Secousses (jerks) de la variation séculaire et mouvements dans le noyau terrestre

We compute the energy of the flow at the top of the Earth's core taking advantage of the fart that these flows are responsible for the secular variation we observe.It it appears that during the period considered (1840-1990), the energy associated with the non-zonal part of this flow shows strong variations. The rate at which this variation takes place changes suddenly at times geomagnetic jerks are known to have occured. This prompts us to propose that jerks are geomagnetic signatures of changes in the regime of the core flows