The Study On Three-dimensional High Frequency Acoustic Scattering Characteristics Of Two-dimensional Ridge Undulating Ice Surface

In the Arctic region,there are many untapped rich resources,and in recent years,climate warming has gradually melted the Arctic ice area,which also provides conditions for countries to enter the polar ice area.After entering the polar region,the influence of ice on underwater acoustic signal can’t be ignored in the process of underwater detection and communication in ice area.Therefore,it is of great strategic significance to study the acoustic scattering characteristics of ice for some scientific research activities in the polar region or for detection and communication under the ice.This paper studies and analyzes the three-dimensional acoustic scattering characteristics of two-dimensional undulating ice,verifies the calculation method of Gaussian undulating ice surface scattering intensity,extends to the undulating ice surface of ice ridge,analyzes the scattering characteristics of undulating ice layer of ice ridge under different conditions,and finally carries out the corresponding scattering intensity measurement experiments for different undulating ice surfaces,The rationality of the corresponding calculation method is verified by the experimental results.By simplifying the ice layer model,the reflection coefficient of ice layer under different conditions of single-layer ice,multi-layer ice and snow covered ice layer is analyzed,which is the basis for calculating the reflection coefficient of each bin when calculating the scattering characteristics of undulating surface.Then,for the Gaussian undulating ice layer,the scattering intensity of the two-dimensional Gaussian undulating ice layer with the same parameters is simulated by using Kirchhoff approximate analytical calculation model,numerical calculation model and finite element calculation model,and the differences between different methods are compared.The reliability of Kirchhoff approximate analysis,numerical method and finite element method is verified by experimental data,and the errors of different calculation methods are analyzed.Based on the data of polar sea ice draft,combined with the typical structure of ice ridge in the literature,a one-dimensional simple ice ridge model is constructed,and the scattering characteristics of different ice ridge models are qualitatively analyzed by using the finite element theory.According to the data of relevant literature,based on the one-dimensional ridge model,a two-dimensional ridge fluctuation model is constructed.Using Kirchhoff approximate numerical method and finite element method,the scattering intensity of the ridge model is simulated under different ridge shapes,ridge heights and acoustic incidence angles.The differences between the results of the two methods are compared,and the effects of the characteristics of ice ridge,the height of ice ridge and the incident angle of sound wave on the scattering intensity characteristics of ice ridge model are analyzed.Finally,the scattering intensity measurement experiment of two-dimensional ice ridge undulating ice layer is carried out in the laboratory pool.The experimental measurement results are compared with the simulation results of the two calculation methods to verify the reliability of the two calculation methods.The difference between the calculation results of different methods and the experimental results are analyzed.Finally,the Kirchhoff approximate numerical method is used to simulate and analyze the polar large-scale ice ridge.