Influence Of Ocean Hydrodynamic Phenomena On Spatial Characteristics Of Three-Dimensional Sound Field

The hydrodynamic phenomena in the ocean have an obvious effect on the acoustic propagation process in deep and shallow waters,especially on the acoustic field at the far-field position.It has important application value for the use of underwater acoustic equipment,underwater acoustic countermeasure mission planning,underwater acoustic detection and early warning,etc.At present,there are many research results in the two-dimensional case.Whether it is the spatial correlation of acoustic field or the distribution of acoustic line structure,most of them are analyzed and modeled in the horizontal depth plane.This paper mainly studies the effects of deep-sea mesoscale eddy and shallow water soliton internal wave on the spatial distribution of three-dimensional acoustic field.Firstly,the paper introduces the acoustic speed field model of deep-sea mesoscale eddy and shallow sea soliton internal wave in three-dimensional,and the vertical correlation theory of acoustic field between shallow sea and deep sea.Based on the derivation of two-dimensional parabolic equation method,the acoustic field calculation method of three-dimensional cylindrical coordinate parabolic equation method is improved to successfully calculate the acoustic propagation process under the condition of three-dimensional non-uniform acoustic velocity field;In this paper,the energy distribution of shallow water soliton internal wave in the horizontal direction is analyzed,and the energy distribution in the case of flat seabed and wedge seabed is compared.The effects of three-dimensional soliton internal wave on the vertical correlation of acoustic field,acoustic propagation loss and arrival structure of acoustic line under different acoustic source depths are analyzed;The paper also analyzes the specific effects of deep-sea mesoscale vortices at different locations and types on the energy distribution of the horizontal section of the acoustic field,as well as the vertical correlation of the acoustic field,the length of the correlation characteristics,the arrival structure of the acoustic line,etc.,so as to obtain the different effects of vortices on the generation of convergence area and shadow area;Finally,combined with HYCOM observation data and South China Sea experimental data,the vertical correlation of acoustic field and arrival structure in specific location area are compared and analyzed.The results show that the deep-sea mesoscale vortices have an obvious influence on the position of the convergence area.The cold vortices lead to the convergence area close to the acoustic source,while the warm vortices lead to its distance from the acoustic source,and the mesoscale vortices at different positions in the horizontal direction lead to specific directional changes in the plane acoustic pressure propagation loss;Through the analysis of the influence of soliton internal wave at different positions on the three-dimensional acoustic field on the wedge-shaped seabed,it is found that when the soliton internal wave is located on the upslope of the wedge-shaped seabed,the change of plane acoustic field distribution is more sensitive to the change of frequency.The higher the acoustic source frequency,the clearer the boundary affected by the soliton internal wave.In the depth direction,due to the opposite effect of deep-sea cold eddy and warm eddy on the acoustic line,the vertical correlation appears a specific pattern,and the acoustic line arrival structure changes significantly in advance and delay;The characteristics of vertical correlation of acoustic field at different acoustic source depths are generally weakened by shallow water soliton internal waves.