While earthquakes and volcanic eruptions provide vivid evidence that the Earth’s core is anything from calm, there are other, more subtle, dynamic activities occurring far under our feet. Scientists have identified a brand-new kind of magnetic wave that passes across the farthest region of the Earth’s outer core every seven years using data from the ESA’s Swarm satellite project. This intriguing discovery, which was announced today at the ESA’s Living Planet Symposium, provides a new window into a planet we will never be able to view.
The magnetic field of the Earth acts as a sizable bubble that shields us from cosmic radiation and charged particles carried by strong winds that break out of the Sun’s gravitational attraction and travel across the Solar System. Life as we know it would not be possible without our magnetic field.
It is not only of academic interest but also beneficial to society to understand precisely how and where our magnetic field is produced, why it changes continually, how it interacts with solar wind, and, in fact, why it is now deteriorating. While there is little we can do to prevent changes in the magnetic field, being aware of this invisible force allows us to be ready. For instance, solar storms may harm communication networks, navigation systems, and satellites.
The majority of the field is produced by the 3000 km (1900 miles) under our feet ocean of superheated, whirling liquid iron that makes up the Earth’s outer core. It produces electrical currents and the electromagnetic field, which is constantly changing, much like the rotating conductor in a bicycle dynamo.
These magnetic impulses from the Earth’s core as well as other signals from the crust, seas, ionosphere, and magnetosphere are measured by the ESA’s Swarm mission, which consists of three identical spacecraft.
Since the 2013 launch of the three Swarm satellites, researchers have been examining their data to learn more about a variety of Earth’s natural processes, from space weather to the physics and dynamics of the planet’s turbulent core.
The only practical method for exploring far into Earth’s core is to measure our magnetic field from orbit. The material characteristics of the core are revealed by seismology and mineral physics, but the dynamo-generating motion of the liquid outer core is not revealed.
But now, researchers have discovered a hidden secret utilizing information from the Swarm mission.
The discovery of a novel magnetic wave that travels over the’surface’ of the Earth’s outer core, or where the core meets the mantle, is described in a report that was just published in the journal Proceedings of the National Academy of Sciences. Every seven years, this enigmatic wave oscillates and moves westward at a rate of up to 1500 kilometers (900 miles) every year.
Geophysicists have long postulated about the presence of such waves, but they were believed to occur over far longer time scales than our research has indicated, according to lead author Nicolas Gillet of the University Université Grenoble Alpes.
“Instruments located on the surface of the Earth that detect the magnetic field indicated that there may be some sort of wave movement, but we required the worldwide coverage provided by observations from orbit to clarify what is truly happening.
“To explain what the ground-based data had shown, we coupled satellite observations from Swarm with those from the older German Champ mission and Danish rsted mission, together with a computer model of the geodynamo, and this led to our finding,” the authors write.
These waves line up in columns along the axis of rotation because of the rotation of the Earth. Near the equatorial area of the core, the motion and magnetic field changes brought on by these waves are most pronounced.
The existence of such waves that would oscillate at different intervals is still in doubt, even if the research shows magneto-Coriolis waves with a duration close to seven years.
“Magnetic waves are likely to be caused by disturbances deep within the Earth’s fluid core, probably connected to buoyant plumes,” Dr. Gillet continued. Each wave has a period and a typical length scale, and the period varies depending on the properties of the driving forces.
The period of magneto-Coriolis waves is a good indicator of how strong the magnetic field is inside the core. Our findings indicates that further waves of this type are undoubtedly there and possibly have longer durations; however, further study is required to find them.
This study was presented at the ESA’s Living Planet Symposium, which is taking place this week in Bonn, Germany, and is funded by the agency’s Science for Society initiative. Attendees will learn about the most recent scientific studies on Earth as well as how Earth observation from space aids in environmental study and climate change mitigation.
Additionally, they are learning about cutting-edge space technology and the fresh chances opening up in the constantly evolving Earth observation industry. Visit the ESA’s Web TV channels to view the livestreams of several sessions.