10 m Gridded bathymetry of Swains Island, American Samoa, South Pacific (Arc ASCII format)

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Frequently anticipated questions:


What does this data set describe?

Title:
10 m Gridded bathymetry of Swains Island, American Samoa, South Pacific (Arc ASCII format)
Abstract:
Gridded (10 m cell size) bathymetry of the slope environment of Swains Island, American Samoa, South Pacific. Almost complete bottom coverage was achieved in depths between 7 and 4800 meters (10 m grid includes data to 300 m). The bathymetry dataset includes Simrad EM300 and Reson 8101ER multibeam data collected from the 10th - 13th of February 2006.
Supplemental_Information:
Data were collected aboard the NOAA Ship Hiialakai, 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. Sensor configuration for the Hi'ialakai for cruise HI-06-02 is documented in the cruise/multibeam metadata file HI0602_MB_Metadata.txt.

Data were also collected aboard the R/V AHI (Acoustic Habitat Investigator), a 25' survey launch owned and operated by the NOAA Pacific Islands Fisheries Science Center in Honolulu, HI. The R/V AHI's survey sensors include a 240 kHz RESON 8101-ER sonar providing bathymetry and imagery data, a TSS/Applanix POS/MV Model 320 which measures position, velocity, attitude and heading, and a Seabird SBE 19 CTD used to measure sound velocity profiles. Sensor configuration for the AHI for cruise AHI-06-02 is documented in the cruise/multibeam metadata file AHI0602_MB_Metadata.txt.

  1. How should this data set be cited?

    Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), 20100701, 10 m Gridded bathymetry of Swains Island, American Samoa, South Pacific (Arc ASCII format).

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -171.218623090848
    East_Bounding_Coordinate: -170.938117186678
    North_Bounding_Coordinate: -10.935484848778
    South_Bounding_Coordinate: -11.188300163771

  3. What does it look like?

    <http://www.soest.hawaii.edu/pibhmc/amsamoa_images/Swains_10m_445.jpg> (JPG)
    Gridded Bathymetry

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 10-Feb-2004
    Ending_Date: 13-Feb-2006
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: raster digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Raster data set. It contains the following raster data types:

      • Dimensions 559 x 697 x 1, type Grid Cell

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: -2
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -171
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000
      False_Northing: 0

      Planar coordinates are encoded using Row and Column
      Abscissae (x-coordinates) are specified to the nearest 10
      Ordinates (y-coordinates) are specified to the nearest 10
      Planar coordinates are specified in meters

      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.

      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: mean lower low water
      Depth_Resolution: 0.01
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute Values

  7. How does the data set describe geographic features?

    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 per cent of water depth.
    Entity_and_Attribute_Detail_Citation: none


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), NOAA and Pacific Islands Benthic Habitat Mapping Center, School of Ocean and Earth Science and Technology, University of Hawaii

  3. To whom should users address questions about the data?

    Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)
    Attn: John Rooney
    NOAA IRC
    Honolulu, HI 96818

    808 725-5360 (voice)
    808 725-5429 (FAX)
    nmfs.pic.credinfo@noaa.gov

    Contact_Instructions: e-mail preferred


Why was the data set created?

The data were collected in support of Coral Reef Conservation Program goals to map all shallow (0-30 m) coral reefs in US Pacific waters and priority moderate (> 30 m) depth areas by 2009. The data are being used to provide bathymetric and backscatter data for previously unmapped areas; in support of ecosystem management requirements for benthic habitat mapping and location of Essential Fish Habitat; and to study the geologic features of the area.


How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: 09-Jun-2010 (process 1 of 1)
    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. The resulting X,Y,Z data are then gridded using nearneighbor, a Generic Mapping Tools (GMT) algorithm that reads arbitrarily located X,Y,Z and assigns an average value to each grid node that has one or more points within a 50 m radius centered on the node and outputs a netCDF grid file. 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 reports AHI0602_MB_Metadata.txt and HI0602_MB_Metadata.txt.

  3. What similar or related data should the user be aware of?


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    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.

  2. How accurate are the geographic locations?

    Horizontal positioning system: GPS C/A Horizontal position accuracy: 25 meters

  3. How accurate are the heights or depths?

    Range resolution of sonar: varies with depth Raw sounding resolution: varies with depth Vertical accuracy of gridded product ~ 1% of water depth

  4. Where are the gaps in the data? What is missing?

    Complete

  5. How consistent are the relationships among the observations, including topology?

    These data are believed to be logically consistent though no tests were performed


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None
Use_Constraints:
These data are not to be used for navigation purposes. Please acknowledge the NOAA Coral Reef Ecosystem Division, Pacific Islands Fisheries Science Center and the Pacific Islands Benthic Habitat Mapping Center, School of Ocean and Earth Science and Technology, University of Hawaii as the sources of this information.

  1. Who distributes the data set? (Distributor 1 of 1)

    Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)
    Attn: John Rooney
    NOAA IRC
    Honolulu, HI 96818

    808 725-5360 (voice)
    808 725-5429 (FAX)
    nmfs.pic.credinfo@noaa.gov

    Contact_Instructions: e-mail preferred
  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    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.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 12-Mar-2014
Last Reviewed: 02-Nov-2010
Metadata author:
Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)
Attn: CRED Data Management Team
NOAA IRC
Honolulu, HI 96818

808 725-5360 (voice)
808 725-5429 (FAX)
nmfs.pic.credinfo@noaa.gov

Contact_Instructions: e-mail preferred
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)


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