Scenarios for Benchmarking Range-Dependent Active Sonar Performance Models

A set of eight sonar problems, pertaining to man-made active sonar, with source frequencies ranging from 250 Hz to 3.5 kHz, is defined. The scenarios are designed to emphasize range dependent propagation aspects in coastal waters, with the aim of testing all terms of the sonar equation (except the detection threshold) both before and after signal processing, including beamforming and matched filtering. The starting point is a range-independent baseline problem, which is a generalization of the Second ONR Reverberation Modeling Workshop problem ‘T’. This problem is successively made more complex by adding surface roughness, summer and winter sound speed profiles, deforming the bathymetry into an upslope and a downslope propagation scenario, and by considering the presence of a solitary wave in the water column of the uniform water depth problem. The capability of modelling sub-bottom rough scattering layers and ship noise is also tested in two range-independent problems. A subset of initial results from a first round of comparisons between computations carried out by the participants of the David Weston Memorial Symposium on the Validation of Sonar Performance Assessment Tools, held in Cambridge on 7 – 9 April 2010, is presented.