A universal expression for the low-frequency attenuation coefficient in the surface duct

A study developed a universal expression for the attenuation in the surface duct through simulations and comparison with experimental data from a deep water environment. A vertical uniform linear array of 18 hydrophones spaced at 4 m was deployed near the ocean surface. The topmost hydrophone was 30 m below the ocean surface. Explosive sound sources were deployed every 1 km when the ship was moving away from the vertical array to a distance of 40 km. The preset explosion depth was 300 m and the mass of TNT in the explosive charges was 1 kg. A Conductivity-Temperature-Depth (CTD) sensor was used to measure the sound speed profile (SSP) at the array location before the track.