Identification_Information: Citation: Citation_Information: Originator: NOAA Pacific Island Fisheries Science Center Coral Reef Ecosystem Division Pacific Islands Benthic Habitat Mapping Center Publication_Date: 20070416 Title: Gridded bathymetry of Nihoa Island, Hawaii, USA Geospatial_Data_Presentation_Form: digital data Online_Linkage: http://www.soest.hawaii.edu/pibhmc Description: Abstract: Gridded bathymetry (5m) of the shelf environment of Nihoa Island, Hawaii, USA. The ASCII includes multibeam bathymetry data from the Simrad EM120, Simrad EM1002, Simrad EM300, Simrad EM3002d multibeam sonars collected as of December 2006 by the NOAA Coral Reef Ecosystem Division in depths between 10 and 500 meters. Purpose: The ASCII was created using data gathered from multibeam soundings for use as a planning and reference document. The data are also being used for benthic habitat mapping, for locating Essential Fish Habitat, and for studying geologic features of the area. Refer to supplemental information for description of instrument and survey. Supplemental_Information: Mulibeam data were collected aboard the NOAA Ship Hi’ialakai, a 218’ United States National Oceanographic and Atmospheric Administration research ship. The NOAA Ship Hiialakai's survey sensors include a 30 kHz Simrad EM300 sonar and a 300 kHz Simrad EM3002d sonar, which provide bathymetry and imagery data, a TSS/Applanix POS/MV Model 320, which measures position, velocity, attitude and heading, and a Seabird SBE 9/11 plus CTD used to measure sound velocity profiles. Specific equipment configurations are documented in cruise metadata from the following cruises: HI0501, HI0612. These metadata can be accessed at: http://www.soest.hawaii.edu/pibhmc/pibhmc_cruise-catalog.htm Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 20050404 Ending_Date: 20061029 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: As needed Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -162.393518 East_Bounding_Coordinate: -161.686390 North_Bounding_Coordinate: 23.252926 South_Bounding_Coordinate: 22.887217 Keywords: Theme: Theme_Keyword_Thesaurus: CoRIS Theme Thesaurus Version 1.0 Theme_Keyword: EARTH SCIENCE > Oceans > Bathymetry/Seafloor Topography > Bathymetry Keywords: Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: Bathymetry Theme_Keyword: Multibeam sonar Place: Place_Keyword_Thesaurus: None Place_Keyword: Nihoa Island Place_Keyword: Hawaii Place_Keyword: Northwestern Hawaiian Islands Place_Keyword: United States of America Place: Place_Keyword_Thesaurus: CoRIS Place Thesaurus Version 1.0 Place_Keyword: OCEAN BASIN > Pacific Ocean > Central Pacific Ocean > Hawaiian Islands > Nihoa Island Place_Keyword: COUNTRY/TERRITORY > United States of America > Hawaii > Honolulu Access_Constraints: Use_Constraints: These data are not to be used for navigation purposes. Please acknowledge NOAA and the Joint Institute for Marine and Atmospheric Research (JIMAR) University of Hawaii as the sources of this information. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), NOAA National Marine Fisheries Service (NMFS) Contact_Address: Address_Type: mailing and physical Address: 1680 East-West Road POST 833 City: Honolulu State_or_Province: HI Postal_Code: 96822 Country: USA Contact_Voice_Telephone: 808-956-5239 Contact_Electronic_Mail_Address: pibhmc@soest.hawaii.edu Contact_Instructions: e-mail preferred Browse_Graphic: Browse_Graphic_File_Name: Nihoa_5m.jpg Browse_Graphic_File_Description: Multibeam Bathymetry Browse_Graphic_File_Type: JPEG Data_Set_Credit: PIBHMC, CRED, PIFSC, NOAA and JIMAR Native_Data_Set_Environment: ArcGIS ASCII file created in a LINUX environment Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Data are collected for resource management and research purposes and are tested for internal consistency; however, no effort is made to compare these data to external references or to other published data. Logical_Consistency_Report: These data are believed to be logically consistent though no tests were performed Completeness_Report: Complete Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Horizontal positioning system: Variable, see process description Horizontal position accuracy: Variable, see process description Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: Variable, see process description Raw sounding resolution: Variable, see process description Lineage: Process_Step: Process_Description: Multibeam swath files are acquired in the Generic Sensor Format (GSF) and are edited on a swath by swath basis using SAIC's SABER editing software. The edited swath files are then combined into a Pure File Magic (PFM) format in SABER and area based editing is performed. The edited PFM is then exported as X,Y,Z points with a defined grid cell size. The resulting X,Y,Z data are then gridded using xyz2grd, a Generic Mapping Tools (GMT) algorithm that converts an ASCII or binary table to a netCDF grid file format. GMT is an open source collection of tools for manipulating geographic data sets. Grid nodes with more than one value are set to the average value and unconstrained nodes are set to NaN. Finally, the netCDF grid is clipped at a depth that minimizes data gaps for the specified grid cell size and then converted to an ArcGIS ASCII file format using LINUX/UNIX commands in combination with GMT. Additional information about GMT can be found at: www.soest.hawaii.edu/gmt and additional information about the multibeam data processing is recorded in the cruise metadata. Process_Date: 20070328 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Raster Raster_Object_Information: Raster_Object_Type: Grid Cell Row_Count: 7810 Column_Count: 14344 Vertical_Count: 1 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: Coordinate_Representation: Abscissa_Resolution: 5 Ordinate_Resolution: 5 Planar_Distance_Units: meters Grid_Coordinate_System: Grid_Coordinate_System_Name: Universal Transverse Mercator Universal_Transverse_Mercator: UTM_Zone_Number: 4 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.9996 Longitude_of_Central_Meridian: -159 Latitude_of_Projection_Origin: 0 False_Easting: 500000 False_Northing: 0 Geodetic_Model: Horizontal_Datum_Name: D_WGS_1984 Ellipsoid_Name: WGS_1984 Semi-major_Axis: 6378137.000000 Denominator_of_Flattening_Ratio: 298.257224 Vertical_Coordinate_System_Definition: Depth_System_Definition: Depth_Datum_Name: mean lower low water Depth_Resolution: 0.01 meters Depth_Distance_Units: meters Depth_Encoding_Method: Attribute values Entity_and_Attribute_Information: Overview_Description: Entity_and_Attribute_Overview: Depth values are real values based on the average of the soundings that fell within the extracted grid cells. The number of soundings per grid cell range from >1000 soundings in shallow depths to as few as 20 soundings in deeper areas. A total error budget for this survey has not been developed. Therefore, the accuracy of depth measurements should be considered to be within 1 meter. Entity_and_Attribute_Detail_Citation: none Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), NOAA National Marine Fisheries Service (NMFS) Contact_Address: Address_Type: mailing and physical Address: 1680 East-West Road POST 833 City: Honolulu State_or_Province: HI Postal_Code: 96822 Country: USA Contact_Voice_Telephone: 808-956-5239 Contact_Electronic_Mail_Address: pibhmc@soest.hawaii.edu Contact_Instructions: e-mail preferred Resource_Description: Downloadable Data Distribution_Liability: These data are not to be used for navigational purposes. NOAA makes no warranty regarding these data, expressed or implied, nor does the fact of distribution constitute such a warranty. NOAA cannot assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system. Standard_Order_Process: Digital_Form: Arc ASCII Digital_Transfer_Information: Format_Name: Arc ASCII Format_Information_Content: Arc ASCII can be converted to Arc Raster using ArcToolbox Conversion Tools. Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://www.soest.hawaii.edu/pibhmc Fees: None Metadata_Reference_Information: Metadata_Date: 20070328 Metadata_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), NOAA National Marine Fisheries Service (NMFS) Contact_Address: Address_Type: mailing and physical Address: 1680 East-West Road POST 833 City: Honolulu State_or_Province: HI Postal_Code: 96822 Country: USA Contact_Voice_Telephone: 808-956-5239 Contact_Electronic_Mail_Address: pibhmc@soest.hawaii.edu Contact_Instructions: e-mail preferred Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Time_Convention: Universal Time Metadata_Access_Constraints: None Metadata_Use_Constraints: None