A simulation model for high‐frequency under‐ice acoustic backscattering

Abstract

A model has been developed to evaluate the backscattering of a high‐frequency acoustic pulse from the pack ice regions characteristic of the interior Arctic. The model utilizes measured two‐dimensional under‐ice profile data and several empirical results that relate the morphological parameters of the large under‐ice scattering features called ice keels, to construct a three‐dimensional bimodal under‐ice canopy consisting of first‐year ice keels and flat ice regions. A first‐year ice keel is modeled as an ensemble of randomly oriented ice blocks on a planar surface inclined at some slope angle with respect to the plane of the ice‐sea water interface. The keel is further characterized by length, draft, width, ice thickness, and aspect angle. A region of flat ice is modeled as a smooth planar surface whose slope angle is less than some critical angle that serves to distinguish a flat ice region from an ice keel. The Kirchoff approximation is used to evaluate the scattering strength of an individual ice bloc...