Acoustic backscatter grid from multibeam data collected cruise Kilo Moana KM1811 in the U.S. Gulf of Alaska continental margin


Acoustic backscatter grid from multibeam data ollected on RV Kilo Moana cruise 1811 on the U.S. margin in the Gulf of Alaska, north Pacific Ocean. The National Oceanic and Atmospheric Administration (NOAA), on behalf of the United States Government, has a requirement to carry out mapping surveys of specific regions on the margins in the Gulf of Alaska, north Pacific Ocean in order to determine the detailed bathymetry of the margins. The data are required to support any potential claim for extended jurisdiction by the United States under United Nations Convention on the Law of the Sea (UNCLOS) Article 76. The requirement is for the collection and processing of full-coverage multibeam sonar data in water depths of approximately 1000 to 5500 m in order to precisely define the location of potential natural prolongations to the continent as defined under UNCLOS Article 76. As part of the NOAA-funded research program, University of Hawaii researchers oversaw data acquisition, and University of New Hampshire (UNH) researchers performed the cruise planning and oversaw processing and archiving of the data collected during the cruise. A full patch test was conducted in deep water in the immediate area prior to commencement of mapping. New sound-speed profiles were collected by 139 XBT casts whenever the sound speed at the transducer differed by more than 0.5 m/s. All soundings are within 0.5% (2 sigma) of water depth, based on cross-line checks. Positions were determined by corrected differential GPS-aided inertial navigation. Sound-speed profiles were calculated from an XBT cast calibrated to an XSV cast during a patch test performed on the cruise prior to data collection. Horizontal_Positional_Accuracy_Report: Horizontal positioning of the vessel was determined using Applanix POS/MV inertial motion unit (IMU) version 5 which was provided with wide-area satellite-based differential positioning using the built-in Fugro Marinestar service as well as GNSS G2 service. Positioning is accurate to better than 0.5 meters (at 95% confidence) during all surveying. All positioning is referenced to the WGS84 Datum. Vertical_Positional_Accuracy_Report: Depth errors are within +/-0.5% of water depth. Process_Description: Raw data are as recorded by Kongsberg Maritime SIS data acquisition system. Depth units: meters Reference ellipsoid: WGS-84 Projection: unprojected geographic longitude, latitude Vertical reference: instantaneous sea level. Backscatter data recorded in decibel values (DB) and converted to digital number (DN) using DN=(255+(2*DB)). Decibel values can be retrieved using DB=(DN-255)/2.

Collection Dates:
July 1, 2018
August 3, 2018

Cruise report available at https://dx.doi.org/10.34051/p/2019.2.

Publication Date



Center for Coastal and Ocean Mapping, University of New Hampshire

Digital Object Identifier (DOI)


Grant/Award Number and Agency

National Oceanic and Atmospheric Agency
Office of Ocean Exploration Research

Document Type

Data Set


Cite this data as Miller, Armstrong and Gardner, 2018, Multibeam acoustic backscatter grid from U.S. Law of the Sea ECS cruise KM1811 on the U.S. Gulf of Alaska margin, https://dx.doi.org/10.34051/c/2019.3. Accessed on ddmmyyyy.

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