Influence of oceanic fronts on the low-frequency sound propagation in full waveguides of the shallow sea

Aiming at the problem of the influence of the ocean front on low-frequency sound propagation in the shallow sea, based on the finite element method, the influence law of front properties, front gradient and front slope on low-frequency sound propagation characteristics is simulated and analyzed under the calculation model of full-waveguide sound field in the shallow sea, and the physical explanation is given in combination with the ray acoustic theory. The results show that the front with a negative sound velocity gradient will cause downward deflection of sound rays, increase the grazing angle of sound rays entering the seabed, and enhance the leakage effect of sound energy to the seabed, while the front with a positive gradient will have the opposite effect; With the decline of the absolute value of the front sound velocity gradient, the grazing angle of the sound line incident on the seabed in the negative gradient front gradually decreases, and the span gradually increases, which will weaken the leakage effect of sound energy to the seabed, while the positive gradient front will slightly enhance the leakage effect of sound energy to the seabed; With the decrease of the front slope, the grazing angle of the sound ray incident on the seabed increases gradually, and the span decreases, which causes the peak position of the sound energy leakage to move towards the front tilt direction.