Australian Gravity Anomaly Grid with Half Vertical Derivative

Gravity anomaly data measures density variations in subsurface rocks across Australia and its continental margins. The compilation integrates nearly 1.8 million observations, including 1.4 million ground stations and 451,000 line kilometers of airborne gravity and gradiometry surveys collected from the 1940s to 2019. The Australian Ocean Data Network released this processed grid, derived from the 2019 Australian National Gravity Grids B series.

Use Cases

• Map subsurface geological structures by interpreting the half vertical derivative of de-trended global isostatic residual (DGIR) anomalies.
• Model crustal density variations using Complete Bouguer Anomaly (CBA) data corrected for near-field and far-field isostatic effects.
• Enhance resolution in regions with sparse ground data by integrating 345,000 line km of airborne gravity and 106,000 line km of airborne gravity gradiometry surveys.
• Analyze continental-scale geophysical features using a grid with a cell size of 0.00417 degrees (approximately 435m).

Strengths

• Integrates approximately 1.8 million gravity observations from multiple sources.
• Combines ground station data with over 451,000 line kilometers of airborne surveys for improved coverage.
• Grid cell resolution is 0.00417 degrees (approximately 435m).
• Data quality is checked by Geoscience Australia (GA) geophysicists.

Limitations

• Ground station spacing is inconsistent, varying from 11 km to less than 1 km across the continent.
• The temporal range of source data is very wide, from the 1940s to 2019, potentially introducing methodological inconsistencies.
• Specific data formats (APPLICATION/X-NETCDF) may require specialized software for analysis.

Provenance

Source

Australian National Gravity Database (ANGD), Global Gravity grid v28.1 from Scripps Institution of Oceanography/NOAA/NGA, and airborne surveys.

Collection Method

Data processed from ground observations, offshore global grids, and airborne gravity/gravity gradiometry surveys, corrected via isostatic and trend removal and transformed using Fast Fourier Transform (FFT).

Time Range

1940s to 2019

Freshness

Data snapshot is from September 2019, though the record was last updated in April 2026.

Geography

Australia and its continental margins