Sound Propagation with Undulating Bottom in Shallow Water

Abstract

An undulating bottom in shallow water has a significant effect on sound propagation. An acoustic propagation experiment was carried out in the East China Sea in 2020. Measurements along two separate propagation tracks with flat and undulating bottoms were obtained. Abnormal transmission losses (TLs) were observed along the track with the undulating bottom. By using the parabolic equation model RAM and ray theory, these abnormal TLs and the distribution of the sound field energy were analyzed. Numerical simulations indicate that under the shallow water condition with a negative thermocline and for a high frequency (1000 Hz), the incidence and reflection angles of sound rays on the sea bottom are changed due to the undulating sea bottom. The larger the inclination angle of the undulating bottom, the greater the grazing angle changes. These angles changes lead to different sound propagation paths for the undulating bottom and the flat bottom, resulting in the difference of TLs at a certain distance and depth. The undulating bottom will cause energy convergence in the mixed layer when the source and receiver locate above the thermocline.

Underwater Acoustic Propagation using Monterey-Miami Parabolic Equation in Shallow Water Kayeli Bay Buru Distric

“…Overall, sediments can influence the ray path of acoustic signal propagation in shallow waters by influencing seafloor characteristics, acoustic signal reflection, acoustic velocity, and the detection and acoustic characterization of seafloor sediments. Therefore, the characteristics of shallow water sediments need to be considered when simulating the propagation of acoustic signal beam paths (Liu et al,. 2021) The result of this difference in impedance is what causes the differences seen in the propagation between images 1 and 2.…”

Research on Underwater Collaborative Detection Method Based on Complex Marine Environment

“…The results show that the operating frequency and depth of sonar have a significant impact on the operating distance of sonar. In recent years, more and more scholars have begun to study the construction of sonar detection and analysis models, quantitatively analyzing the impact of the marine environment on detection capabilities, and have achieved relatively abundant results [17][18][19][20][21][22][23]. It can be seen that marine environmental factors have a significant impact on the performance of sonar equipment, and it is urgent to establish a suitable sonar detection capability analysis model to analyze the impact of marine environment on sonar detection capability.…”

Modeling Techniques for Underwater Acoustic Scattering and Propagation (Including 3D Effects)

“…Papers of the first kind [2][3][4][5][6][7] are related to new or insufficiently investigated physical effects related to sound propagation in complex media with various inhomogeneities, including undulating bottom [3], variations in acoustical properties of the bottom across the propagation path [2], the presence of seamounts [4], and bubbles [6] or internal waves [7] in the water column. It is remarkable that both new 2D [3,7] and 3D [2,4] effects are reported in these papers. In most of them, new interesting features of sound fields are investigated both theoretically and experimentally, and the modeling results are compared with the measurement data.…”

“…In most of them, new interesting features of sound fields are investigated both theoretically and experimentally, and the modeling results are compared with the measurement data. The spectrum of theoretical approaches used by the authors covers almost all techniques existing in theoretical underwater acoustics, including parabolic equations theory [3], normal modes [2], and ray-theoretical considerations.…”