Numerical modeling of sound propagation over various gradient continental slopes

Waveguide sound propagation in continental slope with a varying-gradient water-sediment interface and special environment is very complex. Given three different gradients for shelf break areas and a defined gradient for the continental slope, numerical simulations with a full-wave range-dependent acoustic model show that the energy distributes distinctly in different depth in the sound field, in which the slope enhancement and mudslide effect are robust with different bottom properties. The greater gradient slope transfers more energy from shallow to the deep areas, but the transmission loss will be similar between different gradient slopes with range reaching to 20 km because of the significant bottom loss. Comparing to the effects on sound intensity by varying sediment thickness and sediment sound speed gradient, the latter influences more in the bottom loss. One purpose of this paper is the feasibility of these effects in ocean continent transition zone for a short range (10 km - 30 km). Another purpose is the acoustic propagation characters affected by different gradient slope in this region. These results provide a better interpretation on acoustic signals at whole depth for deployed hydrophone in continental slope.