BPI Structures are derived from two scales of a focal mean
analysis on bathymetry and slope. The grid is based on
gridded (20 m cell size) multibeam bathymetry, collected aboard R/V AHI
and NOAA ship Hi'ialakai. BPI Structures was created using the Benthic
Terrain Modeler (http://www.csc.noaa.gov/products/btm/). Cell values
represent one of 12 classes in an index of seafloor terrains. This data set
is for Baker Island, Pacific Remote Island Areas, Central Pacific.
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 ~150m)
benthic habitats for different organisms that inhabit coral
Gridded multibeam data were 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 and the 218' NOAA Ship Hi'ialakai. The process for deriving the
gridded (20 m cell size) multibeam data is described in baker_20m.asc.txt.
The resulting grid (baker_20m.grd)was used to produce the BPI Structures.
Lundblad et al., 2006, A benthic terrain classification scheme for
American Samoa, Marine Geodesy, 29(2):89 - 111.
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, and the Joint
Institute for Marine and Atmospheric Research (JIMAR) and School
of Ocean and Earth Science and Technology (SOEST), University of
Hawaii as the sources of this information.
NOAA PIFSC CRED PIBHMC, JIMAR, and SOEST
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
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 Structures were derived from the gridded multibeam 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 6 experimental combinations, two scales (100 and 400) best identified fine scale structures for Baker Island while minimizing noise and optimizing possible reef structures (also after Lundblad et al. 2006; see Supplemental_Information). Three ranges of slope define flat, slope, and near vertical: x < 5; 5 < x < 70; x > 70. There may be edge effects at the outer extent of the data.
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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).