Investigation of the Variability Characteristics of Sound Waves Reflected on the Sea Surface Considering Surface Wavelength

Abstract

Many kinds of hydroacoustic devices are used in the field of ocean development of resources and observations. The effects of sound reflection from the sea surface are often evaluated in estimating the performance of these devices and in analyzing acoustic data obtained in actual seas. When sea surface waves are sufficiently calm, the assumption of specular reflection of sound waves is valid for the estimation of acoustic propagation characteristics. On the other hand, actual surface waves change randomly over time because of wind and gravity, and consequently reflected sound waves also fluctuate randomly. In this study, we evaluated the variability characteristics of reflected sound waves from the sea surface by acoustic simulation using the finite-difference-time-domain method. Our results clarify the effect of the wave height and wavelength at the sea surface on the variability characteristics of reflected sound waves.