Modelling Backscatter at Mid-Frequencies in the Northern Gulf of Mexico


  1. Steele, S.
  2. Pecknold, S.
Corporate Authors
Defence Research and Development Canada, Atlantic Research Centre, Halifax NS (CAN)
In April and May of 2013, a sea trial, the Target and Reverberation Experiment 2013 (TREX13), was undertaken to measure the effect of seabed roughness and composition on reverberation and active sonar performance for mid-frequency sonar, on the order of 1-5 kHz. TREX13 was conducted in an area known as the MAFLA (Mississippi-Alabama-Florida) sand sheet, just off the coast of Panama City, Florida. In this study multiple sources of bathymetry from sonar measurements taken during TREX13 were used to determin roughness spectra of the study area. In situ measurements of geoacoustic parameters taken by a cone penetrometer were combined with the roughness spectra in order to model sediment backscatter, using the composite roughness approximation (CRA). For grazing angles between about 20° and 65° the model shows a similar shape to that predicted by Lambert's Law, using a dimensionless exponenet of μ = −20.2, rather than the standard value of μ = −27. Below 15° the CRA model drops off more quickly compared to Lambert's Law scattering, and above 65° the CRA model predicts much higher backscatter. It is possible that the volume-related backscatter is being underestimed due to volume scattering from volume heterogeneity and discrete scatterers. Evidence from sub-bottom profiler data seems to support that possibility. However, an initial comparison to reverberation data acquired during the trial shows good agreement between the model and data.

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Gulf of Mexico;geoacoustics;reverberation
Report Number
DRDC-RDDC-2017-R151 — Scientific Report
Date of publication
01 Feb 2018
Number of Pages
Electronic Document(PDF)

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