 water depth, transmission losses increase up to about 8 dB in the reflection area of the sea hill than that of flat bottom. Moreover, there is an inverted-triangle shadow zone with a maximal depth of 1500 m below the sea surface. The horizontal-longitudinal correlations in the reflection area of the sea hill do not show an obvious cyclical oscillation any longer as that in flat bottom environment. The differences of the transmission losses and the horizontal-longitudinal correlations oscillation patterns are explained by using the ray theory. [Work supported by the National Natural Science Foundation of China under Grant Nos. 11434012, 41561144006, and 11404366.]