February 23, 2017207
Australia: A Continent on the Move
Did you know that Australia sits on one of the Earth’s fastest moving tectonic plates and is moving north east by approximately seven centimeters a year? Australian scientists are working on moving Australia’scoordinate reference frame, the Geocentric Datum of Australia 1994 (GDA94) to reflect our actual position in the world. The GDA94 underpins all spatial data and mapping in Australia, and ensures access to the most accurate location-based data available. This is significant when it comes to the use of equipment or spatial data that relies on accurate positioning data.
IGS contributing organisation Geoscience Australia is the Australian Government science body responsible for developing and maintaining the Geocentric Datum of Australia, and ensuring it is of the highest technical quality achievable. As of January 2017, tectonic movement has offset the current Geocentric Datum of Australia 1994 (GDA94) by about 1.6 meters from the International Terrestrial Reference Frame (ITRF). Geoscience Australia is working with state and territory governments and academic institutions to define the new datum, which will be called the Geocentric Datum of Australia 2020 (GDA2020) and will be implemented in 2017.
Using the IGS Network, Products, and Data to Enable Precise Measurements
To best assess changes in the Earth’s surface caused by tectonic forces, crustal deformation is measured daily using precise GNSS data. Geoscience Australia obtains this data from a network of over 600 global and national GNSS stations, including the IGS Network Stations.Geoscience Australia uses a combination of IGS products and data, including regional and Australian GNSS data collected over the last over 20 years and the Bernese GNSS software developed by the Astronomical Institute of the University of Bern (another member of the IGS community), to measure the change in position due to crustal motion. From this information, they are able to derive the new coordinate datum, bringing it into alignment with ITRF2014 at epoch 2020. This new datum will ensure that Australian Spatial data can be used with online digital maps and GNSS positioning which are both ITRF based, ultimately enabling developments such as safe and accurate autonomous vehicles.
In addition to secular tectonic motion, Geoscience Australia also uses IGS network, products and data to measure the internal deformation of the Australian Plate, enabling seismologists to further understand earthquakes within Australia. This is supported by the AuScope GNSS network, which makes an additional 100 GNSS stations accessible to the international geospatial research community – including the IGS. While the AuScope network is not included in the IGS network, the sites are built to comply with IGS site guidelines, ensuring the data from these sites is suitable for use in Earth science research. The information derived from these collaborative efforts will ultimately support the development of improved earthquake and tsunami risk mitigation procedures, as well as updating building codes in Australia.
IGS Antenna Calibration Facility at Geoscience Australia in Canberra
Geoscience Australia’s GNSS antenna calibration facility was built to enable even more accurate measurements of crustal deformation, and to contribute to the global IGS community through the development of better antenna models. These models are required because every antenna, due to manufacturing imperfections, has small biases which can accumulate over time – severely impacting the accuracy of measurements.
By working with the IGS community, especially the IGS Antenna Working Group, as well as cross-comparing calibration analysis results with other facilities globally, Geoscience Australia ensures its results are world-class and provide the best possible antenna resources to the IGS Network.
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