Electromagnetically driven westward drift and inner-core superrotation in Earth’s core

  title={Electromagnetically driven westward drift and inner-core superrotation in Earth’s core},
  author={Philip W. Livermore and Rainer Hollerbach and Andrew Jackson},
  journal={Proceedings of the National Academy of Sciences},
  pages={15914 - 15918}
Significance Seismic probing of the earth’s deep interior has shown that the inner core, the solid core of our planet, rotates slightly faster (i.e., eastward) than the rest of the earth. Quite independently, observations of the geomagnetic field provide evidence of westward-drifting features at the edge of the liquid outer core. This paper describes a computer model that suggests that the geomagnetic field itself may provide a link between them: The associated electromagnetic torque currently… 

Figures from this paper

An accelerating high-latitude jet in Earth’s core
Observations of the change in Earth’s magnetic field—the secular variation—provide information about the motion of liquid metal within the core that is responsible for the magnetic field’s
Geophysical implications of a decentered inner core
In a first approximation, the Earth's interior has an isotropic structure with a spherical symmetry. Over the last decades the geophysical observations have revealed, at different spatial scales, the
Local Estimation of the Earth's Core Magnetic Field
The geomagnetic field is generated in the Earth’s outer core by fluid motions in a process known as the geodynamo. During the past 18 years satellite magnetic measurements have provided new insights
Superrotation of Earth’s Inner Core, Extraterrestrial Impacts, and the Effective Viscosity of Outer Core
The recently verified superrotation of Earth’s inner core is examined and a new model is presented which is based on the tidal despinning of the mantle and the viscosity of the outer core. The model
Complex inner core of the Earth: The last frontier of global seismology
The days when the Earth's inner core (IC) was viewed as a homogeneous solid sphere surrounded by the liquid outer core (OC) are now behind us. Due to a limited number of data sampling the IC and a
Turbulent geodynamo simulations: a leap towards Earth's core
We present an attempt to reach realistic turbulent regime in direct numerical simulations of the geodynamo. We rely on a sequence of three convection-driven simulations in a rapidly rotating
Characterizing convection in geophysical dynamo systems
The Earth’s magnetic field is produced by a fluid dynamo in the molten iron outer core. This geodynamo is driven by fluid motions induced by thermal and chemical convection and strongly influenced by
Geomagnetic polar minima do not arise from steady meridional circulation
It is shown that the change in polar magnetic field resulting from steady, large-scale meridional circulations in Earth’s outer core is less than 3% of the background field, significantly smaller than the ∼ 100% polar magnetic minima observed at the CMB.
Torsional Alfvén waves in the Earth's core
Torsional Alfven waves are theoretically predicted to exist in Earth's outer core, have been inferred from geophysical data and observed in geodynamo simulations. They provide an indirect means of


Westward drift, core motions and exchanges of angular momentum between core and mantle
The westward drift is one of the most well known features of the geomagnetic field. In this paper we come back to the apparent drift of the main field as seen at the Earth's surface, and show that
Lopsided Growth of Earth's Inner Core
It is proposed that the growth of the solid core implies an eastward drift of the material, driven by crystallization in the Western Hemisphere and melting in the Eastern Hemisphere, which generates an asymmetric distribution of sizes of iron crystals, which grow during their translation.
Geodynamic estimates of the viscosity of the Earth's inner core
Recent seismological studies, have suggested that the inner core is rotating relative to the bulk of the Earth, a situation which (according to numerical simulations) may be sustained by convective
Inner core–mantle gravitational locking and the super-rotation of the inner core
SUMMARY Seismological observations suggest that the Earth’s solid inner core has been rotating faster than the mantle over the past several decades, consistent with the results of some numerical
Fast torsional waves and strong magnetic field within the Earth’s core
Numerical geodynamo models with studies of geostrophic motions in the Earth’s core that rely on geomagnetic data reconcile, finding a torsional wave recurring every six years from an ensemble inversion of core flow models.
Equatorially Dominated Magnetic Field Change at the Surface of Earth's Core
This work analyzed the evolution of nonaxisymmetric magnetic flux at the core surface over the past 400 years and found that the most robust feature is westward motion at 17 kilometers per year, in a belt concentrated around the equator beneath the Atlantic hemisphere.
Melting-induced stratification above the Earth’s inner core due to convective translation
It is shown that this layer can be generated by simultaneous crystallization and melting at the surface of the Earth’s inner core, and that a translational mode of thermal convection in the inner core can produce enough melting and crystallization on each hemisphere respectively for the dense layer to develop.
Anomalous rotation of the inner core and the toroidal magnetic field
We use numerical calculations of magnetic induction by axisymmetric motions in a spherical shell of conducting fluid to investigate the relationship between the Earth's toroidal magnetic field and