Metadata: Identification_Information: Citation: Citation_Information: Originator: Center for Coastal & Ocean Mapping, University of New Hampshire Publication_Date: March 2009 Title: ASCII xyb Multibeam Acoustic Backscatter values Data for Gulf of Alaska Description: Abstract: Full coverage, processed multibeam bathymetry acoustic backscatter data - Data were calibrated to the outgoing signal strength, receiver gains, spherical spreading and attenuation and converted from decibel (dB) to 8-bit digital number (DN). The data are provided in a cleaned fully integrated form in ASCII longitude, latitude, backscatter value. Purpose: The National Oceanic and Atmospheric Administration (NOAA), on behalf of the United States Government, has a requirement to carry out surveys of specific regions on the continental margin (slope and rise) in the U.S. Gulf of Alaska in order to obtain multibeam bathymetry. These 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 2000 to 5000 m in order to precisely define the location of the 2500-m isobath and the "foot of the slope" as defined under UNCLOS Article 76. As part of their NOAA-funded research program, University of New Hampshire (UNH) researchers oversaw data acquisition, processing and archiving of the data collected during the cruise. Supplemental_Information: Information about UNH Center for Coastal and Ocean Mapping field activity are online at http://www.jhc.unh.edu/unclos/html/reports.htm. Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 2005 Ending_Date: 2005 Status: Progress: Complete Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -144.600000 East_Bounding_Coordinate: -134.000000 North_Bounding_Coordinate: 60.000000 South_Bounding_Coordinate: 53.750000 Bouding_Coordinate_Units: Decimal Degree Keywords: Theme: Theme_Keyword_Thesaurus: Acoustic Backscatter Theme_Keyword: Multibeam Theme_Keyword: Acoustic Backscatter Theme_Keyword: Continental Slope Place: Place_Keyword: Continental Margin Place_Keyword: Gulf of Alaska Place_Keyword: Foot of the Slope Access_Constraints: None Use_Constraints: Please recognize the University of New Hampshire, Center for Coastal & Ocean Mapping (UNH/CCOM) as the source of this information. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: for Coastal & Ocean Mapping, University of New Hampshire Contact_Person: James V. Gardner Contact_Position: Research Professor Contact_Address: Address_Type: Mailing and Physical Address Address: Chase Ocean Engineering Lab, 24 Colovos Road City: Durham State_or_Province: NH Postal_Code: 03824 Country: USA Contact_Voice_Telephone: 603-862-3473 Contact_Facsimile_Telephone: 603-862-0839 Contact_Electronic_Mail_Address: jim.gardner@unh.edu Hours_of_Service: 9 AM - 5 PM EST Security_Information: Security_Classification: Unclassified Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: A Kongsberg Simrad EM120 12-kHz multibeam sonar was used with effective beam widths no greater than 1° x 1° (fore-aft x athwart ships) at -3 dB, with swaths of 3.4 times water depth in water depths between 1000 and 5000 m, with depth accuracies of the swath of better than ±1% of water depth at these depths. All data meets this specification. Descriptions of the systems and offsets applied can be found within the cruise report at http://www.jhc.unh.edu/unclos/html/reports.htm. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Horizontal positioning of the vessel was determined using a NovAtel OEM2-3151R DGPS integrated with a POS/MV model 320 version 3 system. Positioning is accurate to better than ±5 meters (at 95% confidence) during all surveying. All positioning is referenced to the WGS84 Datum. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: Lineage: Process_Step: Process_Description: Individual acoustic backscatter values were extracted after data cleaning, formatted to ASCII xyb (longitude latitude backscatter) and compressed using WinZip. Process_Date: March 2009 Process_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Center for Coastal & Ocean Mapping, University of New Hampshire Contact_Person: James V. Gardner Contact_Position: Research Professor Contact_Address: Address_Type: Mailing and Physical Address Address: Chase Ocean Engineering Lab, 24 Colovos Road City: Durham State_or_Province: NH Postal_Code: 03824 Country: USA Contact_Voice_Telephone: 603-862-3473 Contact_Facsimile_Telephone: 603-862-0839 Contact_Electronic_Mail_Address: jim.gardner@unh.edu Hours_of_Service: 9 AM - 5 PM EST Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Map_Projection: Map_Projection_Name: Unprojected Geographic Planar_Coordinate_Information: Coordinate_Representation: Abscissa_Resolution: Ordinate_Resolution: Distance_Units: degrees Geodetic_Model: Horizontal_Datum_Name: WGS84 Ellipsoid_Name: WGS84 Semi-major_Axis: Denominator_of_Flattening_Ratio: Vertical_Coordinate_System_Definition: Altitude_System_Definition: Backscatter_Coordinate_System_Definition: 8-bit digital number (DN) Backscatter_Coordinate_System_Definition: DN = 255+(2*DB), where DB is decibel Depth_System_Definition: Depth_Datum_Name: Depth_Resolution: Depth_Distance_Units: Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: Center for Coastal & Ocean Mapping, University of New Hampshire Contact_Person: James V. Gardner Contact_Position: Research Professor Contact_Address: Mailing and Physical Address Address: Chase Ocean Engineering Lab, 24 Colovos Road City: Durham State_or_Province: NH Postal_Code: 03824 Country: USA Contact_Voice_Telephone: 603-862-3473 Contact_Facsimile_Telephone: 603-862-0839 Contact_Electronic_Mail_Address: jim.gardner@unh.edu Hours_of_Service: 9 AM - 5 PM EST Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: ASCII Winzip compressed Format_Information_Content: Individual Beam Acoustic Backscatter Values (longitude, latitude, backscatter) File_Decompression_Technique: Winzip Transfer_Size: 346.65 MB compressed Metadata_Reference_Information: Metadata_Date: 2005 Metadata_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Center for Coastal & Ocean Mapping, University of New Hampshire Contact_Person: James V. Gardner Contact_Position: Research Professor Contact_Address: Mailing and Physical Address Address: Chase Ocean Engineering Lab, 24 Colovos Road City: Durham State_or_Province: NH Postal_Code: 03824 Country: USA Contact_Voice_Telephone: 603-862-3473 Contact_Facsimile_Telephone: 603-862-0839 Contact_Electronic_Mail_Address: jim.gardner@unh.edu Hours_of_Service: 9 AM - 5 PM EST Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Time_Convention: Universal Time Metadata_Security_Information: Metadata_Security_Classification: Unclassified