Australia is on the move GDA2020


Recently in the Australian media there has been a lot of commentary around the impending update to Australia’s primary datum. From GDA94 to GDA2020. It has even made the British media http://www.bbc.com/news/technology-36912700.

At Esri Australia this has prompted a lot of questions from clients in regards to the support of the new datum GDA2020 in ArcGIS. Will ArcGIS support GDA2020 and when will ArcGIS support GDA2020?

Before we start to answer these questions I think it is important we understand exactly what the new datum is and why Geoscience Australia is moving towards a new datum.

The current Geocentric Datum of Australia 1994 (GDA1994), the existing national geodetic datum, is not capable of meeting the expectations of a modern technical GPS connected Australia.

The current GDA94 coordinates tell us where things are on the ground in Australia, relative to known Australian fixed reference points. Australia is on a fast moving tectonic plate that moves northwards roughly 7cm a year. The GDA94 coordinates used to locate features and the reference points move along with that plate. Since GDA94 datum was defined, Australia has moved approximately 1.5 metres northwards and so these positions now differ by over 1.5 metres from International Terrestrial Reference Frame (ITRF) coordinates used by Global Navigation Satellite Systems, such as GPS. When referenced by modern GNSS equipment this difference can be important. By 2020 this difference will be approximately 1.8 metres.

To address this, the working group ICSM, has proposed that two national spatial reference frames will be developed.

  • Firstly, there will be a datum that is fixed to the Australian continent, where coordinates do not change with time.
  • The second will be a reference frame that will allow locations of points and their movement over time to be accounted for, accommodating coordinates that can change over time

The following ICSM web page references the implementation time frames for GDA2020. http://www.icsm.gov.au/gda2020/

  • Stage 1 1st January 2017 will deliver a new and more homogenous conventional plate-fixed (or static) datum with the defining coordinates projected forward to a reference date of 1 January 2020.
  • Stage 2 of datum modernisation the Australian Terrestrial Reference Frame (ATRF) will commence implementation in January 2020, and nominally conclude in 2023.

So what about ArcGIS support for GDA2020?

  • It is intended that ArcGIS will support the static datum GDA2020 as soon as practically possible. Esri Australia is in constant contact with Geoscience Australia with regards to the implementation and once the GDA2020 parameters have been made available Esri will endeavour to implement the new datum as soon a practically possible.
  • Esri intends on supporting the dynamic datum due to be released through 2020 and 2023. Esri will be working closely with Geoscience Australia to implement this functionality in its ArcGIS software suite of products.

I hope this helps everyone in the understanding of the new reference datum and the support in the ArcGIS product range. If you have any questions, please do not hesitate to ask.

Gordon

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