Backscatter from midfrequency (325–1375 Hz) LFM signals at the Mid-Atlantic ridge

Abstract

In July 1993 SACLANTCEN participated in an experiment for the Acoustic Reverberation Special Research Program (ARSRP). The primary objective was to take high-resolution measurements to shed light on the detailed physical processes dominating the low-frequency scattering from rough topographic features and from deep sediment pond areas. A very detailed set of monostatic and bistatic scattering experiments were conducted (using lower frequencies from 200–375 Hz) just west of the Mid-Atlantic Ridge near 26 °N and 47 °W. New results are presented which show higher frequency monostatic scattering from selected bathymetric features using LFM signals. The receivers were horizontal arrays of 128 elements spaced at 0.5, 1, and 2 m. Source/receiver depths were ≊130 and 450 m, respectively. Received reverberation levels are presented as functions of the estimated scatterer position on area bathymetry maps. Inferences for monostatic bottom scattering mechanisms are given using two-way FEPE parabolic equation propagation models from Collins to interpret the data. Some comparisons of measured and modeled reverberation are also presented.