A theoretical vertical and lateral model for the analysis of acoustic subbottom data through simulation

A high vertical/lateral resolution subbottom survey using a 3‐m paraboloidal reflector operating at 12 kHz in a 1/2‐ms pulsed mode was taken at the University of New Hampshire Ocean Modeling Facility at Lake Winnepeasaukee, New Hampshire. Echograms show a vertical time series composed of several low amplitude single pulsed width signals and several high amplitude unresolvable interacting pulses. The low amplitude pulses are assumed to be reflections from discrete boundaries and the high amplitude unresolvable signal is assumed to indicate a continuous impedance function over depth. A combined discrete and continuous vertical impedance model has been used to simulate the experimental vertical time series. Facsimile graphs taken with the narrow beam show semirandomly positioned reflectors in the sediment column with high definition of subbottom features, while those taken simultaneously over the same cruise track with a wide beam show layers and loss of images. A lateral diffraction model was used to demons...