Publication of the new international terrestrial reference system
Zuheir Altamini, head of the team that calculates and publishes the new ITRF benchmark, and a geodesy researcher at IGN and IPGP, talks about the importance of a common international reference that reflects the constant evolution of our planet's surface.
Publication date: 23/05/2022
Press, Research
Related teams :
Geodesy
Related themes : Earth and Planetary Interiors
The Earth is a dynamic planet, whose surface is constantly changing as a result of internal processes, seismic and telluric events and hydrological mass transfers, for example. Knowing the precise position of a point on the Earth’s surface is essential for many everyday applications, such as satellite positioning (GPS), but also for studying and monitoring geological and natural phenomena. To ensure a common reference, the International Astronomical Union and the International Union of Geodesy and Geophysics created the International Earth Rotation and Reference System Service (IERS) in 1988.
This service is currently entrusted to IGN, via the International Terrestrial Reference Frame (ITRF), which is calculated and published by the team led by Zuheir Altamimi, also a geodesist at IPGP.
- What is the purpose of the International Terrestrial Reference Frame?
Zuheir Altimimi: “The ITRF is the norm, or standard reference, recommended by a number of scientific organizations, such as the International Union of Geodesy and Geophysics, for positioning on the Earth’s surface, satellite navigation and Earth science applications.”
- Why is it necessary to recalculate it regularly?
ZA: “The ITRF is materialized and is accessible to users via the time coordinates of more than 1,000 geodetic measuring instruments around the world, most of which observe continuously. As the coordinates evolve over time, it is necessary to update the ITRF (every 5 years or so) in order to improve their accuracy, and thus take into account their variations due to geophysical phenomena, such as earthquakes among others.”
- How is this benchmark used in the various fields of Earth sciences?
ZA: “Geodesy, the metrological component of geophysics, is the science used to quantify the spatio-temporal variations of the three fundamental properties of our planet, namely its shape, its gravitational field and its orientation in space.
The fields of Earth sciences, and their uses of ITRF, are therefore manifold. One of the most emblematic applications is the calculation of altimetry satellite orbits referenced in ITRF. These satellites scan ocean surfaces using radar altimetry to assess spatio-temporal variations in sea level, a major indicator of climate change. Other applications in tectonics or seismology involve exploiting measurements from GNSS/GPS satellites whose orbits and other parameters are referenced in the ITRF.”
Find out more:
- The new version of the International Terrestrial Reference Frame (ITRF2020), published on April 15, 2022, can be accessed via the dedicated website
- See the IGN press release
