On the Determination of Shadow Boundaries and Relevant Eigenrays For Sound Propagation In Stratified Moving Media

The eiconal and ray equations for a stratified moving medium are analyzed to determine which rays connect a source located at an altitude z = z(sub s) to an observer on the ground plane. The characteristics of all available rays are ascertained. Further, the rays which determine the shadow boundary are found. Thus, the shadow boundary may be easily calculated and any observers for which an eigenray does not exist eliminated from further consideration. Therefore, the analysis may be applied to save computer time in two ways. First, rays that do not reach the ground may be eliminated before they are traced, and observers for which no eigenray exists may be eliminated from consideration.