Enhanced 1-meter Composite Grayscale Image of the Sidescan-Sonar Data From National Oceanic and Atmospheric Administration (NOAA) Survey H11079 of the Sea Floor in Great Round Shoal Channel, Offshore Massachusetts (H11079_UTM19_1MRSSS.TIF, UTM Zone 19)

The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration (NOAA) and the Massachusetts Office of Coastal Zone Management (MA CZM), is producing detailed geologic maps of the coastal sea floor. Sidescan-sonar imagery, originally collected by NOAA for charting purposes, provide a fundamental framework for research and management activities along this part of the Massachusetts coastline, show the composition and terrain of the seabed, and provide information on sediment transport and benthic habitat. While acceptable for charting purposes, the original data contained numerous tonal artifacts due to environmental conditions (such as sea state), variable system settings (such as gain changes), attitude variations in the flight path of the towfish, or processing (such as lack of line to line normalization). Many of these artifacts have now been removed by enhancing the imagery to provide a more continuous grayscale GeoTIFF that enhances the true backscatter character and trends of the sea floor.