Comparison of parabolic equation and adiabatic mode propagation models for matched-field processing in range-dependent environments

Matched-field processing of underwater acoustic array data requires a knowledge of the environment and the use of a suitable propagation model from which field replicas can be computed. For range-dependent environment, parabolic equation or mode-based propagation modelling techniques may be used to provide these replicas. A comparison is presented for environments with sloping bottoms, using the order 3 Pade wide angle approximation for the parabolic equation to ensure precision. The numerical simulations involved generation of `measured´ covariance matrices using PE fields; these were then matched with replicas computed using adiabatic modes. The results showed that for slopes up to 2°, the two techniques yield similar matches, but the adiabatic model provides up to a 100-fold speed advantage