Chandler wobble and geomagnetic jerks

Abstract

Some features of the polar motion may be due to core–mantle coupling, but no convincing quantitative mechanism has yet been proposed. Considering phase jumps in the Chandler wobble and noticing their correlation with geomagnetic jerks [J. Geophys. Res. 103 (B11) (1998) 27069–27089], we suggest that the instability of a layer at the top of the core and its downward propagation induce a step in the core–mantle torque strong enough to explain phase jumps in the Chandler wobble. The surface magnetic signature of this instability is comparable with the typical evolution of the geomagnetic field during a jerk.