Echo-signal from a scatterer in an ice-covered homogeneous waveguide

Abstract

The acoustic field scattered from an acoustically rigid or fluid sphere immersed in an ice-covered homogeneous waveguide is modeled. The bottom of the waveguide and the ice cover are specified by their densities and the propagation speeds of longitudinal waves. The scattering coefficients of the sphere are calculated by the normal wave method. The number of normal waves involved in formation of the echo-signal is determined by the preset directivity of the acoustic radiation source. Numerical results are presented for an acoustically rigid scatterer and a scatterer consisting of ice whose properties coincide with those of the ice cover. Two basic models are compared. In the first model, the water layer is bounded from above by an ice half-space and, in the second model, by an air half-space. For these two models, the pressure at the echo-signal reception point is calculated in a wide frequency band of 8–12 kHz.