Joint time-frequency inversion for seabed properties of ship noise on a vertical line array in South China Sea

Geoacoustic inversion is an effective method to obtain the bottom parameters in the deep ocean. This paper proposes a joint time-frequency inversion strategy for bottom surveying from an experiment conducted in the South China Sea in 2016. The seismic-acoustic data of ship noises on a vertical line array are preprocessed for seabed properties. Compared with a controlled source, the inversion using ship self-noise in this paper is ecological and economical. The upward and downward propagation spectrograms at steered angle by beamforming are beneficial in identifying the bottom structure as the prior knowledge for the inversion. The strong tones of ship-radiated noises at frequency bins are useful to correlate the simulated and experimental data and obtain the bottom parameters. A Bayesian method for estimating bottom parameters in the deep ocean is described. The inversion results of multiple layers are validated and showa high confidence, which can explain the transmission loss well along with the experimental track.