Direct recovery of wave-penetrable scatterers in a stratified ocean waveguide

We shall derive a direct sampling method for the recovery of wave-penetrable inhomogeneous scatterers in a three-dimensional stratified ocean waveguide. The proposed method is simple, straightforward and computationally efficient since no matrix inversions, optimizations or solutions of ill-posed linear systems are involved. Moreover, it is highly tolerant to noise and is applicable with a few scattered fields corresponding to only two or four incidences. In addition, a priori knowledge of either the number of disconnected components or the physical features of the unknown obstacles is not required by the direct sampling method. A mathematical derivation is provided for its validation and several extensive numerical experiments are shown to evaluate the effectiveness and feasibility of the newly proposed method.