Geoacoustic Models of the Seabed to Support Range-Dependent Propagation Studies on the Scotian Shelf

Abstract

Joint long-range propagation experiments were performed at two sites in the Western North Atlantic by the Applied Research Laboratory (ARL) of The Pennsylvania State University, and the Defence Research Establishment Atlantic (DREA) of Dartmouth, Nova Scotia. One result of this program was the development of geoacoustic models of the seabed along the propagation tracks between the shallow (ARL) and deep (DREA) receiving arrays. The seabed models are based on profiling performed with the Huntec Deep-Tow System, grab sample data supplied by the Bedford Institute of Oceanography of Dartmouth, Nova Scotia, and dispersion and seismic refraction analysis. Each track is divided into a number of regions, with each region characterized by a geoacoustic model of two to four layers. Compressional wave attenuation values are predicted for each layer, from Huntec and grab sample data, by the Biot-Stoll Sediment model and by historical data. Using the seabed models as inputs to an adiabatic, normal-mode propagation model, transmission loss is predicted and compared with experimental losses measured at the ARL array.