A combined noise source model based on vertical coherence to quantify the proportions of two types of noise power.

With the vigorous development of maritime trade, the frequency band from 100 to 1500 Hz of shallow-sea ambient noise is not only affected by surface wind-induced noise but also the contribution of ship noise. Shallow-sea ambient noise can be described by a linear combination of surface wind-induced noise sources and ship noise sources. By using the correspondence between the real part of the vertical coherence and vertical energy flux, this work establishes a combined noise source model based on vertical coherence. A 64-element vertical array is used to measure the ocean ambient noise 103 m deep in an area of the South China Sea. Two scenarios, one dominated by surface wind-induced noise and one dominated by wind-induced noise and ship noise, are selected for investigation. By comparing the theoretical and measured values, the accuracy of the model proposed in this paper and its ability to remove the ship noise reliably are verified. This approach can be used to quantify the proportion of ship noise power in shallow-sea low-frequency environments and evaluate the contributions of wind-induced noise and ship noise at different times.