Scattering from under‐ice features and estimation of ice roughness parameters

Abstract

Previous results by Kapoor and Schmidt [J. Acoust. Soc. Am. 93, 2419 (A) (1993)] have shown the possibility of isolating scattering hot spots under the ice sheet by matched‐field processing of short‐range returns assuming point scatterers. A natural extension of this approach is to model the scattered field, or replica field, assuming a more realistic model of the scatterers. Here, examination of the low‐frequency scattering data from the CEAREX 89 field experiments conducted in the Central Arctic region with 1.8‐lb SUS charges detonated at nominal depths of 800 ft is continued. The beamformer outputs from the crossed horizontal array and vertical line arrays are combined simulating a volumetric array, which provides much better resolution of the under‐ice features. The scatterers are modeled as hemispherical and half‐cylindrical protuberances. Importance of elastic properties of the ice and the protuberances will be addressed. Ice roughness parameters are estimated using the method of small perturbations. [Work supported by ONR.]