Study On Characteristics Of Underwater Acoustic Channel Under Multi-Layer Ice-Covered Interface

Due to the unique geographical location of the Arctic,as the global temperature warms,the Arctic sea ice melts sharply,and the Arctic waterway is expected to be developed.The Arctic region is of great significance both in terms of strategy and civil use.The surface of the Arctic Ocean is covered with ice,which makes it difficult to study the Arctic Ocean.The north pole surface is covered with ice,forming a unique positive sound velocity gradient profile of the North Pole.When the sound source is close to the ice surface,the sound line is refracted upward and curved,reflected with the ice surface,and then refracted to form a surface channel.The reflection of the ice layer plays a vital role in the propagation of sound,which affects the sound field under the Arctic ice.In this paper,a method for calculating the reflection coefficient of multi-layer ice and snow acoustic waves based on boundary conditions is studied.This method is called overall matrix.Compared with the impedance transfer method,the correctness of the overall matrix method is verified.The effects of different frequencies,ice layers,snow layers and other conditions on the reflection coefficient of sound waves are analyzed.The reflection coefficient is combined with the sound field simulation model Bellhop to simulate the Arctic sound field.Based on the measured Arctic ice parameters,a layered ice and snow model was established to analyze the loss of ice propagation,the sound ray diagram and the impulse response.Comparing the effects of the channel under the condition of layered ice and single layer ice,the correlation between the two types of ice channels at the long distance is very poor,indicating the necessity of layered ice.The characteristics of sound propagation under different frequencies,ice thickness and snow layer conditions are compared,and the factors affecting the sound field are analyzed.The sound field simulation results are compared with the test.The Arctic test and the Russian winter test were carried out respectively,and the propagation loss at different depths under the condition of constant receiving distance was measured.Compare the simulation with the test and analyze the effectiveness and problems of the simulation.