A bathymetric Digital Elevation Model (DEM) of the George V and Terre Adelie continental shelf and margin
The various multibeam datasets were processed within acquisition software by the originating agencies in order to correct for sound velocity variations within the water column and the removal of noise. No account has been taken of tidal range, so all depth data is assumed to have a vertical datum of...
| Summary: | The various multibeam datasets were processed within acquisition software by the originating agencies in order to correct for sound velocity variations within the water column and the removal of noise. No account has been taken of tidal range, so all depth data is assumed to have a vertical datum of mean sea-level (MSL). The final DEMs conform to Order 2 of the International Hydrographic Organisation (IHO) Standards for Hydrographic Surveys Special Publication 44 - 5th Edition February 2008. Both Total Horizontal Uncertainty (THU) and Total Vertical Uncertainty (TVU) increase according to depth, so the maximum allowable THU is 30m up to 100m depth, 70m up to 500m depth, 120m up to 1000m depth, 220m up to 2000m depth, and so on. Realistically, however, the accuracy of GPS used for positioning during modern surveys is far better than the maximum allowable THU for Order 2 surveys, and so the THU figures quoted here are very conservative. The maximum allowable TVU is 2.5 m up to 100 m; 11.5 m up to 500 m depth; 23 m up to 1000 m depth; 46 m up to 2000 m depth and so on. This dataset comprises Digital Elevation Models (DEMs) of varying resolutions for the George V and Terre Adelie continental margin, derived by incorporating all available singlebeam and multibeam point depth data into ESRI ArcGIS grids. The purpose was to provide revised DEMs for Census of Antarctic Marine Life (CAML) researchers who required accurate, high-resolution depth models for correlating seabed biota data against the physical environment. The DEM processing method utilised all individual multibeam and singlebeam depth points converted to geographic xyz (long/lat/depth) ASCII files. In addition, an ArcGIS line shapefile of the East Antarctic coastline showing the grounding lines of coastal glaciers and floating ice shelves, was converted to a xyz ASCII file with 0 m as the depth value. Land elevation data utilised the Radarsat Antarctic Mapping Project (RAMP) 200 m DEM data converted to xyz ASCII data. All depth, land and coastline ASCII files were input to Fledermaus 3DEditor visualisation software for removal of noisy data. The cleaned point data were then binned into a gridded surface using Fledermaus DMagic software, resulting in a 0.001-arcdegree (~100 m) resolution DEM with holes where no input data exists. ArcGIS Topogrid software was used to interpolate across the holes to output a full-coverage DEM. ArcGIS was used to produce the additional 0.0025-arcdegree (~250 m) and 0.005-arcdegree (~500 m) resolution grids. Full processing details can be viewed in: Beaman, R.J., O'Brien, P.E., Post, A.L., De Santis, L., 2011. A new high-resolution bathymetry model for the Terre Adelie and George V continental margin, East Antarctica. Antarctic Science 23(1), 95-103. doi:10.1017/S095410201000074X |
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