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GDA2020

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GDA2020
NameGDA2020
TypeGeodetic datum
Established2020
RegionAustralia
Epoch2020.0
EllipsoidGRS80
AuthorityGeoscience Australia

GDA2020 is the 2020 realization of the geodetic datum used for spatial referencing across the Commonwealth of Australia. It succeeded earlier national coordinate systems to provide a modernized reference frame aligned with international standards and contemporary satellite geodesy practices. The datum underpins surveying, cadastral mapping, navigation, and geospatial science across agencies including Geoscience Australia, Australian Bureau of Statistics, CSIRO, Airservices Australia, and state land titles offices.

Overview

GDA2020 was instituted to replace legacy systems and to align national coordinates with global reference frames used by International GNSS Service, International Association of Geodesy, International Terrestrial Reference Frame realizations, and services from European Space Agency, National Aeronautics and Space Administration, Japan Aerospace Exploration Agency, and Chinese National Space Administration. The project involved collaboration among federal agencies, state mapping authorities such as Land and Property Information New South Wales, Lands Victoria, Department of Natural Resources and Mines Queensland, and professional bodies including the Surveying and Spatial Sciences Institute and Institution of Surveyors Australia.

Development and Methodology

Development of the datum drew on techniques from space geodesy exemplified by campaigns like IERS Conventions implementations, continuous GNSS networks akin to AuScope, and processing strategies used by SOPAC, IGS Regional Network, and programs operated by European GNSS Agency. Methodology incorporated precise point positioning, network adjustment methods from Least-squares adjustment traditions, and velocity modeling similar to studies by Geoscience Australia and researchers at Australian National University. Reference epoch, realization procedures, and transformation parameters were established following guidelines from International Association of Geodesy, United Nations Committee of Experts on Global Geospatial Information Management, and standards referenced by Open Geospatial Consortium.

Coordinate Frame and Datum Parameters

The coordinate frame adopts an epoch of 2020.0 tied to a fixed, non-rotating realization consistent with epochs used in International Terrestrial Reference Frame releases. Its ellipsoidal parameters reference GRS80 and align with realizations implemented by National Mapping Agency practices. Parameters include plate motion models reflecting motions described by researchers associated with Geoscience Australia and models comparable to those used by US Geological Survey, Natural Resources Canada, and British Geological Survey. Transformation parameters for converting from previous Australian datums were specified to ensure interoperability with systems from Esri, Trimble, Topcon, and mapping products produced by Nearmap.

Adoption and Implementation

Adoption was phased across federal and state agencies, cadastral registries such as Landgate, transport authorities like Austroads, and utilities regulated by Australian Energy Market Operator. Implementation required updates to software used by vendors such as Hexagon AB, Leica Geosystems, and public services like Bureau of Meteorology. Training and guidance were distributed through bodies including Standards Australia, the Surveying and Spatial Sciences Institute, and academic partners at University of Melbourne, University of Sydney, and University of New South Wales.

Differences from Previous Datums

Compared with earlier Australian datums used since the 1990s, the datum introduced a contemporary epoch, refined station coordinates, and explicit velocity terms to address intraplate motion observed in studies from Geoscience Australia and academics at Curtin University. Unlike older realizations tied implicitly to historical survey marks managed by state offices such as Land Victoria and NSW Land Registry Services, the new frame emphasizes a GNSS-centric realization similar to transformations used by European Space Agency missions and NASA geodetic campaigns.

Impact on Mapping and GIS

The datum's release affected base mapping, cadastral accuracy, and geospatial data infrastructures maintained by agencies like Geoscience Australia, Australian Bureau of Statistics, and local councils across municipalities tied to Australian Local Government Association. GIS platforms from Esri, open data initiatives linked to data.gov.au, and commercial imagery providers such as Planet Labs and DigitalGlobe required reprojection and metadata updates. The change improved compatibility with international datasets from OpenStreetMap, Copernicus Programme, and Global Earth Observation System of Systems.

Criticisms and Limitations

Critiques raised by professional groups including the Surveying and Spatial Sciences Institute and academic commentators at Australian National University focused on transitional costs for cadastral continuity, implications for historic survey marks maintained by offices such as Landgate and Land and Property Information New South Wales, and the need for comprehensive training across agencies like Australian Bureau of Statistics and Airservices Australia. Limitations noted include dependencies on continuous GNSS infrastructure like AuScope and susceptibility to updates tied to future International Terrestrial Reference Frame revisions, impacting vendors including Trimble and Leica Geosystems.

Category:Geodetic datums