Vertical distribution and vertical directionality of ocean ambient noise in waters with islands and reefs

Based on the seabed topography in waters with islands and reefs,as well as the ship records and the measured wind speed data,a three dimensional(3D) model of ocean ambient noise in waters with islands and reefs is established by using the 3D sound propagation theory.The vertical level distribution of ocean ambient noise caused by windgenerated noise and ship noise,the vertical directionality of ocean ambient noise caused by ship noise are simulated and calculated while the 32-elements vertical hydrophone array is located at the depth range with negative sound speed profile 265-885 m.The simulated results are in good agreement with experimental data.In the three-dimensional environment with large undulations with islands and reefs around the receiving array,wind-generated ocean ambient noise level at1 kHz is relatively uniform with depth in depth range of negative gradient sound speed profile of the deep sea channel.While the sea floor in the shipping lane area is flat and gently slanted in the area between the lane and the hydrophone array,the ship-generated ocean ambient noise level at 50 Hz increases with the depth and there is no obvious horizontal notch in vertical directionality curve of ocean ambient noise.The 3D theoretical model of ocean ambient noise established in this paper can better represent the ocean ambient noise level distribution with depth,and the vertical directionality of ocean ambient noise in waters with islands and reefs.The simulated and measured data of ocean ambient noise in waters with islands and reefs can be used as reference for practical applications and related research.