Magnetostrophic MRI in the Earth's outer core - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Geophysical Research Letters Year : 2008

Magnetostrophic MRI in the Earth's outer core


We show that a simple, modified version of the Magnetorotational Instability (MRI) can develop in the outer liquid core of the Earth, in the presence of a background shear. It requires either thermal wind, or a primary instability, such as convection, to drive a weak differential rotation within the core. The force balance in the Earth's core is very unlike classical astrophysical applications of the MRI (such as gaseous disks around stars). Here, the weak differential rotation in the Earth core yields an instability by its constructive interaction with the planet's much larger rotation rate. The resulting destabilising mechanism is just strong enough to counteract stabilizing resistive effects, and produce growth on geophysically interesting timescales. We give a simple physical explanation of the instability, and show that it relies on a force balance appropriate to the Earth's core, known as magnetostrophic balance.
Fichier principal
Vignette du fichier
Geophysical Research Letters - 2008 - Petitdemange - Magnetostrophic MRI in the Earth s outer core.pdf (365.82 Ko) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

insu-03603714 , version 1 (10-03-2022)





Ludovic Petitdemange, Emmanuel Dormy, Steven A. Balbus. Magnetostrophic MRI in the Earth's outer core. Geophysical Research Letters, 2008, 35, ⟨10.1029/2008GL034395⟩. ⟨insu-03603714⟩
7 View
10 Download



Gmail Facebook Twitter LinkedIn More