Effective roughness on the sea surface for determining variability characteristics of reflected sound waves. (1st July 2022)

• Record Type: Journal Article
• Authors: Tsukui, Tomoya; Hirata, Shinnosuke; Hachiya, Hiroyuki
• Is Part Of: Japanese journal of applied physics. Volume 61:Number SG(2022)
• Publication Date: 2022-07-01
• Subjects: sea surface -- roughness -- Rice distribution -- Reflected sound wave -- variability characteristics -- Bretshneider-Mitsuyasu -- FDTD; Physics -- Periodicals; 621.05
• DOI: 10.35848/1347-4065/ac6b80
• Languages: English
• ISSNs: 0021-4922

Abstract

Abstract: In sound wave propagation in the sea, it is important to evaluate the characteristics of sound reflection from the sea surface. The amplitude and phase of reflected sound waves fluctuate because of the changing sea surface with waves. In this study, using the finite difference time domain method and experiments in a water tank, we evaluated the variability characteristics of reflected sound waves on the sea surface generated by the Bretschneider-Mitsuyasu spectrum observed on the deep offshore coast of Japan. We introduced the concept of effective roughness of the sea surface and evaluated the variability characteristics of reflected sound waves on the sea surface. We confirmed the Rice distribution could express the amplitude variability, and the energy ratio γ is determined by the Rayleigh roughness parameter 2 k σ z 0, defined by the effective roughness σ z 0