Geodynamo

The Earth, like many other planetary and astrophysical bodies have intrinsic magnetic fields. All these magnetic bodies share the same essential features: they are rotating rapidly and have a large core of electrically conducting liquid metal in the shape of nearly spherical geometry. Radial buoyancy forces, thermal or compositional, drive convective motions in these liquid cores, which, through magnetic induction, convert the mechanical energy of the fluid motion into the ohmic dissipation of the magnetic field.

To understand the Earth’s magnetism, it is necessary to understand convection and the related magnetohydrodynamic processes taking place in its fluid core. Although numerical geodynamic models which are capable of generating magnetic fields and flows of the right strength and morphology for the Earth have been constructed, the models make controversial use of either hyperviscosity or geophysically unrealistic parameters to produce successful geodynamic solutions.

In the modern era, the problem of magnetohydrodynamic geodynamo is no longer of purely mathematical or theoretical interest. With the rapid advance of supercomputer and AI technology it is now becoming possible to simulate realistic Earth’s dynamos and forecast the changing of the Earth’s magnetic field. Below is a brief description of our progress on the core surface flow inversion.

To obtain the core flow field, we solve the induction equation under the “Frozen Flux” assumption using the physics-informed neural network (PINN). The result of time average core flow field during the year 2000-2019 is shown below.

The core flow changes during the period 2000-2019 is shown in the gif below.