CRED Gridded Bathymetry of Necker Island (100-021) in the Northwestern Hawaiian Islands

File 100-021b is a 60-m ASCII grid of depth data collected near Necker Island in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as part of the "Bathymetric Atlas of the Northwestern Hawaiian Islands -- A Planning Document for Benthic Habitat Mapping -- Draft -- May 2003. Data sources for the downloadable grids include: multibeam bathymetry from Simrad EM1002 and EM120 sonars aboard the R/V Kilo Moana collected in October/November 2003; multibeam bathymetry data from a SeaBeam 210 sonar aboard the R/V Kai'imikai-O-Kanaloa collected in 2000-2002; LIDAR data obtained using the LADS MK II lidar system; and depth data derived from IKONOS satellite imagery. No tidal corrections have been applied to the data. The data source location for each type of data is indicated in the "dot plot" browse objects. Additional single-beam bathymetric data are available in this area and are indicated on the 100-021b Plot C browse object, but these less accurate depths are not included in the downloadable grid. Multibeam data were processed using SABER editing software and MBSystem and multibeam, LIDAR and IKONOS data were integrated using MBSystem, and GMT. Grid spacing is 60-m, horizontal accuracy is 20m (no differential GPS correctors applied), vertical accuracy is depth dependent (~1% of water depth), WGS84 datum. These data are not to be used for navigation.