Mantle conductivity

I also proposed that geomagnetic jerks observed at the Earth's surface be interpreted as singularities in the time behavior of the geomagnetic field. Such signals, as they travel from the core through the conducting mantle, should experience some distortion. Assuming the upper mantle acts as an insulator, and taking into account the mantle's electromagnetic time constant and the 2000 km thickness of the uniform lower conductive mantle, I proposed a value for the mantle's electrical conductivity.

Flows at the top of the core

When computing the fluid flow at the CMB over the last four centuries, the flow pattern conserves some broad features over this whole time-span. However, coming to a more accurate description of the last decades, the geometry of the acceleration fields corresponding to the well documented geomagnetic jerks are similar. Furthermore, over the last decade covered by satellite data, I have been interested by the very rapid changes in the magnetic field acceleration, a new source of information on the core flows. I have also shown that connections between geomagnetic jerks detected in the core field acceleration, torsional oscillations and/or core-mantle coupling are important, but I note that all those phenomena must somehow be connected to each other.