南海深海近海底噪声场垂直空间特性试验研究OA

The vertical spatial characteristics of the ocean ambient noise field in the South China Sea have not yet been clearly clarified,posing challenges for providing accurate guidance for sonar array design,signal processing algorithm optimization,and system performance evaluation.Based on summer near-bottom noise data from a vertical array in the South China Sea,the vertical spatial characteristics of the ocean ambient noise field are analyzed,with key conclusions regarding noise spectrum level,vertical correlation,and directivity as follows:Regarding the noise spectrum level,the 1 000 Hz,1 500 Hz,and 2 000 Hz frequency bands follow a normal distribution,while the 500 Hz band exhibits a chi-square distribution due to external interference;in terms of the vertical correlation of the noise field,the first zero value of the correlation coefficient ranges from 0.4 to 0.75 wavelengths,and when the frequency is less than 1 800 Hz,this zero value exceeds 0.5 wavelengths.Therefore,for a uniform linear array arranged with half-wavelength spacing,the conventional processing gain is lower than the Rayleigh limit under this background noise field;with respect to vertical directivity,the vertical dimension anisotropy affects the processing gain of the vertical array at different depression angles,and a directional trough exists within±15° in the horizontal direction.This is attributed to the fact that noise sources from the sea surface cannot reach the near-bottom receivers at small angles.These results can provide theoretical guidance for the design of sonar arrays and the optimization of signal processing adapted to the deep-sea environment.