Near bottom sediment characterization offshore SW San Clemente Island

Abstract

Absfracf-Normal incidence, 23.5 kHz seafloor acoustic backscatter data and bottom video were measured with the Deep Tow instrument package of the Scripps Institution of Oceanography in 100 meter water depth south of San Clemeute Island, CA. The collected data were processed using an echo envelope sediment characterization method, to derive geoaconstic parameters such as particle mean grain size and the strength of the power law characterizing the roughness energy density spectrum ofthe sediment-water interface. Two regions, sand and silt, were selected based on available ground truth, perceived along-track sediment homogeneity, data quality and tow fish stability. Distinction hehveen s:md and fine grain sediments can he accomplished by Creation of feature vectors comprised of mean grain size (h w and interface roughness spectral strength (w]). Estimates cor mean grain size and roughness spectral strength (M(, w2) were (lS, 0.0095) for sand, and (6.7, 0.0033) for silt, when! M , is expressed in PHI units, and w, has units em4. These results are consistent with local ground truth measurements and illustrate the polential of this sedimenf characterizafiou method in survey mode.'

The Marine Physical Laboratory at Scripps

“…His research has concentrated on using advanced acoustic systems, some of them developed in-house (e.g., Deep Tow), for exploration and study of active deep-sea environments. De Moustier, now at the University of New Hampshire, has been involved in all aspects of swath mapping development and use (Gallaudet and de Moustier, 2001;Stemlicht and de Moustier, 2002). He has used his expertise in sonar engineering and signal processing to make quantitative measurements of seafloor scattering and its relation to surficial structure.…”