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Australian bathymetry and topography grid, June 2005Note: This metadata describes the dataset in accordance with the ANZLIC (Australia New Zealand Land Information Council) Core Metadata Guidelines Version 2. Dataset citationANZLIC unique identifier: ANZCW0703008022 Title: Australian bathymetry and topography grid, June 2005 CustodianCustodian: Geoscience Australia Jurisdiction: Australia DescriptionAbstract: Geoscience Australia and the National Oceans Office carried out a joint venture project to produce a consistent, high-quality 9 arc second (0.0025? or ~250m at the equator) bathymetric data grid of those parts of the Australian water column jurisdiction lying between 92E & 172E and 8S & 60S. As well as the waters adjacent to the continent of Australia and Tasmania, the area selected also covers the area of water column jurisdiction surrounding Macquarie Island, and the Australian Territories of Norfolk Island, Christmas Island, and Cocos (Keeling) Islands. The area selected does not include Australia's marine jurisdiction off of the Territory of Heard and McDonald Islands and the Australian Antarctic Territory. This report provides a list of the datasets and procedures used to produce a grid of 9 arc second cell dimensions. The underlying data from which this grid is derived can only support this resolution in areas where direct bathymetric observations are sufficiently dense (eg. where swath bathymetry data or digitised chart data exist). In areas where only track-line data exist, the grid resolution is high along-line but low perpendicular to lines. In areas where no sounding data are available, the grid is based on interpolated or indirectly observed bathymetry, and these data can only support a resolution of 2 arc minutes (2 nautical miles or ~3.7 km). The grid covers an area of approximately 41 million square kilometres. Its dimensions are 32003 x 20803 cells resulting in a file size slightly in excess of 1.3 Gb of 2-bytes integer numbers representing the bathymetric values. The grid synthesises approximately 1.7 billion observed data points. This grid is not suitable for use as an aid to navigation, or to replace any products produced by the Australian Hydrographic Service. ANZLIC search words:
Spatial domain:
Geographic extent name: AUSTRALIA EXCLUDING EXTERNAL TERRITORIES - AUS - Australia - Australia Geographic extent name: AUSTRALIAN EEZ - AUSTRALIAN EEZ - Ocean and Sea Regions - Australia Geographic extent polygon: 92 -8, 172 -8, 172 -60, 92 -60, 92 -8, Note: The format for each Geographic extent name is: Name - Identifier - Category - Jurisdiction (as appropriate) See GEN Register
Data currencyBeginning date: 2005-04-20 Ending date: 2005-07-28 Dataset statusProgress: Complete Maintenance and update frequency: Not Planned Access
Access constraints: No restrictions Order ProductData qualityLineage: The data came from a variety of systems with differing data densities and levels of accuracy. In the geographic extents 34?N - 79?S, 90?E - 180?E, GA holds approximately 1400 surveys that collected bathymetric data. For ship-track data the typical spacing of point data along track is 25-200m, the two-dimensional spacing of points covered by swath surveys is of similar order. The coverage of ship-track surveys is widely variable, such that some points covered by grid lines are many tens of kilometres apart, whereas for swath bathymetry surveys, the areas of coverage are at relatively high density, but of very limited coverage. This product documents the procedures used to construct the bathymetric grid and their associated displays. The input data were derived from a number of sources, were of variable vintages and quality. A number of approaches were required to process, check and edit the data. The availability of data also varied considerably throughout the region, effectively restricting the maximum useful resolution of the grid in areas where no soundings exist, to that of the satellite predicted bathymetry that was used as infill. These data, together with predicted bathymetry from satellite altimetry, have been brought together into a single data and processing system to allow the routine creation of grids with a range of specifications, from which grids and images can be created. Positional accuracy: The grid incorporates data from surveys acquired since 1963. Modern surveys which used GPS have a positional accuracy of 5 - 30 m depending on several factors, while earlier surveys which used dead reckoning and Transit satellite fixes had positions accurate to 50-2000 m depending upon the water depth and strength of currents. These surveys overlap in an irregular distribution. The grid cell size is 0.025 deg (close to 250m), and it is estimated that 90% of cells give depths within 1 cell of their measured position. Nominal scale: 1:10,000,000 when imaged at 300 dpi Attribute accuracy: All data is in gridded format Logical Consistency: All the grids are chanecked at scale to verify that no data is incorrect, that there were no extraneous point segments, and that all vales have the extimated correct bathymetric contour value. Completeness: This dataset is complete. Contact information
Metadata informationMetadata date: 2008-09-01 Additional metadataMetadata reference XHTML: http://www.ga.gov.au/meta/ANZCW0703008022.html Metadata reference XML: http://www.ga.gov.au/meta/ANZCW0703008022.xml Geomet No. 8022 GeoCat No. 63539 Authors:Webster, M.A Petkovic, P. |
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