A surprise – The Earth has two magnetic fields

Earth's magnetic field, schematic
By Zureks [CC0], from Wikimedia Commons

The satellites belonging to the Swarm project discovered a magnetic field produced by the tides of the oceans. This “new” magnetic field could provide us with better climate change models.

This magnetic field is being produced by ions in the ocean that move along with the tides. The scientists used the Swarm satellites to measure magnetic signals produced by the tides giving them a truly global image of the flow of water at all levels. And because oceans are capable of absorbing pretty big amounts of greenhouse gases this is exactly the kind of information we need if we want to predict how much heat can our oceans absorb.

It's a really tiny magnetic field. It's about 2-2.5 nanotesla at satellite altitude, which is about 20,000 times weaker than the Earth's global magnetic field.

• Nils Olsen

Plus, because the magnetic field produced by the oceans also influences the lithosphere we will soon know more about its electrical properties. The Swarm satellites were released in 2013 and are still collecting more data about Earth’s magnetic fields.

Sources:

• http://www.bbc.com/news/science-environment-43720024
• https://www.esa.int/Our_Activities/Observing_the_Earth/Swarm/Swarm_tracks_elusive_ocean_magnetism