A broadband geoacoustic inversion scheme in shallow water

Abstract

Inversion of modal dispersion curves is an effective method for obtaining underwater acoustic parameters. In this paper, an inversion scheme for synchronously obtaining the sound speed profile and bottom parameters using two wideband explosive sound sources is proposed based on modal dispersion characteristics. First, the first three orders of empirical orthogonal functions were determined and used to invert the sound speed profile. Second, the signal received on a single hydrophone in a vertical line array was decomposed into a series of propagation modes within the frame-work of normal mode theory, and the dispersive characteristics of the modes were analyzed using time-frequency analysis. The warping transform was used to extract the modal dispersion curve. The arrival time differences of the propagation modes were used to invert the environmental parameters. A genetic algorithm was used for the inversion. At last, the reliability of the inversion results was verified by a posteriori probability statistics.