Geo-acoustic parameter estimation using a two-step inversion technique based on normal mode method

The geo-acoustic parameters are of great importance in determining how the sea bottom affects sound propagation in the ocean. Many inversion techniques have been developed to estimate geo-acoustic parameters. One-step inversion algorithms using a cost function defined only by energy loss may not result in a unique solution of geo-acoustic inversion problem because of the correlation between seabed sound speed and attenuation. This paper utilizes different characteristics of normal modes to define appropriate cost functions in a two-step inversion algorithm for inferring geo-acoustic parameters. This inversion scheme is applied to the combustive sound source data obtained by two Lshaped arrays. The inverted seabed sound speed and attenuation are comparable to the results derived from measured time series and transmission loss data at the same experimental site [Knobles, Wilson, Goff, and Cho, J. Acoust. Soc. Am., 124, 2008]. [Work supported by ONR321OA].