Long‐range backscatter from the Mid‐Atlantic Ridge

Acoustic backscatter returns measured with a vertical source and horizontal receiving array are beamformed and charted to respective scattering sites on the western flank of the Mid‐Atlantic Ridge (MAR). Well‐defined patterns of high‐level backscatter resembling bottom morphology occur within the direct path and at convergence zone ranges. Measured backscatter is compared with modeled two‐way transmission loss using the wide‐angle parabolic equation (PE) and high‐resolution supporting bathymetry. The level of backscatter is found to be strongly dependent upon two‐way transmission loss (TL). Specifically, TL selects prominent bathymetric features from which high backscatter is returned, with backscatter maxima corresponding to TL minima. Scattering strength estimated for the wide area surveyed shows low variance and relatively minimal spatial variation. Apparently, distinct scattering contributions are so well mixed in long‐range backscatter, that dominant variations are generally due to propagation. These...