Bathymetric Position Index (BPI) Structures 10 m grid derived from gridded bathymetry of Agrihan Island, Commonwealth of the Northern Mariana Islands (CNMI), USA.

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Frequently anticipated questions:


What does this data set describe?

Title:
Bathymetric Position Index (BPI) Structures 10 m grid derived from gridded bathymetry of Agrihan Island, Commonwealth of the Northern Mariana Islands (CNMI), USA.
Abstract:
BPI Structures are derived from two scales of a focal mean analysis on bathymetry and slope. The grid is based on gridded (10 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hi'ialakai and R/V AHI, and it was created using the Benthic Terrain Modeler (http://www.csc.noaa.gov/products/btm/). Cell values represent one of 14 classes in an index of seafloor terrains. This data set is for the shelf and slope environments of Agrihan Island. As part of the northern islands of the Mariana Islands archipelago, Agrihan's offshore shelf, a small area on the south side, is above -60m. A deep shelf (below -60m) is northwest of the island and forms a small plateau. Conversely, the southern islands each have a shelf (above -100m) with escarpments that lead to broad flat areas without forming a deeper shelf.
Supplemental_Information:
Gridded multibeam data were collected aboard the Hi'ialakai, a 218' United States National Oceanographic and Atmospheric Administration (NOAA) research ship, and 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 metadata for the bathymetry is documented in the product metadata, agrihan_10m.txt. (http://www.soest.hawaii.edu/pibhmc/pibhmc_cnmi_bathy.htm) References: Lundblad et al., 2006, A benthic terrain classification scheme for American Samoa, Marine Geodesy, 29(2):89 - 111. http://www.csc.noaa.gov/products/btm/ The terrestrial elevation data shown in the map for this data set are SRTM Finished 3 arc sec Shaded Relief. They were collected during NASA's Shuttle Radar Topograph Mission (SRTM). For more information on the mission, go to: http://www2.jpl.nasa.gov/srtm/faq.html#data. The data are available from the United States Geological Survey (USGS) as reformatted elevation data that are consistent with other Digital Elevation Models.
  1. How might 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), 20090219, Bathymetric Position Index (BPI) Structures 10 m grid derived from gridded bathymetry of Agrihan Island, Commonwealth of the Northern Mariana Islands (CNMI), USA..

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: 145.599
    East_Bounding_Coordinate: 145.721
    North_Bounding_Coordinate: 18.842
    South_Bounding_Coordinate: 18.708
  3. What does it look like?
    http://www.soest.hawaii.edu/pibhmc/CNMI_images/agrihan_10m_BPIstructures_445.jpg (JPG)
    Gridded Bathymetry Derivative
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 25-May-2007
    Ending_Date: 08-Jun-2007
    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 1478 x 1272 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: 55
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: 147
      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.
  7. How does the data set describe geographic features?

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?
    NOAA PIFSC CRED PIBHMC and JIMAR
  3. To whom should users address questions about the data?

Why was the data set created?

The data were derived in support of Coral Reef Conservation Program goals. Goal 1 is to map all U.S. Coral Reef Ecosystems. This data set specifically addresses Objective 1 and 4: to develop high-resolution benthic maps and to characterize priority deep water reefs and associated habitats. This derivative of bathymetry provides a GIS layer that may be used for benthic and essential fish habitat characterization, and for the study of geologic features. By combining the dataset with bathymetry, backscatter, other derivatives, and in situ data, they collectively compose benthic habitat maps which are designed to be used to understand and predict moderate depth (~10m to 800m) benthic habitats for different organisms that inhabit coral reef ecosystems.

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: 04-Feb-2009 (process 1 of 1)
    Bathymetric Position Index Structures were derived from the gridded multibeam bathymetry (agrihan_10m) using the Benthic Terrain Modeler (BTM). The BTM (written for ArcGIS 8.x or 9.x) may be downloaded from http://dusk2.geo.orst.edu/djl/samoa/tools.html. BPI Structures are derived from two scales of a focal mean analysis on bathymetry and slope. After testing multiple scale factors at other northern islands within CNMI and applying them to Agrihan, two scales 50 and 250 best identified fine scale structures for Agrihan Island while minimizing noise and optimizing possible reef structures. In order to promote effective and accurate comparisons of islands, the same scale factors were used for most islands within CNMI and Guam (with only a few exceptions). The Terrain Classification Builder (part of the BTM) was used to create the zone and structure grids. Three ranges of slope define flats, slopes, and near vertical: x < 5; 5 < x < 70; x > 70. Depth bounds separated flat structures into shelf (0 to -60m) and deep shelf (-60 to -1000m) environments. The same depths were used for all of the northern islands within CNMI.
  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 Pacific Islands Fisheries Science Center (PIFSC) Coral Reef Ecosystem Division (CRED) and the Pacific Islands Benthic Habitat Mapping Center (PIBHMC), and the Joint Institute for Marine and Atmospheric Research (JIMAR) 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

    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: 29-Mar-2020
Last Reviewed: 16-Sep-2009
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)
NOAA IRC
Honolulu, HI

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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