Effects of inclined sea bottom on acoustic propagation characteristics in shallow ocean fronts

The ocean front has always been the research focus of many scholars, but due to the complex ocean environment and high monitoring cost, there has been no systematic study on the offshore ocean front. In view of the current research situation, the ocean front model suitable for offshore marine environment is established and the sound velocity profile of seawater layer is given. Secondly, we have developed the formula for calculating sound energy flow. In this study, the influence of ocean front environment on sound propagation is studied by using finite element method and gamma acoustics. The results show that the front propagating from warm water to cold water strengthens the leakage of acoustic energy to the sea bottom. With the increase of sea bottom tilt, the leakage of sound energy to the sea bottom in the frontal region gradually decreases. However, acoustic energy leakage behind the front will increase. In front of the frontal region, the grazing angle of the sound line in contact with the sea bottom decreases gradually due to the increase of the tilting degree of the sea bottom, so the grazing angle is smaller when the sound line enters the frontal region. Although fronts increase the number of acoustic contact with the sea bottom, the effect of sea bottom tilt is more significant. Thus, as the tilting of the sea bottom increases, acoustic energy gradually diminishes leakage to the sea bottom.