Authors / CoAuthors
Geophysical Acquisition & Processing Section
Abstract
Gravity data measures small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This National Gravity Compilation 2019 includes airborne (free air grid) is a free air anomaly grid for the 2019 Australian National Gravity Grids B series. This gravity survey was acquired under the project No. 202008. This gravity anomaly grid is derived from ground observations stored in the Australian National Gravity Database (ANGD) as at September 2019, supplemented with offshore data sourced from v28.1 of the Global Gravity grid developed using data from the Scripps Institution of Oceanography, the National Oceanic and Atmospheric Administration (NOAA), and National Geospatial-Intelligence Agency (NGA) at Scripps Institution of Oceanography, University of California San Diego. Airborne gravity and gravity gradiometry data were also included to provide better resolution to areas where ground gravity data was not of a suitable quality. Out of the approximately 1.8 million gravity observations, nearly 1.4 million gravity stations in the ANGD together with Airborne Gravity surveys totaling 345,000 line km and 106,000 line km of Airborne Gravity Gradiometry were used to generate this grid. The grid shows free air gravity anomalies over Australia and its continental margins. The ground and airborne gravity data used in this grid has been acquired by the Commonwealth, State and Territory Governments, the mining and exploration industry, universities and research organisations from the 1940's to the present day. Station spacing varies from approximately 11 km down to less than 1 km, with major parts of the continent having station spacing between 2.5 and 7 km. Airborne surveys have a line spacing ranging from 0.5 km to 2.5 km. The grid has a cell size of 0.00417 degrees (approximately 435m). The data are given in units of um/s^2, also known as 'gravity units', or gu.
Product Type
dataset
eCat Id
144773
Contact for the resource
Point of contact
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
- theme.ANZRC Fields of Research.rdf
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- EARTH SCIENCES
- ( Data centre )
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- NCI
- ( Discipline )
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- Earth sciences
- ( Discipline )
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- geophysics
- ( Feature type )
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- grid
- ( Place )
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- Australia
- ( Place )
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- None
- ( Project )
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- survey 202008
- ( Theme )
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- GADDS2.0
- ( Theme )
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- gravity
- ( Theme )
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- free air
- ( Theme )
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- ground digital data
- ( Theme )
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- geophysical survey
- ( Theme )
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- grav
- ( Theme )
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- grid
- ( Theme )
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- raster
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- Published_External
Publication Date
2020-10-31T00:00:00
Creation Date
2020-10-31T00:00:00
Security Constraints
Legal Constraints
Status
completed
Purpose
Maintenance Information
notPlanned
Topic Category
geoscientificInformation
Series Information
Lineage
This National Gravity Compilation 2019 includes airborne (free air grid) is a free air gravity anomaly grid for the 2019 Australian National Gravity Grids B series. This gravity survey was acquired under the project No. 202008. This gravity anomaly grid is derived from ground observations stored in the Australian National Gravity Database (ANGD) as at September 2019, supplemented with offshore data sourced from v28.1 of the Global Gravity grid developed using data from the Scripps Institution of Oceanography, the National Oceanic and Atmospheric Administration (NOAA), and National Geospatial-Intelligence Agency (NGA) at Scripps Institution of Oceanography, University of California San Diego. Airborne gravity and gravity gradiometry data were also included to provide better resolution to areas where ground gravity data was not of a suitable quality. Out of the approximately 1.8 million gravity observations, nearly 1.4 million gravity stations in the ANGD together with Airborne Gravity surveys totaling 345,000 line km and 106,000 line km of Airborne Gravity Gradiometry were used to generate this grid. The ground and airborne gravity data used in this grid has been acquired by the Commonwealth, State and Territory Governments, the mining and exploration industry, universities and research organisations from the 1940's to the present day. Station spacing varies from approximately 11 km down to less than 1 km, with major parts of the continent having station spacing between 2.5 and 7 km. Airborne surveys have a line spacing ranging from 0.5 km to 2.5 km. The free air gravity anomalies were calculated after applying a free air correction to the measured gravity anomaly, to correct for the change in gravity due to the difference in elevation of the gravity station relative to datum elevation, usually mean sea level. The data were then gridded using a gridding technique provided by the INTREPID Geophysics software package. The grid shows free air gravity anomalies over Australia and its continental margins. The grid has a cell size of 0.00417 degrees (approximately 435m). The data are given in units of um/s^2, also known as 'gravity units', or gu. The processed data are checked by GA geophysicists using standard methods for assessing quality to ensure that the final data are fit-for-purpose. Details of the specifications of individual surveys held in the Australian National Gravity Database (ANGD) can be found in the Second Edition of the Index of Gravity Surveys (Wynne and Bacchin, 2009). References Intrepid Geophysics. http://www.intrepid-geophysics.com. Wynne, P., and Bacchin, M., 2009. Index of Gravity Surveys (Second Edition). Geoscience Australia, Record 2009/07.
Parent Information
Geophysical Data Collection - gravity
UUID - c6b58f54-102c-19e9-e044-00144fdd4fa6,
eCat ID - 74512
Extents
[-48.0021, -7.9979, 107.9979, 164.0021]
Reference System
GDA94 (EPSG:4283)
Spatial Resolution
Service Information
Associations
Downloads and Links
File available for download in various formats from the GADDS2 portal
/g/data/iv65/Geoscience_Australia_Geophysics_Reference_Data_Collection/national_geophysical_compilations/Gravmap2019/Gravmap2019-grid-grv_fa-IncludesAirborne.nc file at NCI
/g/data/iv65/Geoscience_Australia_Geophysics_Reference_Data_Collection/national_geophysical_compilations/Gravmap2019/Gravmap2019-grid-grv_fa-IncludesAirborne.nc file download
Source Information
This National Gravity Compilation 2019 includes airborne (free air grid) includes ground, satellite marine, airborne gravity and gradiometry data for the 2019 Australian National Gravity Grids B series.