Brief description
Geoscience Australia and the National Oceans Office carried out a joint venture project to produce a consistent, high-quality 9 arc second (0.0025 degree or ~250 m at the equator) bathymetric data grid of those parts of the Australian water column jurisdiction lying between 92E and 172E and 8S and 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 Australias marine jurisdiction off of the Territory of Heard and McDonald Islands and the Australian Antarctic Territory. The underlying data from which this grid is derived can only support this resolution in areas where direct bathymetric observations are sufficiently dense (e.g. 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. This dataset is a contribution to the CERF Marine Biodiversity Hub and is hosted temporarily by CMAR on behalf of Geoscience Australia.Lineage
Progress Code: completed
Maintenance and Update Frequency: notPlanned
Statement: The data came from a variety of systems with differing data densities and levels of accuracy. In the geographic extents 34N - 79S, 90E - 180E, 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. The initial grid has a spatial resolution of 250 metres. It was resampled to 0.01 DD for CERF project as part of the national datasets.
Notes
CreditWebster
Credit
M.A.
M.A.
Credit
Petkovic
Petkovic
Credit
P. (dataset author)
P. (dataset author)
text: westlimit=92; southlimit=-60; eastlimit=172; northlimit=-8
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Identifiers
- Local : Marlin Record Number: 8820
- global : bc1b3741-e79f-5039-e044-00144f7bc0f4
