Evaluation of seafloor backscattering strength measured on the Florida continental shelf

Abstract

Recent experiments off the east coast of Florida have measured bottom backscattering strengths for several bottom types at frequencies of 7.5 and 15 kHz. Backscattering strengths are presented as a function of frequency, grazing angle, and azimuthal angle. Coincident with the backscatter measurements, forward scattering measurements and three-dimensional cross-well tomography experiments were conducted to quantify the sediment field. The data and analysis of these are presented in a companion paper given at this conference [Rapids etal., J. Acoust. Soc. Am.]. A newly developed scattering model [Yamamoto, J. Acoust. Soc. Am. (to be published)] has been employed to model the backscattering data. Using the results from the three-dimensional cross-well tomography as input, this model is found to be in good agreement with the data taken. Inversion of the data for sediment descriptors such as aspect ratio, compressional wave velocity fluctuation spectral intensity and spectral exponent, and dip structure has been made, yielding values similar to those obtained wih the insitu measurement by cross-well tomography techniques. These modeling results are detailed in this paper and their significance is discussed. [Work supported by ONR.]