BPI Zones are derived from gridded (20 m cell size) multibeam
bathymetry, collected aboard R/V AHI and NOAA ship Hi'ialakai.
BPI Zones was created using the Benthic Terrain Modeler (http://www.csc.noaa.gov/products/btm/).
Cell values represent one of 4 classes (crest, depression, slope, flat) in an index of seafloor terrains.
This data set is for Swains Island, American Samoa.
The data were derived in support of NOAA 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 - 150m) benthic habitats for different
organisms that inhabit coral reef ecosystems.
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 Zones.
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.
1845 WASP Blvd., Building 176
NOAA PIFSC CRED and the Pacific Islands Benthic Habitat Mapping Center, 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 Zones were derived from the gridded multibeam bathymetry (baker_20m) 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 testing 3 different scalefactors, a scalefactor of 400 was chosen as best identifying broad scale zones for Baker Island while minimizing noise and optimizing possible reef structures (also after Lundblad et al. 2006; see Supplemental_Information). Two ranges of slope define flat, and slope: x < 5; and x > 5. There may be edge effects at the outer extent of the data.
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).