What is GDA2020?

What is GDA2020?

The Geocentric Datum of Australia 2020 (GDA2020) is a geocentric (earth-centred) coordinate reference system that will soon become Australia’s official national datum. GDA2020 will supersede the existing GDA94 datum and older coordinate systems, such as Australian Geodetic Datum 1966 and 1984 (AGD66 and AGD84).

It is a ‘plate-fixed’ datum that is aligned with the 2014 realisation of the International Terrestrial Reference Frame (or ITRF2014). The “earth-fixed” ITRF is typically not regarded as a “datum” — rather it is the international standard reference framework to which national geocentric datums are aligned.

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GDA2020 coordinates differ from GDA94 coordinates by approximately 1.5 to 1.8 metres and are more closely aligned with the reference frameworks used by modern GNSS — such as GPS, GLONASS, Galileo and BeiDou.

GDA2020 will be defined by coordinates on a selection of Australian geodetic reference stations referred to ITRF2014, at the 1 January 2020 epoch. That is, on January 1 2020, ITRF2014 at epoch 2020.0 will coincide with GDA2020. From 2017 when GDA2020 is established until January 1 2020, the difference between ITRF2014 coordinates at the date of observation (called the observation epoch) and GDA2020 coordinates will continually converge as the Australian tectonic plate moves 7 cm per year in a north-easterly direction. From January 1 2020, there will be an increasing divergence between the coordinates on GDA2020 and ITRF2014.

The legal description of the datum will be effected by replacing the GDA94 locations of the selected geodetic reference stations with GDA2020 locations and issuing a new Legislative Instrument that prescribes the Recognized-Value Standard of Measurement of Position in Australia under the National Measurement Act 1961. The Recognized-Value Standard of Measurement of Position for GDA94 will be repealed.

Approximate shift from GDA94 to GDA2020 locations across Australia.

GDA2020 coordinates can be accessed via spatial connection to the Australian geodetic reference stations with GDA2020 coordinates either:

The standard map projection associated with GDA2020 is the Map Grid of Australia 2020 (MGA2020), a transverse Mercator projection that conforms to the internationally standardised Universal Transverse Mercator Grid system.

More about the Geocentric Datum of Australia