Seafloor Characterization using Backscatter Angular Response

Hughes Clarke Danforth and Gardner (USGS)

Funded through USGS and NSERC Research Grant

 

This research has focused on extracting the angular response of backscatter from near-calibrated multibeam sonars as a tool for seabed classification.  Because of the high aspect ratios of multibeam sonars, the variation in backscatter strength from near vertical incidence to lower than 15 degree grazing may be routinely extracted. The variation in backscatter strength over this range of grazing angles has previously been ignored from conventional sidescan backscatter surveys due to their low aspect ratios.

 

This angular response actually makes it harder to interpret conventional backscatter mosaics. The early part of this research actually came out of developing methods to minimize the changes in shape of the angular response. A by-product of this was extracting that signature.  Efforts to correlate the observed angular response with theoretical curves are currently hindered by imperfect data reduction. This is principally a result of:

 

 

At this time the focus is on using empirical methods to attempt field calibration of the residual data artifacts so that the shape of the angular response may be repeatably extracted from sequential surveys.  Most recently a new research thrust has developed to extract this backscatter data from other commonly used sonar systems including NOAA ELAC and RESON systems.