Echo, reverberation and echo to reverberation ratio for isovelocity waveguides related to Weston memorial Workshop scenarios A.2.I and A2.IV

The need for benchmarks of propagation loss was addressed by a series ofworkshops in the 1980s. The main results of those workshops were a set of well-defined propagation scenarios and their corresponding solutions. The availability of these benchmarks permitted the systematic evaluation of the accuracy of propagation models suitable for passive sonar performance prediction. The need for a comparable set of benchmarks suitable for the evaluation of active sonar performance predictions, first recognised internationally in the 2000s, has been addressed in a series of workshops in 2006, 2008 and 2010. The present paper describes some results from the third of these workshops, held in memory of David E. Weston at the University of Cambridge. Results are calculated using discrete normal mode and continuum integration methods, as well as using the active sonar performance models MOCASSIN, ALMOST and LYBIN. Results are presented for echo, reverberation and echo to reverberation ratio from a shaded cosine wave pulse, before and after processing. Scenarios considered include a uniform depth Pekeris waveguide with Lambert rule reverberation (Scenario A2.I) and a generalisation of this problem to an upslope bathymetry (a simplification of Scenario A2.IV)