Processed sidescan sonar mosaics (GeoTIFF images) derived from Geoswath multibeam data in Eastern Long Island Sound (2018)

This data set was acquired with a 250 kHz Kongsberg Geoswath Phase Measuring Bathymetry Sonar (PMBS) system mounted in the moon pool of R/V Lowell Weicker. Horizontal accuracy was provided by DGPS augmented by RTK corrections from the Advanced Continuous Operation Reference Network (ACORN). This is a Connecticut statewide system of base stations that provides real-time corrections for GPS equipment operated by the University of Connecticut through a partnership with CTDOT (http://acorn.uconn.edu). Tides were corrected to MLLW based on tide gauge data from NOAA Tide Station at New London, Connecticut (Station ID: 8461490). Sound velocity profiles (SVP) were conducted every three hours to acquire sound speed data using UConn's Valeport SVP system. Data acquisition was performed using the Geoswath+ acquisition software and saved as .rff files for subsequent post-processing. The system recorded bathymetry and sidescan sonar data along with heave, pitch and roll data from a Seatex MRU-5 mounted on the Geoswath transducer. Positional information for all equipment (GPS, transducer, MRU) offsets and latencies can be found in the CARIS vessel file included with the raw data. Line spacing was set at 25 meters for the majority of the survey area with a 30 meter spacing adopted in deeper areas (information provided in the daily Survey Logs). The sidescan sonar data were processed using CARIS software. The data were acquired and processed in two individual blocks. The final sidescan sonar mosaics are in GeoTIFF (Raster) image format, projected in WGS84 UTM 18N (EPSG: 32618) with 1m resolution. The data were collected and assembled as part of the "The Long Island Sound Seafloor Mapping Initiative Phase II – Eastern Long Island Sound" project conducted by the Long Island Sound Mapping and Research Collaborative (LISMaRC, Principal Investigator: Ivar G. Babb). Funding provided by the Long Island Sound Seafloor Mapping Fund administered cooperatively by the EPA Long Island Sound Study and the Connecticut Department of Energy and Environmental Protection (DEEP).