Slope is derived from gridded (20 m cell size) multibeam bathymetry, collected aboard R/V AHI, and NOAA ship Hi'ialakai. Cell values reflect the maximum rate of change (in degrees) in elevation between neighboring cells derived with the ArcGIS Spatial Analyst extension. This data set is for Baker Island, Pacific Remote Island Areas, Central Pacific.
The data were derived in support of NOAA Coral Reef Conservation Program goals. Goal one is to map all U.S. Coral Reef Ecosystems. This data set specifically addresses Objective one and four: 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 in the slope calculation. Slope was calculated using the slope tool in ESRI ArcGIS Spatial Analyst.
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, 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 IRC
NMFS/PIFSC/CRED
1845 WASP Blvd., Building 176
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http://www.soest.hawaii.edu/pibhmc/PRIAs_images/Baker_20m_slope_445.jpg
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
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
The Spatial Analyst extension was used in ArcMap 9.3 to derive slope from the gridded (20m) bathymetry. Spatial Analyst --> Surface Analysis --> Slope using the following parameters: Input surface: Baker_20m; Output measurement: Degree; Z factor: 1; Output cell size: 20
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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).