During 2001, Fugro Pelagos, Inc. conducted extensive multibeam echosounder operations in the U.S. waters of the Pacific Ocean, collecting over 15,000 sq km of high-resolution multibeam and backscatter data. Working with Reson, Inc. and Triton Elics, Inc., we added the capability to record the raw backscatter data from each beam for each ping of the Reson 8000 series systems. We refer to this as “snippet”; our proprietary terminology is Footprint Time Series.

Registration of the backscatter data with the across-track bathymetry is based on the intersection of the slant range with the digital seafloor profile. Therefore, the backscatter value is placed at the correct depth on an irregular seafloor. More specifically, the final data product will yield the image pixels precisely located in 3-dimensions, a capability developed by Fugro Pelagos, Inc. to support NOAA-sponsored fisheries habitat and tsunami regional surveys conducted this year.

The multibeam echosounder collects a series of backscatter records across-track for each ping. These backscatter data are mosaicked on the terrain as noted above using pixel size no greater than 0.1% of the water depth per pixel (i.e. 5 cm pixels in 50 meters water depth). The placing of imagery on terrain results in more accurate placement of the acoustic data. Importantly, the hull-mounted transducer offers significant improvements in the positioning of the sonar beams compared to towed sensors. Multibeam bathymetry and backscatter data were acquired and processed to produce a series of products and layers in a GIS environment for further use and analysis.

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Fugro Pelagos conducted a habitat mapping project in a small area south of Kodiak Island, Alaska, using the Research Vessel Davidson fitted with a hull mounted Reson 8111 multibeam echosounder system.