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Enhanced Sidescan-Sonar Imagery, North-Central Long Island Sound

by K.Y. McMullen¹, L.J. Poppe¹, P.T. Schattgen², and E.F. Doran³

Published 2008

Images of sidescan sonar from Long Island Sound.

¹Coastal and Marine Geology Program, U.S. Geological Survey, Woods Hole, MA 02543
²Office of Coast Survey, NOAA, 439 West York Street, Norfolk, VA 23510
³Connecticut Department of Environmental Protection, 79 Elm Street, Hartford, CT 06106


The U.S. Geological Survey, National Oceanic and Atmospheric Administration (NOAA), and Connecticut Department of Environmental Protection have been working cooperatively to map the sea-floor geology within Long Island Sound. Sidescan-sonar imagery collected during three NOAA hydrographic surveys (H11043, H11044, and H11045) was used to interpret the surficial-sediment distribution and sedimentary environments within the Sound. The original sidescan-sonar imagery generated by NOAA was used to evaluate hazards to navigation, which does not require consistent tonal matching throughout the survey. In order to fully utilize these data for geologic interpretation, artifacts within the imagery, primarily due to sidescan-system settings (for example, gain changes), processing techniques (for example, lack of across-track normalization) and environmental noise (for example, sea state), need to be minimized. Sidescan-sonar imagery from surveys H11043, H11044, and H11045 in north-central Long Island Sound was enhanced by matching the grayscale tones between adjacent sidescan-sonar lines to decrease the patchwork effect caused by numerous artifacts and to provide a more coherent sidescan-sonar image for use in geologic interpretation.


The datasets contained in this report have been approved for release and publication by the USGS. Although these datasets have been subjected to rigorous review and are substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, they are released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from their authorized or unauthorized use.

Any use of trade names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Citation: McMullen, K.Y., Poppe, L.J., Schattgen, P.T., and Doran, E.F., 2008, Enhanced Sidescan-Sonar Imagery, North-Central Long Island Sound: U.S. Geological Survey Open-File Report 2008-1174. Also available online at

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