BPI Zones are derived from a focal mean analysis on bathymetry and slope. The grid is based on gridded (60 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 4 classes in an index of seafloor terrains. This data set is for the shelf and slope environments of Guam Island.
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 to deep depth (~10m to 3500m) benthic habitats for different organisms that inhabit coral reef ecosystems.
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, guam_60m.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.
ground condition
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.
http://www.soest.hawaii.edu/pibhmc/CNMI_images/guam_60m_BPIzones_445.jpg
NOAA PIFSC CRED PIBHMC and JIMAR
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.
These data are believed to be logically consistent though no tests were performed
Complete
Horizontal positioning system: GPS C/A Horizontal position accuracy: 25 meters
Range resolution of sonar: varies with depth Raw sounding resolution: varies with depth Vertical accuracy of gridded product ~ 1% of water depth
Bathymetric Position Index (BPI) Zones were derived from the gridded multibeam bathymetry (guam_60m) 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 Zones are derived from a focal mean analysis on bathymetry and slope. After measuring many of the bathymetric features that indicate possible reef structures when overlaid on the hillshade, initially the values of 1020 and 1800 were tested (also after Lundblad et al. 2006; see Supplemental_Information). After running the Benthic Terrain Modeler (BTM), it was apparent that the features were best identified by using the scalefactor of 1020. Using 1020 instead of 1800 separated features that are not bathymetrically continuous, better defining unique broad scale features. Additionally, two ranges of slope defined flats vs. slopes: x < 5 and 5 > x, respectively.
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NMFS/PIFSC/CRED
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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.
Arc ASCII can be converted to Arc Raster using ArcToolbox Conversion Tools (ASCIItoRaster).
