Rapid changes in earth’s core affecting magnetic field discovered

The movements in the liquid part of the Earth’s core are changing surprisingly quickly, and this affects the Earth’s magnetic field, according to new research from DTU Space. The Ørsted satellite’s very precise measurements of the Earth’s magnetic field over the past nine years have made it possible for Nils Olsen, Senior Scientist with DTU Space, and several German scientists, to map surprisingly rapid changes in the movements in the Earth’s core. The results have just been published in the scientific journal Nature Geoscience.

Ørsted magnetometer measurements form the base for the latest International Geomagnetic Reference Field, the IGRF2000. A graphical representation of the total magnetic field strength at the Earth's surface inferred from the IGRF2000 is shown below. The blueish-black range of colors represents a field strength above the mean field at the surface and the reddish-yellow range a field strength below the mean field. “What is so surprising is that rapid, almost sudden, changes take place in the Earth’s magnetic field. This suggests that similar sudden changes take place in the movement of the liquid metal deep inside the Earth which is the reason for the Earth’s magnetic field,” Nils Olsen explains. The Earth’s core consists of an inner solid core which is surrounded by an outer liquid core approx. 3,000 km below our feet. Both the liquid core and the solid core consist primarily of iron and nickel, and it is the movements in the outer liquid part of the Earth’s core which create the Earth’s magnetic field. Changes in these movements are seen as changes in the magnetic field, and scientists can therefore use satellite measurements of the magnetic field to find out what is going on in the liquid core deep inside the Earth.

Scientists from DTU Space and other institutions are currently preparing a joint European successor to the Ørsted satellite by the name of Swarm. The Swarm mission consists of three satellites, which will be measuring the Earth’s magnetic field even more accurately than the Ørsted satellite. “By combining the Swarm and Ørsted magnetic measurements we hope to find out the reason for the-se rapid movements in the core,” Nils Olsen concludes. Source: Danish Meteorological Institute/Tech. Inst. of Denmark.

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