Measurement, Characterization, and Modeling of Ice and Bottom Backscattering and Reverberation in the Arctic Ocean

Abstract

Acoustic reverberation data from SUS explosions collected during the CEAREX 89 Arctic experiment are analyzed to estimate both under-ice and bottom backscattering strengths at very low frequencies (below 50 Hz). Short range direct-path returns are analyzed to measure the backward scattering strengths of the under-ice surface for scattering angles between 2.5° and 40° grazing and frequencies between 24 Hz and 105 Hz. Medium range (5–20 km) ice and bottom reverberation returns received on a 1200-m vertical array are separated using the time-arrival angle relationship to measure ice and bottom backscattering strengths at 23 Hz for grazing angles of 15°–60°. Long range reverberation is modeled by combining a normal-mode based scattering description with grazing angle dependent scattering functions based on small-ka (low frequency) approximations. Reverberation data at 23 Hz are successfully modeled for four cases of different bottom bathymetry and source depth.