Brief description
This grid represents gravity anomalies of the Australian region. The grid combines accurate onshore gravity measurements, with satellite data over the offshore region. The cell values represent simple Bouguer anomalies at a density of 2.67 tonnes per cubic metre onshore and free-air anomalies offshore. The grid cell size is 0.5 minutes of arc, which is equivalent to about 800 metres.Lineage
Maintenance and Update Frequency: continual
Statement: The gravity grid was derived from the complete onshore database as at May 2009 and marine gravity derived from satellite altimetry. A two-pass process was used to generate the grid from a composite file containing 1.4 Million land observations, 10.5 Million satellite values. For the satellite values refer to Sandwell, D.T. and W.H.F.Smith, Marine Gravity Anomaly from Geosat and ERS-1 Altimetry, J. Geophys. Research, 1997. The 0.5 minute grid is the finest mesh that is currently meaningful over the whole continent given that much of the data coverage is spaced at 4 or 11 km.
The parameters of the grid are:
Grid spacing: 0.5 minute = 0.0083333 degree (approx. 800 m)
Projection: Rectangular in latitude and longitude
Grid size: 8401 points longitude x 5276 points latitude
Grid origin: 7 degrees 58.55 min south, 99 deg 57.35 min east (1,1)
Scaling: Nil. Values are in decimal units (µms−² (micro metres per second squared))
Null value: -99999.0
Data accuracy: 5 units, maximum error 100 units onshore
Data precision: 1 unit
Gravity Datum:
The gravity data as supplied are based on the AAGD07 datum. The gravity unit used is micrometres per second squared which is equivalent to 0.1 milligals.
A filtered image was also created using a high-pass filter with a cutoff wavelength of 500 km.
Images have a sunangle with illumination from the north east.
Issued: 2009
text: westlimit=100; southlimit=-52; eastlimit=170; northlimit=-8
Subjects
Earth Sciences |
Geophysics |
Gravimetrics |
Gravity Digital Data |
National dataset |
Non-standard scale |
Published_External |
dataset |
geophysics |
geoscientificInformation |
gravity |
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Other Information
Onshore Bouguer Gravity Geodetic Projection 2009
Onshore Bouguer Gravity Lambert Projection 2009
Onshore Bouguer Offshore Freeair Gravity Geodetic Projection 2009
Onshore Bouguer Offshore Freeair Gravity Lambert Projection 2009
Identifiers
- URI : pid.geoscience.gov.au/dataset/ga/67240
- global : a05f7892-d7b0-7506-e044-00144fdd4fa6
