# Tidal dissipation and the strength of the Earth’s internal magnetic field

@article{Buffett2010TidalDA, title={Tidal dissipation and the strength of the Earth’s internal magnetic field}, author={B. Buffett}, journal={Nature}, year={2010}, volume={468}, pages={952-954} }

Magnetic fields at the Earth’s surface represent only a fraction of the field inside the core. The strength and structure of the internal field are poorly known, yet the details are important for our understanding of the geodynamo. Here I obtain an indirect estimate for the field strength from measurements of tidal dissipation. Tidally driven flow in the Earth’s liquid core develops internal shear layers, which distort the internal magnetic field and generate electric currents. Ohmic losses… Expand

#### 62 Citations

Tidal dissipation in rotating fluid bodies: the presence of a magnetic field

- Physics
- 2017

We investigate effects of the presence of a magnetic field on tidal dissipation in rotating fluid bodies. We consider a simplified model consisting of a rigid core and a fluid envelope, permeated by… Expand

Analytical Estimation of the Scale of Earth-Like Planetary Magnetic Fields

- Physics
- 2014

In this paper we analytically estimate the magnetic field scale of planets with physical core conditions similar to that of Earth from a statistical physics point of view. We evaluate the magnetic… Expand

On Ohmic heating in the Earth’s core II: Poloidal magnetic fields obeying Taylor’s constraint

- Physics
- 2011

Abstract The extremely small Ekman and magnetic Rossby numbers in the Earth’s core make the magnetostrophic limit an attractive approximation to the core’s dynamics. This limit leads to the need for… Expand

Geodynamo models: Tools for understanding properties of Earth’s magnetic field

- Physics
- 2011

Abstract Self-consistent models of the dynamo process in the Earth’s core have reached a state where they can be used to understand specific morphological and temporal properties of the geomagnetic… Expand

The role of the magnetic field morphology on the electromagnetic coupling for nutations

- Physics
- 2013

SUMMARY Observations of the Earth’s nutations provide constraints on the mechanical coupling at the core–mantle and inner core boundaries. An important physical mechanism that could be responsible… Expand

Earth's Inner Core dynamics induced by the Lorentz force

- Physics, Geology
- 2015

Seismic studies indicate that the Earth's inner core has a complex structure and exhibits a strong elastic anisotropy with a cylindrical symmetry. Among the various models which have been proposed to… Expand

Analytical estimation of the Earth's magnetic field scale

- Physics
- 2012

In this paper we analytically estimate the magnetic field scale of planets with physical core conditions similar to that of Earth from a statistical point of view. We evaluate the magnetic field on… Expand

Ohmic dissipation in the Earth's outer core resulting from the free inner core nutation

- Geology, Physics
- 2019

Abstract The diurnal tidal forces can excite a normal mode of the Earth's core, the free inner core nutation (FICN), which is characterized by a tilt of the rotation axis of the inner core with… Expand

The Magnetic Effect on Dynamical Tide in Rapidly Rotating Astronomical Objects

- Physics
- 2018

By numerically solving the equations of rotating magnetohydrodynamics, we study the magnetic effect on dynamical tide. We find that a magnetic field has a significant impact not only on the flow… Expand

Waves in the core and mechanical core-mantle interactions

- Physics
- 2015

This chapter focuses on time-dependent fluid motions in the core interior, which can be constrained by observations of Earth's magnetic field, on timescales that are short compared to the magnetic… Expand

#### References

SHOWING 1-10 OF 34 REFERENCES

Fast torsional waves and strong magnetic field within the Earth’s core

- Physics, Medicine
- Nature
- 2010

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. Expand

Torsional oscillations and the magnetic field within the Earth's core

- Physics
- Nature
- 1997

An estimate of the magnitude and geometry of the magnetic field within the Earth's core would be valuable for understanding the dynamics of the liquid outer core and for constraining numerical models… Expand

Inversion of torsional oscillations for the structure and dynamics of Earth's core

- Physics
- 2009

SUMMARY
Oscillations in Earth's liquid core with periods of several decades are inferred from variations in the magnetic field. The observed periods are consistent with a type of hydromagnetic wave… Expand

Typical Velocities and Magnetic Field Strengths in Planetary Interiors

- Physics
- 2002

Recent studies of convection-driven dynamos in the outer core of the Earth have improved our understanding of the dynamical regime in fluid planetary cores. We consider the possible dynamical regimes… Expand

Power requirement of the geodynamo from ohmic losses in numerical and laboratory dynamos

- Physics, Medicine
- Nature
- 2004

Modelling the ohmic dissipation of the Karlsruhe dynamo experiment supports a simple dependence on the magnetic Reynolds number alone, indicating that flow turbulence in the experiment and in the Earth's core has little influence on its characteristic dissipation time. Expand

The viscosity of liquid iron at the physical conditions of the Earth's core

- Physics
- Nature
- 1998

It is thought that the Earth's outer core consists mainly of liquid iron and that the convection of this metallic liquid gives rise to the Earth's magnetic field. A full understanding of this… Expand

On Ohmic heating in the Earth's core I: Nutation constraints

- Physics
- 2009

SUMMARY We present calculations to place formal lower bounds on the energy dissipated by the magnetic field in the core. These bounds are discovered by solving for 3-D magnetic fields in the Earth’s… Expand

Modeling of nutation and precession: Effects of electromagnetic coupling

- Physics, Geology
- 2002

[1] The presence of an internal magnetic field influences of the Earth's nutation through the effects of electromagnetic torques at the boundaries of the fluid core. We calculate the effect of… Expand

Numerical Modeling of Magnetohydrodynamic Convection in a Rapidly Rotating Spherical Shell

- Physics
- 1999

In this paper we describe a numerical model for investigating magnetohydrodynamic (MHD) convective flow of a Boussinesq fluid in a rapidly rotating spherical shell, driven by the buoyancy forces… Expand

Scaling properties of convection-driven dynamos in rotating spherical shells and application to planetary magnetic fields

- Physics
- 2006

SUMMARY We study numerically an extensive set of dynamo models in rotating spherical shells, varying all relevant control parameters by at least two orders of magnitude. Convection is driven by a… Expand