Skip to Main content Skip to Navigation
New interface
Journal articles

Magnetostrophic MRI in the Earth's outer core

Abstract : 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.
Document type :
Journal articles
Complete list of metadata
Contributor : Nathalie POTHIER Connect in order to contact the contributor
Submitted on : Thursday, March 10, 2022 - 2:26:24 PM
Last modification on : Friday, October 21, 2022 - 3:32:40 PM


Geophysical Research Letters -...
Publisher files allowed on an open archive





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⟩



Record views


Files downloads