In 2005 Geoscience Australia and the National Oceans Office undertook a joint project to produce a consistent, high-quality 9 arc second (0.0025° or ~250m at the equator) bathymetric grid for Australian waters. In 2009 a number of new datasets were included in an updated version of the grid.
The 2009 bathymetric grid of Australia has been produced to include recently acquired datasets, and solutions to issues identified in the previous version. The revised grid has the same extents as its 2005 counterpart, including the Australian water column jurisdiction lying between 92° E and 172° E, and 8° S and 60° S. The waters adjacent to the continent of Australia and Tasmania are included, as are areas 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 offshore from the Territory of Heard and McDonald Islands and the Australian Antarctic Territory.
This report details the datasets and procedures used to produce the 2009 bathymetric grid of Australia. As per the 2005 grid, the 0.0025 decimal degree (dd) resolution is only supported where direct bathymetric observations are sufficiently dense (e.g. where swath bathymetry data or digitised chart data exist) (Webster and Petkovic, 2005). In areas where no sounding data are available (in waters off the Australian shelf), the grid is based on the 2 arc minute ETOPO (Smith and Sandwell, 1997) and 1 arc minute ETOPO (Amante and Eakins, 2008) satellite derived bathymetry. The topographic data (on shore data) is based on the revised Australian 0.0025dd topography grid (Geoscience Australia, 2008), the 0.0025dd NZ topography grid (Geographx, 2008) and the 90m SRTM DEM (Jarvis et al, 2008).
The final dataset has been provided in ESRI grid and ER Mapper (ers) formats. An associated shapefile has been produced so that the user can identify the input datasets that were used in the final grid.
This grid is not suitable for use as an aid to navigation, or to replace any products produced by the Australian Hydrographic Service. Geoscience Australia produces the 0.0025dd bathymetric grid of Australia specifically to provide regional and local broad scale context for scientific and industry projects, and public education.
The 0.0025dd grid size is, in many regions of this grid, far in excess of the optimal grid size for some of the input data used. On parts of the continental shelf it may be possible to produce grids at higher resolution, especially where LADS or multibeam surveys exist. However these surveys typically only cover small areas and hence do not warrant the production a regional scale grid at less than 0.0025dd.
There are a number of bathymetric datasets that have not been included in this grid for various reasons. Comments or queries about the data included in the grid (or excluded) can be directed to: IDEASRequests@ga.gov.au.
This grid is not suitable for use as an aid to navigation, or to replace any products produced by the Australian Hydrographic Service.
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 34Â°N - 79Â°S, 90Â°E - 180Â°E, GA holds approximately 1400 surveys that collected bathymetric data.
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.
The Digital Elevation Model (DEM) for New Zealand is based on the 250m DEM data supplied by Geographx, New Zealand (www.geographx.co.nz).
The DEM's for Indonesian and Papua New Guinea are based on the SRTM DEM data supplied by the CGIAR Consortium (srtm.csi.cgiar.org/).
The deep ocean data (where high resolution data were not available) is based on the ETOPO1 and ETOPOV2G data supplied by the National Geophysical Data Center, US Department of Commerce (NGDC) (www.ngdc.noaa.gov/).