International Terrestrial Reference Frame

As Earth rotates it is continuously in motion in many other ways as well. One of the less known benefits of the age of Global Navigation Satellite Systems (GNSS) has been the ability to support the tracking of ongoing small-scale movements of the overall Earth system through networks of ground-based GNSS stations.

By continuously fixing their position through the use of satnav – supplemented by other space-based methods – these networks reveal slow motion of tectonic plates, glacial rebound, the melting of glaciers and sea level rise, right down to centimetre or millimetre level, and  all essential measurements in the monitoring of climate change dynamics.

In order to plot these tiny shifts in a consistent way, researchers need a frame of reference. The International Terrestrial Reference System is a commonly agreed reference system, which in turn produces the ‘International Terrestrial Reference Frame’, a precise, regularly-updated charting of our planet for the authoritative fixing of coordinates, with axes extending from the ever-shifting centre of mass of the entire planet, including its oceans and atmosphere.

This International Terrestrial Reference Frame is of more than solely scientific interest, being essential to numerous activities, including civil engineering, agriculture and disaster management – even maintaining stable satellite orbits. Indeed the United Nations has recognised improvements in the precision of ‘global geodetic reference frames’ as a sustainable development goal.