Gridded bathymetry and IKONOS estimated depths of the shelf and slope environments of Lisianski Island, Northwestern Hawaiian Islands, Hawaii, USA. Bottom coverage was achieved in depths between 0 and 5000 meters.The ASCII includes multibeam bathymetry from the Simrad EM120, EM1002, EM3002d multibeam sonars collected as of October 2006 by the NOAA Coral Reef Ecosystem Division in depths between 20 and 5000 meters. The ASCII also includes estimated depths derived from high resolution IKONOS satellite imagery by the NOAA/NOS/NCCOS/CCMA Remote Sensing Team in shallow water between 0 and 16 meters.
This ASCII was created using data gathered from multibeam soundings and IKONOS estimated depths 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.
Data were collected aboard the R/V Kilo Moana, a 186' United States Navy owned research vessel. The R/V Kilo Moana's survey sensors include a 12 kHz Simrad EM120 sonar and a 95 kHz Simrad EM1002 sonar, which provide bathymetry and imagery data, a TSS/Applanix POS/MV Model 320, which measures position, velocity, attitude and heading, and a Sippican MK-21/PC based XBT system plus a Seabird SBE 9/11 CTD both of which measured sound velocity profiles. Multibeam data were collected aboard the NOAA Ship Hi'ialakai, a 218' United States National Oceanographic and Atmospheric Administration research ship. The NOAA Ship Hi'ialakai's survey sensors include a 30 kHz Simrad EM300 sonar and a 300 kHz Simrad EM3002d sonar, which provide bathymetry and imagery data, a TSS/Applanix POS/MV Model 320, which measures position, velocity, attitude and heading, and a Seabird SBE 9/11 plus CTD used to measure sound velocity profiles. IKONOS estimated depths were produced using rule-based, semi-automated image analysis of high-resolution satellite imagery for nine locations in the Northwestern Hawaiian Islands. For more information about the estimated depth data see the following online link: http://mercury.ornl.gov/metadata/nbii/html/nos/est%5Fdepth%5Fnwhi.html Specific equipment configurations are documented in metadata from IKONOS Estimated Depths and cruises KM0206, HI0507. 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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NMFS/PIFSC/CRED
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http://www.soest.hawaii.edu/pibhmc/NWHI_images/Lisianski_20m_500.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. The edited PFM is then exported as X,Y,Z points with a defined grid cell size and the points are combined with X,Y,Z IKONOS estimated depth points. 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.
Arc ASCII can be converted to Arc Raster using ArcToolbox Conversion Tools.
