Source depth discrimination based on array invariant in shallow water

Waveguide invariant can be used for source depth discrimination in shallow water with a thermocline. However, estimating the value of waveguide invariant is a challenging work if a source is observed by an array without efficient radial aperture. To address the depth discrimination problem for the source with a known distance but no radial distance change relative to the receiving array, an array invariant based method suitable for the shallow water with a thermocline is proposed. In this method, a vertical linear array is used to extract the waveguide invariant based on the array invariant and then the source depth discrimination is realized. The simulation results show that when the vertical linear array is deployed below the thermocline and the source distance is known, the waveguide invariant extracted from the array invariant varies significantly with the source depth and it can be used in source depth discrimination successfully.