The Combined Influence of Wind Waves and Internal Waves on the Coherence of Low-Frequency Acoustic Signals and the Efficiency of Their Spatial Processing in Shallow Water

Abstract

The combined influence of random internal waves and developed wind waves on the coherence and efficiency of spatial processing of narrowband acoustic signals in shallow water is studied analytically and numerically. A theoretical model is proposed for the correlation matrix of a multimode signal at the aperture of a horizontal array, using the difference in the spatiotemporal scales of acoustic field fluctuations caused by wind waves and internal waves. The results of numerical modeling for hydrological conditions in summer are presented. The array gain is analyzed for three spatial processing methods: phased array, optimal linear processing, and optimal quadratic processing. The main focus is on the dependence of the array gain on the intensity of wind waves and distance R between the source and the array. It is shown that, despite summer hydrology, wind waves can have a significant impact on the gain of a horizontal array over a wide range of distances R ~ 10–100 km.