Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Rapidly changing flows in the Earth’s core

Nature Geoscience volume 1, pages 390–394 (2008)Cite this article

Abstract

A large part of the Earth’s magnetic field is generated by fluid motion in the molten outer core1. As a result of continuous satellite measurements since 1999, the core magnetic field and its recent variations can now be described with a high resolution in space and time2. These data have recently been used to investigate small-scale core flow3,4, but no advantage has yet been taken of the improved temporal resolution, partly because the filtering effect of the electrically conducting mantle was assumed to mask short-period magnetic variations5. Here we show that changes in the magnetic field occurring over only a few months, indicative of fluid flow at the top of the core, can in fact be resolved. Using nine years of magnetic field data obtained by satellites as well as Earth-based observatories, we determine the temporal changes in the core magnetic field and flow in the core. We find that the core flow is spatially localized and involves rapid variations over a few months, with surprisingly large local accelerations. Our results suggest that short-term fluctuations of the core magnetic field are robust features of rapid core dynamics and should be considered in the development of future numerical models of the geodynamo.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Get just this article for as long as you need it

$39.95

Learn more

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Observed and modelled secular variation.
Figure 2: Map of annual difference of the second time derivative of the vertical component for epoch 2003.5.
Figure 3: Map of annual difference of the second time derivative of the vertical component for epoch 2004.7.
Figure 4: Observed and modelled LOD variations.

References

  1. Merrill, R., McFadden, P. & McElhinny, M. The Magnetic Field of the Earth: Paleomagnetism, the Core, and the Deep Mantle (Academic, San Diego, 1998).

    Google Scholar 

  2. Olsen, N. et al. CHAOS—a model of Earth’s magnetic field derived from CHAMP, Ørsted, and SAC-C magnetic satellite data. Geophys. J. Int. 166, 67–75 (2006).

    Article  Google Scholar 

  3. Hulot, G., Eymin, C., Langlais, B., Mandea, M. & Olsen, N. Small-scale structure of the geodynamo inferred from Ørsted and Magsat satellite data. Nature 416, 620–623 (2002).

    Article  Google Scholar 

  4. Holme, R. & Olsen, N. Core–surface flow modelling from high resolution secular variation. Geophys. J. Int. 518–528 (2006).

  5. Backus, G. E. Application of mantle filter theory to the magnetic jerk of 1969. Geophys. J. R. Astron. Soc. 74, 713–746 (1983).

    Google Scholar 

  6. Olsen, N. & Mandea, M. Investigation of a secular variation impulse using satellite data: The 2003 geomagnetic jerk. Earth Planet. Sci. Lett. 255, 94–105 (2007).

    Article  Google Scholar 

  7. Holme, R. in Treatise on Geophysics Vol. 8 (ed. Olson, P.) (Elsevier, Amsterdam, 2007).

    Google Scholar 

  8. Shankland, T. J., Peyronneau, J. & Poirier, J.-P. Electrical conductivity of the earth’s lower mantle. Nature 366, 453–455 (1993).

    Article  Google Scholar 

  9. Xu, Y., McCammon, C. & Poe, B. The effect of alumina on the electrical conductivity of silicate perovskite. Science 282, 922 (1998).

    Article  Google Scholar 

  10. Medin, A., Parker, R. & Constable, S. Making sound inferences from geomagnetic sounding. Phys. Earth Planet. Int. 160, 51–59 (2007).

    Article  Google Scholar 

  11. Bullard, E. C. & Gellmann, H. Homogeneous dynamos and terrestrial magnetism. Phil. Trans. R. Soc. Lond. A 247, 213–255 (1954).

    Article  Google Scholar 

  12. Roberts, P. & Scott, S. On the analysis of the secular variation, 1, A hydromagnetic constraint: Theory. J. Geomagn. Geoelectr. 17, 137–151 (1965).

    Article  Google Scholar 

  13. Gubbins, D. Finding core motions from magnetic observations. Phil. Trans. R. Soc. Lond. A 306, 247–254 (1982).

    Article  Google Scholar 

  14. Bloxham, J. & Jackson, A. Time-dependent mapping of the magnetic field at the core–mantle boundary. J. Geophys. Res. 97, 19537–19563 (1992).

    Article  Google Scholar 

  15. Waddington, R., Gubbins, D. & Barber, N. Geomagnetic field analysis-V. Determining steady core–surface flows directly from geomagnetic observations. Geophys. J. Int. 122, 326–350 (1995).

    Article  Google Scholar 

  16. Bloxham, J., Zatman, S. & Dumberry, M. The origin of geomagnetic jerks. Nature 420, 65–68 (2002).

    Article  Google Scholar 

  17. Whaler, K. A. Does the whole of the Earth’s core convect? Nature 287, 528–530 (1980).

    Article  Google Scholar 

  18. Hills, R. Convection in the Earth’s Mantle Due to Viscous Shear at the Core–Mantle Interface and Due to Large Scale Buoyancy. PhD Thesis, New Mexico State Univ. (1979).

  19. Le Mouël, J.-L. Outer-core geostrophic flow and secular variation of Earth’s geomagnetic field. Nature 311, 734–735 (1984).

    Article  Google Scholar 

  20. Amit, H. & Olson, P. Helical core flow from geomagnetic secular variation. Phys. Earth Planet. Int. 147, 1–25 (2004).

    Article  Google Scholar 

  21. Pais, M., Oliveira, O. & Nogueira, F. Nonuniqueness of inverted core–mantle boundary flows and deviations from tangential geostrophy. J. Geophys. Res. 109, 8105–8200 (2004).

    Article  Google Scholar 

  22. Jault, D., Gire, C. & Le Mouël, J.-L. Westward drift, core motions and exchanges of angular momentum between core and mantle. Nature 333, 353–356 (1988).

    Article  Google Scholar 

  23. Jackson, A., Bloxham, J. & Gubbins, D. Dynamics of the Earth’s Deep Interior and Earth Rotation Vol. 72, 97–107 (AGU, Washington, 1993).

    Google Scholar 

  24. Holme, R. & de Viron, O. Geomagnetic jerks and a high-resolution length-of-day profile for core studies. Geophys. J. Int. 160, 435–439 (2005).

    Article  Google Scholar 

  25. Gubbins, D. in Encyclopedia of Geomagnetism and Paleomagnetism (eds Gubbins, D. & Herrero-Bervera, E.) (Springer, Heidelberg, 2007).

    Book  Google Scholar 

  26. Finlay, C. & Jackson, A. Equatorially dominated magnetic field change at the surface of Earth’s core. Science 300, 2084–2086 (2003).

    Article  Google Scholar 

  27. Jault, D. Axial invariance of rapidly varying diffusionless motions in the Earth’s core interior. Phys. Earth Planet. Int. 166, 67–76 (2008).

    Article  Google Scholar 

Download references

Acknowledgements

We thank Chris Finlay and Dominique Jault for comments and discussion.

Author information

Authors and Affiliations

  1. Danish National Space Center/DTU and Niels Bohr Institute at Copenhagen University, Juliane Maries Vej 30, 2100 Copenhagen, Denmark

    Nils Olsen

  2. GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany

    Mioara Mandea

Authors
  1. Nils Olsen
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Mioara Mandea
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Nils Olsen.

Supplementary information

Supplementary Information

Supplementary figures S1-S2 and tables S1-S2 (PDF 141 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Olsen, N., Mandea, M. Rapidly changing flows in the Earth’s core. Nature Geosci 1, 390–394 (2008). https://doi.org/10.1038/ngeo203

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/ngeo203

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing