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An accelerating high-latitude jet in Earth’s core

Abstract

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 generation. High-resolution observations from the European Space Agency’s Swarm satellite mission show intense field change at high latitude, localized in a distinctive circular daisy-chain configuration centred on the north geographic pole. Here we show that this feature can be explained by a localized, non-axisymmetric, westward jet of 420 km width on the tangent cylinder, the cylinder of fluid within the core that is aligned with the rotation axis and tangent to the solid inner core. We find that the jet has increased in magnitude by a factor of three over the period 2000–2016 to about 40 km yr−1, and is now much stronger than typical large-scale flows inferred for the core. We suggest that the current accelerating phase may be part of a longer-term fluctuation of the jet causing both eastward and westward movement of magnetic features over historical periods, and may contribute to recent changes in torsional-wave activity and the rotation direction of the inner core.

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Figure 1: Polar projection view of the radial component of the main field and secular variation at the CMB from the observation-based field reconstruction CHAOS-6 at epoch 2015.
Figure 2: Northern polar view of the flow speed and direction at the CMB of the best-fitting high-latitude jet with M = 1 at epoch 2015.
Figure 3: Quantification of fit of the simple jet model.
Figure 4: A superposition of the flow direction and magnitude (arrows) and the azimuthal gradient of the radial field (in μT per °) at the CMB using CHAOS-6 at epoch 2015; together these combine to produce the SV when azimuthal advection dominates.
Figure 5: Time dependence of the jet and drift of high-latitude flux patches.

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References

  1. Finlay, C. C., Olsen, N., Kotsiaros, S., Gillet, N. & Toeffner-Clausen, L. Recent geomagnetic secular variation from Swarm and ground observatories as estimated in the CHAOS-6 geomagnetic field model. Earth Planets Space 68, 1–18 (2016).

    Article  Google Scholar 

  2. Gillet, N., Jault, D., Finlay, C. C. & Olsen, N. Stochastic modeling of the Earth’s magnetic field: inversion for covariances over the observatory era. Geochem. Geophys. Geosyst. 14, 766–786 (2013).

    Article  Google Scholar 

  3. Jackson, A., Jonkers, A. R. T. & Walker, M. R. Four centuries of geomagnetic secular variation from historical records. Phil. Trans. R. Soc. Lond. A 358, 957–990 (2000).

    Article  Google Scholar 

  4. Korte, M., Constable, C., Donadini, F. & Holme, R. Reconstructing the Holocene geomagnetic field. Earth Planet. Sci. Lett. 312, 497–505 (2011).

    Article  Google Scholar 

  5. Bloxham, J. & Gubbins, D. The secular variation of Earth’s magnetic field. Nature 317, 777–781 (1985).

    Article  Google Scholar 

  6. Korte, M. & Holme, R. On the persistence of geomagnetic flux lobes in global Holocene field models. Phys. Earth Planet. Int. 182, 179–186 (2010).

    Article  Google Scholar 

  7. Olsen, N. et al. The CHAOS-4 geomagnetic field model. Geophys. J. Int. 197, 815–827 (2014).

    Article  Google Scholar 

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

    Article  Google Scholar 

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

    Article  Google Scholar 

  10. Chulliat, A., Hulot, G. & Newitt, L. R. Magnetic flux expulsion from the core as a possible cause of the unusually large acceleration of the north magnetic pole during the 1990s. J. Geophys. Res. 115, B07101 (2010).

    Google Scholar 

  11. Lawrence, K. et al. Paleomagnetic field properties at high southern latitude. Geochem. Geophys. Geosyst. 10, Q01005 (2009).

    Article  Google Scholar 

  12. Bloxham, J., Gubbins, D. & Jackson, A. Geomagnetic secular variation. Phil. Trans. R. Soc. Lond. A 329, 415–502 (1989).

    Article  Google Scholar 

  13. Hide, R. Free hydromagnetic oscillations of the Earth’s core and the theory of geomagnetic secular variation. Phil. Trans. R. Soc. Lond. A 259, 615–647 (1966).

    Article  Google Scholar 

  14. Aurnou, J., Andreadis, S., Zhu, L. & Olson, P. Experiments on convection in Earth’s core tangent cylinder. Earth Planet. Sci. Lett. 212, 119–134 (2003).

    Article  Google Scholar 

  15. Hollerbach, R. & Proctor, M. R. E. in Solar and Planetary Dynamos (eds Proctor, M. R. E. et al.) 145–152 (Cambridge Univ. Press, 1993).

    Google Scholar 

  16. Livermore, P. & Hollerbach, R. Successive elimination of shear layers by a hierarchy of constraints in inviscid spherical-shell flows. J. Math. Phys. 53, 073104 (2012).

    Article  Google Scholar 

  17. Taylor, J. B. The magneto-hydrodynamics of a rotating fluid and the Earth’s dynamo problem. Proc. R. Soc. A 9, 274–283 (1963).

    Google Scholar 

  18. Sheyko, A., Finlay, C. C. & Jackson, A. Magnetic reversals from planetary dynamo waves. Nature 539, 551–554 (2016).

    Article  Google Scholar 

  19. Livermore, P. W., Hollerbach, R. & Jackson, A. Electromagnetically driven westward drift and inner-core superrotation in Earth’s core. Proc. Natl Acad. Sci. USA 110, 15914–15918 (2013).

    Article  Google Scholar 

  20. Labbé, F., Jault, D. & Gillet, N. On magnetostrophic inertia-less waves in quasi-geostrophic models of planetary cores. Geophys. Astrophys. Fluid Dynam. 109, 587–610 (2015).

    Article  Google Scholar 

  21. Holme, R. in Treatise on Geophysics Vol. 8 (ed. Kono, M.) 91–113 (Elsevier, 2015).

    Book  Google Scholar 

  22. Pais, A. & Jault, D. Quasi-geostrophic flows responsible for the secular variation of the Earth’s magnetic field. Geophys. J. Int. 173, 421–443 (2008).

    Article  Google Scholar 

  23. Baerenzung, J., Holschneider, M. & Lesur, V. The flow at the Earth’s core mantle boundary under weak prior constraints. J. Geophys. Res. 121, 1343–1364 (2016).

    Article  Google Scholar 

  24. Olson, P. & Aurnou, J. M. A polar vortex in the Earth’s core. Nature 402, 170–173 (1999).

    Article  Google Scholar 

  25. Aubert, J., Finlay, C. C. & Fournier, A. Bottom-up control of geomagnetic secular variation by the Earth’s inner core. Nature 502, 219–223 (2013).

    Article  Google Scholar 

  26. Jackson, A. Intense equatorial flux spots on the surface of the Earth’s core. Phys. Earth Planet. Inter. 424, 760–763 (2003).

    Google Scholar 

  27. Dumberry, M. & Finlay, C. C. Eastward and westward drift of the Earth’s magnetic field for the last three millennia. Earth Planet. Sci. Lett. 254, 146–157 (2007).

    Article  Google Scholar 

  28. Davies, C., Pozzo, M., Gubbins, D. & Alfè, D. Constraints from material properties on the dynamics and evolution of Earth’s core. Nature Geosci. 8, 678–685 (2015).

    Article  Google Scholar 

  29. Tkalc̆ić, H., Young, M., Bodin, T., Ngo, S. & Sambridge, M. The shuffling rotation of the Earth’s inner core revealed by earthquake doublets. Nature Geosci. 6, 497–502 (2013).

    Article  Google Scholar 

  30. Gillet, N., Jault, D., Canet, E. & Fournier, A. Fast torsional waves and strong magnetic field within the Earth’s core. Nature 465, 74–77 (2010).

    Article  Google Scholar 

  31. Teed, R. J., Jones, C. A. & Tobias, S. M. The transition to Earth-like torsional oscillations in magnetoconvection simulations. Earth Planet. Sci. Lett. 419, 22–31 (2015).

    Article  Google Scholar 

  32. Gillet, N., Jault, D. & Finlay, C. C. Planetary gyre, time-dependent eddies, torsional waves, and equatorial jets at the Earth’s core surface. J. Geophys. Res. 120, 3991–4013 (2015).

    Article  Google Scholar 

  33. Hunter, J. D. Matplotlib: a 2D graphics environment. Comput. Sci. Eng. 9, 90–95 (2007).

    Article  Google Scholar 

  34. Thébault, E. et al. Evaluation of candidate geomagnetic field models for IGRF-12. Earth Planets Space 67, 112 (2015).

    Article  Google Scholar 

  35. Sabaka, T. J., Olsen, N., Tyler, R. H. & Kuvshinov, A. CM5, a pre-Swarm comprehensive geomagnetic field model derived from over 12 yr of CHAMP, Ørsted, SAC-C and observatory data. Geophys. J. Int. 200, 1596–1626 (2015).

    Article  Google Scholar 

  36. Lesur, V., Wardinski, I., Rother, M. & Mandea, M. GRIMM: the GFZ reference internal magnetic model based on vector satellite and observatory data. Geophys. J. Int. 173, 382–394 (2008).

    Article  Google Scholar 

  37. Lesur, V., Wardinski, I., Hamoudi, M. & Rother, M. The second generation of the GFZ reference internal magnetic model: GRIMM-2. Earth Planets Space 62, 765–773 (2010).

    Article  Google Scholar 

  38. Olsen, N. et al. The Swarm initial field model for the 2014 geomagnetic field. Geophys. Res. Lett. 42, 1092–1098 (2015).

    Article  Google Scholar 

  39. Olsen, N. et al. The Swarm satellite constellation application and research facility (SCARF) and Swarm data products. Earth Planets Space 65, 1189–1200 (2013).

    Article  Google Scholar 

  40. Maus, S., Manoj, C., Rauberg, J., Michaelis, I. & Lühr, H. NOAA/NGDC candidate models for the 11th generation International Geomagnetic Reference Field and the concurrent release of the 6th generation Pomme magnetic model. Earth Planets Space 62, 729–735 (2010).

    Article  Google Scholar 

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Acknowledgements

Swarm data used in the construction of the magnetic field models were provided by the European Space Agency. The support of the CHAMP mission by the German Aerospace Center (DLR) and the Federal Ministry of Education and Research is gratefully acknowledged. The staff of the geomagnetic observatories and INTERMAGNET are thanked for supplying high-quality observatory data. The deep-Earth research group within the School of Earth and Environment, University of Leeds, is thanked for comments and discussion on an early version of this manuscript. The figures were produced using the Python package Matplotlib33. The authors would like to thank R. Holme and I. Wardinski for constructive comments that helped improve the manuscript. P.W.L. was partially supported by the NERC grant NE/G014043/1.

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All authors contributed to the design and rationale of this work. C.C.F. provided and commented on the observational field models; P.W.L. and R.H. devised the numerical scheme. P.W.L. performed the calculations and wrote the paper, on which all authors commented.

Corresponding author

Correspondence to Philip W. Livermore.

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Livermore, P., Hollerbach, R. & Finlay, C. An accelerating high-latitude jet in Earth’s core. Nature Geosci 10, 62–68 (2017). https://doi.org/10.1038/ngeo2859

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