This story is at https://phys.org/news/2022-05-swarm-satellites-unveil-magnetic-outermost.html … ESAs Swarm satellite mission is able to peer down into what is going on inside the earth, from the perspective of electro-magnetism. They say they have found a new type of magnetic wave that sweeps across the outermost reaches of the earth’s core – every seven years. It is not known why it occurs at that interval.
The news emerged in a presentation at ESAs Living Planet Symposium. Earth’s magnetic field is better known as a large bubble that deflects cosmic radiation and charged particles with an origin in the Sun. The magnetosphere is a shield protecting life on earth. However, science is seeking to understand the magnetic field and how it interacts with the solar wind. It is assumed, for many a long year, that earth’s magnetic field is generated by the liquid iron core, acting like a spinning conductor, as in a bicycle dynamo. It generates electrical currents and continuously charges up the electromagnetic field. ESAs Swarm satellites measure these magnetic signals that stem from the earth’s core, as well as various other signals from the crust, the ionosphere, and the magnetosphere. Now, they have found that where the Core meets the Mantle, a mysterious wave oscillates every seven years. Owing to the earth’s rotation these waves align along the axis of rotation. The full paper can be accessed via https://doi.org/10.1073/pnas.2115258119 ..