Fig. 3: The enhancement of backscattering from a steel spherical shell in the Pekeris waveguide.

a The prescribed incident field for enhancing backscattering from the steel spherical shell in the waveguide (the real part of the pressure), the scattered field due to the prescribed incident field (the real part of the pressure), and the total field when the scatterer is placed at a distance of 500 m (sound pressure level). The magnified plots in (a) display the local region from r = 950 m to r = 1000 m, and the results are given at 215 Hz. b The corresponding total fields when the scatterer is placed at distances of 100 m and 1000 m, respectively. c The total fields resulting from the excitation of Mode 1 and a point source at 215 Hz.