Horizontal-longnitudinal correlations of low-frequency acoustic field in shallow water

The horizontal-longitudinal correlations of low-frequency acoustic field in shallow water are investigated based on experimental data.The oscillation pattern and strong fluctuations of the horizontal-long-itudinal correlations observed in the experiments are analyzed and interpreted by using the normal modes interference theory.The oscillation pattern is induced by normal modes interference,and the generality of this phenomenon for low-frequency acoustic field in shallow water is further verified by experiments.When the preset depth of the explosive source detonated is close to a node of a valid normal mode′s eigenfunction,small variations of the actual source depths can lead to significant variations of the ratios of the amplitude of that normal mode to the amplitudes of other valid normal modes.Therefore,small variations of the source depths lead to strong fluctuations of the horizontal-longitudinal correlations under the condition that there are relatively small number of valid normal modes in the acoustic field,and the phenomenon show that source depth is a sensitive parameter of the horizontal-longitudinal correlations of low-frequency acoustic field in shallow water under certain conditions.