Bathymetric Position Index (BPI) Structures 10 m grid derived from gridded bathymetry of Pagan 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 Pagan 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 Pagan Island. As part of the northern islands of the Mariana Islands archipelago, Pagan's offshore terrain has a shelf (above -60m), and a deep shelf (below -60m), with escarpments that lead outside of the coverage area. 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, pagan_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), 20080830, Bathymetric Position Index (BPI) Structures 10 m grid derived from gridded bathymetry of Pagan Island, Commonwealth of the Northern Mariana Islands (CNMI), USA..

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: 145.671
    East_Bounding_Coordinate: 145.848
    North_Bounding_Coordinate: 15.197
    South_Bounding_Coordinate: 14.010
  3. What does it look like?
    http://www.soest.hawaii.edu/pibhmc/CNMI_images/pagan_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 2062 x 1858 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 (~20m 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: 20-Aug-2008 (process 1 of 1)
    Bathymetric Position Index Structures were derived from the gridded multibeam bathymetry (pagan_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 combinations, two scales of bpi (50 & 250) were chosen for Pagan Island. Two fine scale factors (20 and 50) and two broad scale factors (250 and 500) were tested in different combinations. After measuring many of the bathymetric features that indicate possible reef structures when overlaid on the hillshade, initially the values of 500 and 50 were used (also after Lundblad et al. 2006; see Supplemental_Information). However, after running the Benthic Terrain Modeler (BTM), it was apparent that most of the fine scale structures were hard to identify in the classification. Therefore, the other scales of BPI grids were created and used in the Terrain Classification Builder (part of the BTM) to create multiple structure and zone grids. The combination of 20 (or 30) and 250 brought out those fine scale structures, including the broad crests, which are very important in coral reef environments. However, the fine scale factor of 50 defined the fine scale structures as more continuous features and cancelled out a lot of the noise that was falsely defined by using 20 or 30. Additionally, 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 depths were based on the bathymetric drop off on the SW end of the island.
  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: 05-Jun-2019
Last Reviewed: 17-Jul-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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