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The acquisition of geoacoustic parameters is of great significance to the study of ocean acoustics. On the basis of deducing the seabed reflection coefficient under the layered absorbing medium, analyzes the influence of the absorption coefficient on the seabed reflection coefficient under the condition of large grazing angles. The seabed reflection coefficient oscillates with frequency. When it is equal to the reflection coefficient of the contact interface between seawater and sediment, the anthors define the corresponding frequency point as the 1/4 oscillation period frequency.  At this frequency, the coupling degree between absorption coefficient of sedimentary layer and substrate geoacoustic parameters is less than that of other frequencies. In this paper, the authors propose a stepwise optimization inversion method for deep water geoacoustic parameters based on the seabed reflection characteristics of large grazing angles. Firstly, extracting the interference period of the seabed reflection coefficient by the correlation method, and inverting the sound speed and thickness of the deposited layer by the interference period. The density is obtained from the inversion result of sound speed combined with Hamilton empirical formula. Secondly, calculating the assumed value of the absorption coefficient of the sedimentary layer by combining the search boundary of the substrate sound speed, using the substrate reflection coefficient at 1/4 oscillation period frequency to realize the one-dimensional inversion of the substrate sound speed. Finally, using the seabed reflection coefficient at the half-wave layer frequency to realize the one-dimensional inversion of the absorption coefficient of the sedimentary layer. The seabed reflection characteristics of large glancing angles combined with stepwise inversion to reduce the coupling degree of the substrate sound speed and the absorption coefficient of the sedimentary layer. Experimental results show that the geoacoustic parameters retrieved by this method can be effectively applied to propagation loss prediction in a certain range under the condition of large grazing angle measurement.

Inversion of deep water geoacoustic parameters based on the seabed reflection characteristics of large grazing angles