Earth’s magnetic field reversals from dynamo waves

It is widely believed that the geomagnetic field is created by convection of electrically conducting fluid in the Earth’s molten, metallic core. Simulations of such a huge liquid dynamo machine (rapidly rotating 2300 km thick spherical shell of liquid metal) are computationally extremely demanding. In this four-million CPU-hours simulation physical parameters are as close to the real Earth as computationally feasible. For a very first time a phenomenon called “dynamo wave” has been observed in the Earth’s core scenario, without any further non-physical approximations. A dynamo wave is well known for causing the Sun’s 11-year cycle. In this simulation the dynamo wave causes periodical geomagnetic reversals (magnetic pole swaps).

In the picture: Surfaces of the liquid metal region surrounded by magnetic field lines represent consequent moments of the modeled geomagnetic reversal. The spheres are painted according to values of the radial component of the magnetic field: reds are where magnetic field points out of the Earth’s center, blues – inwards. The field lines are colored according to the direction of the magnetic field. The big sphere is the close up of the surface of the liquid core in the first snapshot.

Full paper: Sheyko, A., Finlay, C. C., Jackson, A. (2016): Magnetic reversals from planetary dynamo waves, Nature, advanced online publication, 07 Nov. 2016, Letter

Video: The Earth’s outer core surrounded by magnetic field lines during the modeled geomagnetic reversal

Image by: Favre, J., Sheyko, A.

Contact: Prof. Dr. Andrew Jackson