Agenda

Résumé : The complex flow of the liquid iron within the outer core of the Earth is responsible for the geomagnetic field generation, its sustainment and dynamical evolution. Here we consider a turbulent flow in the Earth’s core and the impact of wave interactions on the geomagnetic field evolution. The interactions between waves with distinct but close velocities of propagation (“beating” waves) lead to formation of an electromotive force in the electrically conducting liquid iron inside the core, which slowly varies in time due to the effect of beat. Such an electromotive force generates time‐varying currents and this mechanism can lead to an Earth‐like behaviour of the large‐scale magnetic field, exhibiting long periods of fairly stable field separated by short‐lived reversals or strong excursions (periods of weakened field), which appear to be random. The studied model offers a physical picture of the geomagnetic reversals/excursions based on induction of timevarying currents by wave interactions and allows to pinpoint and understand the relation between the chaotic turbulent flow in the Earth’s core and occurrences of reversals/excursions.