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 U.S. Atlantic continental margin Geospatial_Data_Presentation_Form: ASCII xyb Simrad EM121a data 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. Atlantic continental margin 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: May 1, 2008 Ending_Date: May 31, 2008 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: As needed Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -74.136809 East_Bounding_Coordinate: -67.736162 North_Bounding_Coordinate: 37.724747 South_Bounding_Coordinate: 32.904277 Keywords: Theme: Theme: Theme_Keyword_Thesaurus: Acoustic Backscatter Theme_Keyword: Multibeam Theme_Keyword: Acoustic Backscatter Theme_Keyword: ASCII xyb Theme_Keyword: Continental Slope Place: Place_Keyword: Continental Margin Place_Keyword: Atlantic Margin Place_Keyword: Foot of the Slope Access_Constraints: None Use_Constraints: None Point_of_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 - 6 PM EST Browse_Graphic: Browse_Graphic_File_Name: Browse_Graphic_File_Description: Browse_Graphic_File_Type: Security_Information: Security_Classification: Unclassified Native_Data_Set_Environment: Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: An EM121A 12-kHz multibeam sonar was used with effective beam widths of 1° x 1° (fore-aft x athwart ships) at -3 dB, with swaths of 3.46 times water depth in water depths between 1500 and 4500 m. Depth accuracies determined by cross lines to be better than 0.5% of water depth. 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 Differential-aided DGPS integrated into 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: Depth errors determined by cross lines to be better than 0.5% of water depth. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: Center for Coastal & Ocean Mapping, University of New Hampshire Publication_Date: March, 2009 Title: processed Simrad EM121A datagrams for multibeam backscatter data Type_of_Source_Media: digital Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: March 2009 Source_Currentness_Reference: publication date Process_Step: Process_Description: . Process_Date: May 1 2008-May 31, 2008 Process_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Center for Coastal & Ocean Mapping, University of New Hampshire 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_Electronic_Mail_Address: jim.gardner@unh.edu Hours_of_Service: 9am -5pm Process_Step: Process_Description: Source_Used_Citation_Abbreviation: Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Map_Projection: Map_Projection_Name: unprojected Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: Coordinate_Representation: Abscissa_Resolution: +/- 0.5 meters Ordinate_Resolution: +/- 0.5 meters Planar_Distance_Units: degrees Geodetic_Model: Horizontal_Datum_Name: WGS 84 Ellipsoid_Name: World Geodetic System 84 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: DN 98-bit digital number) Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Attribute: Attribute_Domain_Values: Overview_Description: Entity_and_Attribute_Overview: Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: Center for Coastal & Ocean Mapping, University of New Hampshire Contact_Person: James V. Gardner Resource_Description: Downloadable Data Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: ASCII Winzip compressed Format_Information_Content: Individual soundings of bathymetry in longitude, latitude, depth Transfer_Size: 139.876 MB compressed Digital_Transfer_Option: Offline_Option: Recording_Format: Metadata_Reference_Information: Metadata_Date: March, 2009 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: Address_Type: mailing and physical address Address: Case Ocean Engineering Lab, 24 Colovos Road City: Durham State_or_Province: NH Postal_Code: 3824 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: M-F 9am-5pm Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Time_Convention: local time Metadata_Access_Constraints: None Metadata_Use_Constraints: None Metadata_Security_Information: Metadata_Security_Classification: Unclassified Metadata_Extensions: Online_Linkage: Profile_Name: