Understanding the origin of the magnetic field, why it fluctuates constantly, how it interacts with the solar wind, and in fact why it is currently weakening, all of these questions are topics of interest to scientists. Most of the magnetic field is generated by an overheated and swirling liquid iron ocean that forms the outer core of the Earth. The outer core of the Earth acts as a driver rotating on a bicycle dynamo. It generates electric currents and a constantly changing electromagnetic field.
ESA’s Swarm mission, which consists of three identical satellites, measures these magnetic signals from the Earth’s core. It also measures other signals from the crust, oceans, ionosphere, and magnetosphere.
Using data from the Swarm mission, scientists have uncovered a hidden secret. They have detected a new type of magnetic wave that sweeps the “surface” of the Earth’s outer core. What’s more interesting is that this wave oscillates every seven years and propagates westward up to 1500 miles a year.
These waves line up in columns along the axis of rotation due to the rotation of the Earth. The changes in motion and magnetic field caused by these waves are more pronounced in the equatorial region of the core.
Although research shows magneto-Coriolis waves in seven years, it has not yet been answered whether these waves exist at different intervals.
Nicolas Gillet, University of Grenoble Alpes and lead author of the article, said: “Geophysicists have long theorized about the existence of these waves, but they were thought to take place on much longer time scales. longer than our research has shown. “
“Magnetic field measurements of instruments based on the Earth’s surface suggested that there was some wave action, but we needed the global coverage that measurements offer from space to reveal what’s going on.” .
“We combined satellite measurements from Swarm and the previous German mission and the Danish Ørsted mission with a geodynamic computer model to explain what the terrestrial data had generated, which led to our discovery.”
“Magnetic waves are likely to be triggered by perturbations in the depths of the Earth’s fluid core, possibly related to buoyancy plumes. Each wave is specified by its typical period and length scale, and the period depends on the characteristics of forces For magneto-Coriolis waves, the period is indicative of the intensity of the magnetic field within the nucleus.
“Our research suggests that other such waves are likely to exist, probably with longer periods, but their discovery is based on further research.”
ESA Swarm Mission scientist Ilias Daras noted: “This current research will undoubtedly improve the scientific model of the magnetic field within the Earth’s outer core. It can also give us a new view of the electrical conductivity of the lowest part of the mantle and also of the thermal history of the Earth “.
Magazine reference:
- Nicolas Gillet et al. Magnetic data from satellites reveal interannual waves in the Earth’s core. DOI: 10.1073 / pnas.2115258119