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In situ measurement of sediment acoustic properties and relationship to multibeam backscatter

2004; Acoustical Society of America; Volume: 115; Issue: 5_Supplement Linguagem: Inglês

10.1121/1.4780876

1520-9024

Barbara J. Kraft, Luciano Fonseca, Larry A. Mayer, Glenn McGillicuddy, J. Ressler, Jennifer Henderson, Peter G. Simpkin,

Underwater Acoustics Research

In support of the Office of Naval Research’s Geoclutter Program, in situ acoustic and resistivity measurements were obtained using ISSAP, a device developed and built by the Center for Coastal and Ocean Mapping. The primary focus of this research is to understand the relationship between remotely measured backscatter and the acoustic properties of surficial sediments. The field area selected was Portsmouth Harbor (NH) due to the comprehensive sonar data set collected during the Shallow Water Survey 2001 conference. Seawater and surficial sediment measurements of compressional wave sound speed, attenuation, and resistivity were obtained at a large number of stations selected to represent a range of seafloor backscatter types. The ISSAP platform was configured with two orthogonal matched pairs of transducer probes operating at frequencies of 47 and 65 kHz. A Van Veen grab sampler was also used to obtain a sediment sample at each station. Subsampling tubes were used to obtain undisturbed samples; laboratory measurements of density, compressional wave speed and attenuation, resistivity, and grain size were completed. For a small subset of samples, selected to represent a range of sediment types, measurements of permeability, shear wave speed, and attenuation were completed. [Research supported by ONR Grant No. N00014-00-1-0821.]