Long-Range Measurements of Seafloor Reverberation in the Mid-Atlantic Ridge Area

An initial analysis of reverberation measurements made in the Mid Atlantic Ridge area during the Acoustic Reconnaissance Cruise in August 1991 is presented. Sound from a low-frequency source array was scattered by the seafloor at basin-wide ranges and then received by a towed array. Reverberation images show strong returns in the direct-path region followed by returns within concentric bands corresponding to bottom convergence zones. Diffuse and discrete returns occur in both regions. Reverberation images from HFM pulses of differing frequency exhibit similar behavior as do CWs. Discrete features exhibit constant or decreasing relative reverberation level with frequency. Cross-correlation between reverberation beam/time series for different frequency CW subpulses over these features exhibited high but variable correlation throughout the band.