Gridded bathymetry (5m) of the bank environment of parts of the FDM, CNMI USA. These netCDF and ASCII grids includes multibeam bathymetry from the Reson 8101 multibeam sonar aboard the NOAA Ship Oscar E. Sette collected as of May 2010 by the NOAA Coral Reef Ecosystem Division in depths between 10 and 300 meters. These data complement multibeam data collected by the U.S. Naval Oceanographic Office at FDM during several test cruises, which are available from NOAA's National Geophysical Data Center.
These netCDF and ASCII grids were created using data gathered from multibeam soundings for use as a planning and reference document. The data are also being used for benthic habitat mapping, for locating Essential Fish Habitat, and for studying geologic features of the area. Refer to supplemental information for description of instrument and survey.
Multibeam data were collected aboard the NOAA Ship Oscar Elton Sette, a 224' (68 m) United States National Oceanographic and Atmospheric Administration research ship. The NOAA Ship Sette's survey sensors included a 240-kHz pole-mounted Reson 8101ER sonar, which provides bathymetry and imagery data, a TSS/Applanix POS/MV Model 320, which measures position,velocity, attitude and heading, and a Seabird SBE19 CTD used to measure sound velocity profiles. Specific equipment configurations are documented in metadata from cruise SE1002. These metadata can be accessed at: http://www.soest.hawaii.edu/pibhmc/cms/cruise-catalog/
ground condition
These data are not to be used for navigation purposes. Please acknowledge NOAA and the Joint Institute for Marine and Atmospheric Research (JIMAR) University of Hawaii as the sources of this information.
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http://www.soest.hawaii.edu/pibhmc/CNMI_images/FDM_5m_bathy_440.jpg
PIBHMC, CRED, PIFSC, NOAA 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 (SPS) Horizontal position accuracy: 25 m
1 m Raw sounding resolution: Variable
Multibeam swath files are acquired in the Generic Sensor Format (GSF) and are edited on a swath by swath basis using SAIC's SABER editing software. The edited swath files are then combined into a Pure File Magic (PFM) format in SABER and area based editing is performed. During processing it was necessary to change the roll bias parameter in the swath data from +0.13 to -0.1 (determined empirically)in order to reconcile adjoining swaths; this would indicate that the pole-mounted sonar shifted from the original settings determined during a patch test. The edited PFM is then exported as X,Y,Z. The resulting X,Y,Z data are then gridded using xyz2grd, a Generic Mapping Tools (GMT) algorithm that converts an ASCII or binary table to a netCDF grid file format. GMT is an open source collection of tools for manipulating geographic data sets. Grid nodes with more than one value are set to the average value and unconstrained nodes are set to NaN. Finally, the netCDF grid is clipped at a depth that minimizes data gaps for the specified grid cell size and then converted to an ArcGIS ASCII file format using LINUX/UNIX commands in combination with GMT. Additional information about GMT can be found at: www.soest.hawaii.edu/gmt and additional information about the multibeam data processing is recorded in the cruise metadata.
Depth values are real values based on the average of the soundings that fell within the extracted grid cells. The number of soundings per grid cell range from >1000 soundings in shallow depths to as few as 20 soundings in deeper areas. A total error budget for this survey has not been developed. Therefore, the accuracy of depth measurements should be considered to be within 1 meter.
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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.
These data can be downloaded as either a 2-D binary netCDF raster grid or an ArcGIS ASCII text file. The netCDF grid is the default grid file format used by GMT (Generic Mapping Tools), which created this file. More information can be located at http://www.soest.hawaii.edu/gmt/and http://www.unidata.ucar.edu/software/netcdf/. The Arc ASCII file, for use in ESRI's (http://www.esri.com) GIS software, can be converted to an Arc Raster Grid using ArcToolbox ASCII to Raster conversion tool.
