Analysis of vector sound field in the direct-arrival zone in deep water

Vector sensors have attracted extensive interest for their abilities to measure the scalar acoustic pressure field and particle velocity at a single location in space. During a deep-water experiment held in the South China Sea in 2014, a vector sensor placed at the depth of 3146 m received the experimental signals launched from a towed transducer at 140 m depth. In the direct-arrival zone of the sound field generated by the towed source, the propagation properties of the vector sound field are studied based on the ray theory. It is shown that both the energies of the horizontal particle velocity and the vertical particle velocity are closely related to the grazing angle, which varies greatly with the horizontal distance between the source and the receiver. Then a source-range-estimation method is proposed based on the energy difference between the horizontal particle velocity and the vertical particle velocity. The proposed method is tested by experimental data.