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Time evolution of the fluid flow at the top of the core. Geomagnetic jerks

Earth, Planets and Space volume 52, pages 163–173 (2000)Cite this article

Abstract

The knowledge of the geomagnetic field and its secular variation allows us to compute the fluid flow at the core surface. The poloidal and toroidal components of the fluid flow at the core-mantle boundary (CMB) have been calculated every year from the Bloxham and Jackson model (1992) and plotted at 50 year intervals over the last three centuries. The flow patterns conserve some broad features over this whole time-span. The time constant of the degree 1 component of the motion is larger than the time constant of the rest of the flow. The average motion over 300 years appears to be in large part symmetrical with respect to the equator. This average flow can be represented by the sum of a few geostrophic vectors. The acceleration fields corresponding to the well documented jerks of 1969, 1979, 1992 have also been computed. The geometry of these acceleration fields is the same, within a change of sign, for the three events. Moreover, this geometry has close connections with the geometry of the flow itself. The spatial and temporal variations of the flow field can be simply described, in a first approximation; it is possible to give an analytical schematic representation of the flow field during the last three decades. Some characteristics of the decadal length-of-day variations follow if the coupling torque between core and mantle is topographic.

References

  • Alexandrescu, M., D. Gibert, G. Hulot, J. -L. Le Mouël, and G. Saracco, Detection of geomagnetic jerks using wavelet analysis, J. Geophys. Res., 100(B7), 12557–12572, 1995.

    Article  Google Scholar 

  • Alexandrescu, M., D. Gibert, G. Hulot, J. -L. Le Mouël, and G. Saracco, Worldwide wavelet analysis of geomagnetic jerks, J. Geophys. Res., 101(B10), 21975–21994, 1996.

    Article  Google Scholar 

  • Backus, G. E., Poloidal and toroidal fields in geomagnetic field modeling, Rev. Geophys., 24, 75–109, 1986.

    Article  Google Scholar 

  • Backus, G. E. and J. -L. Le Mouël, The region of the core-mantle boundary where geostrophic velocity fields can be determined from frozen-flux magnetic data, Geophys. J. R. Astron. Soc., 85, 617–628, 1986.

    Article  Google Scholar 

  • Barraclough, D. R., Spherical harmonic analyses of the geomagnetic field for eight epochs between 1600 and 1910, Geophys. J. R. Astron. Soc., 36, 497–513, 1974.

    Article  Google Scholar 

  • Benkova, N. P., G. I. Kolomiytseva, and T. N. Cherevko, Analytical model of the geomagnetic field and its secular variation over a period of 400 years (1550–1950), Geomagn. Aeron., 14, 751–755, 1974.

    Google Scholar 

  • Bloxham, J. and D. Gubbins, The secular variation of Earth’s magnetic field, Nature, 317, 777–781, 1985.

    Article  Google Scholar 

  • Bloxham, J. and A. Jackson, Time-dependent mapping of the magnetic field at the core-mantle boundary, J. Geophys. Res., 97, 19537–19564, 1992.

    Article  Google Scholar 

  • Braginsky, S. I., Spherical analyses of the main geomagnetic field in 1550–1800, Geomag. Aeron., 12, 524–529, 1972.

    Google Scholar 

  • Carlut, J. and V. Courtillot, Geomagnetic paleosecular variation in the last 5 million years: How many multipoles are actually resolvable? (abstract), EOS Suppl., 76(46), 166, 1995.

    Google Scholar 

  • Carlut, J. and V. Courtillot, How complex is the time-averaged geomagnetic field over the past 5 Myr?, Geophys. J. Int, 134, 527–544, 1998.

    Article  Google Scholar 

  • Chulliat, A. and G. Hulot, Local computation of the geostrophic pressure at the top of the core, Phys. Earth Planet. Inter., 117, 309–328, 2000.

    Article  Google Scholar 

  • Courtillot, V. and J. -L. Le Mouël, Geomagnetic secular variation impulses, Nature, 311, 709–716, 1984.

    Article  Google Scholar 

  • Courtillot, V, J. Ducruix, and J. -L. Le Mouël, Sur une accélération récente de la variation séculaire du champ magnétique terrestre, C. R. Acad. Sci. Paris, 287, Série D., 1095–1098, 1978.

    Google Scholar 

  • De Michelis, P., L. Cafarella, and A. Meloni, Worldwide character of the 1991 jerk, Geophys. Res. Lett., 25, 377–380, 1998.

    Article  Google Scholar 

  • Forte, A. M., J. X. Mitrovica, and R. L. Woodward, Seismic-geodynamic determination of the origin of excess ellipicity of the core-mantle boundary, Geophys. Res. Lett., 22(9), 1013–1016, 1995.

    Article  Google Scholar 

  • Fritsche, H., Atlas des Erdmagnetismus, pp. 1–26, Riga, 1903.

  • Gavoret, J., D. Gibert, M. Menvielle, and J. -L. Le Mouël, Long-term variations of the external and internal components of the Earth’s magnetic field, J. Geophys. Res., 91(B5), 4787–4796, 1986.

    Article  Google Scholar 

  • Gire, C. and J. -L. Le Mouël, Tangentially geostrophic flow at the core-mantle boundary compatible with the observed geomagnetic secular variation: the large-scale component of the flow, Phys. Earth Planet. Inter., 59, 259–287, 1990.

    Article  Google Scholar 

  • Gire, C., J. -L. Le Mouël, and J. Ducruix, Evolution of the geomagnetic secular variation field from the beginning of the century, Nature, 307, 349–352, 1984.

    Article  Google Scholar 

  • Gire, C., J. -L. Le Mouël, and T. Madden, Motions at the core surface derived from secular variation data, Geophys. J. R. Astron. Soc., 84, 1–29, 1986.

    Article  Google Scholar 

  • Golovkov, V. P., T. I. Zvereva, and A. O. Simonyan, Common features and differences between “jerks” of 1947,1958 and 1969, Geophys. Astrophys. Fluid Dyn., 49, 81–96, 1989.

    Article  Google Scholar 

  • Gubbins, D. and J. Bloxham, Morphology of the geomagnetic field and implications for the geodynamo, Nature, 325, 509–511, 1987.

    Article  Google Scholar 

  • Gubbins, D. and L. Tomlinson, Secular variation from monthly means from Apia and Amberley magnetic observatories, Geophys. J. R. Astron. Soc., 86, 603–616, 1986.

    Article  Google Scholar 

  • Gubbins, D. and P. Kelly, Persistent patterns in the geomagnetic field over the past 2.5 Myr, Nature, 365, 829–832, 1993.

    Article  Google Scholar 

  • Hide, R., Fluctuations in the Earth’s rotation and the topography of the core-mantle interface, Phil. Trans. R. Soc. Lond., A328, 351–363, 1989.

    Article  Google Scholar 

  • Hide, R., R. W. Clayton, B. H. Hager, M. A. Speith, and C. V. Voorhies, Topographic core-mantle coupling and fluctuations in the Earth’s rotation, in Relating Geophysical Structures and Processes: The Jeffreys Volume, edited by K. Aki and R. Dmowska, Geophys. Monog., Amer. Geophys. Un., 76, 107–120, 1993.

  • Hulot, G. and J. -L. Le Mouël, A statistical approach to the Earth’s main magnetic field, Phys. Earth Planet. Inter., 82, 167–183, 1994.

    Article  Google Scholar 

  • Hulot, G., J. -L. Le Mouël, and D. Jault, The flow at the core-mantle boundary: symmetry properties, J. Geomag. Geoelectr., 42, 857–874, 1990.

    Article  Google Scholar 

  • Hulot, G., J. -L. Le Mouël, and J. Wahr, Taking into account truncation problems and geomagnetic model accuracy in assessing computed flows at the core-mantle boundary, Geophys. J. Int., 108, 224–246, 1992.

    Article  Google Scholar 

  • Jault, D. and J. -L. Le Mouël, The topographic torque associated with a tangentially geostrophic motion at the core surface and inferences on the flow inside the core, Geophys. Astrophys. Fluid Dyn., 48, 273–296, 1989.

    Article  Google Scholar 

  • Jault, D. and J. -L. Le Mouël, Core mantle boundary shape: constraints inferred from the pressure torque acting between the core and the mantle, Geophys. J. Int., 101, 233–241, 1990.

    Article  Google Scholar 

  • Jault, D. and J. -L. Le Mouël, Exchange of angular momentum between the core and the mantle, J. Geomag. Geoelectr., 43, 111–129, 1991.

    Article  Google Scholar 

  • Jault, D. and J. -L. Le Mouël, Comment on ‘On the dynamics of topographical core-mantle coupling’ by Weijia Kuang and Jeremy Bloxham, Phys. Earth Planet. Inter., 114, 211–215, 1999.

    Article  Google Scholar 

  • Kelly, P. and D. Gubbins, The geomagnetic field over the past 5 million years, Geophys. J. Int., 128, 315–330, 1997.

    Article  Google Scholar 

  • Kerridge, D. J. and D. R. Barraclough, Evidence for geomagnetic jerks from 1931 to 1971, Phys. Earth Planet. Inter., 39, 228–236, 1985.

    Article  Google Scholar 

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

    Article  Google Scholar 

  • Le Mouël, J. -L., C. Gire, and T. Madden, Motions at the core surface in the geostrophic approximation, Phys. Earth Planet. Inter., 39, 270–287, 1985.

    Article  Google Scholar 

  • Le Huy, M., M. Alexandrescu, G. Hulot, and J. -L. Le Mouël, On the characteristics of successive geomagnetic jerks, Earth Planets Space, 50, 723–732, 1998.

    Article  Google Scholar 

  • Macmillan, S., A geomagnetic jerk for the early 1990’s, Earth Planet. Sci. Lett., 137, 189–192, 1996.

    Article  Google Scholar 

  • Malin, S. R. C., Geomagnetic secular variation and its changes, 1942.5 to 1962.5, Geophys. J. R. Astron. Soc., 17, 415–441, 1969.

    Article  Google Scholar 

  • Malin, S. R. C. and A. D. Clark, Geomagnetic secular variation, 1962.5 to 1967.5, Geophys. J. R. Astron. Soc., 36, 11–20, 1974.

    Article  Google Scholar 

  • Malin, S.R. C. and B.M. Hodder, Was the 1970 geomagneticjerk of internal or external origin?, Nature, 296, 726–728, 1982.

    Article  Google Scholar 

  • Malin, S. R. C., B. M. Hodder, and D. R. Barraclough, Geomagnetic secular variation: a jerk in 1970, in 75th Anniversary Volume of Ebro Observatory, edited by J. O. Cardús, pp. 239–256, Ebro Obs., Tarragona, Spain, 1983.

    Google Scholar 

  • McLeod, M. G., On the Geomagneticjerk of 1969, J. Geophys. Res., 90, 4597–4610, 1985.

    Article  Google Scholar 

  • Morelli, A. and M. Dziewonski, Topography of the core-mantle boundary and lateral homogeneity of the liquid core, Nature, 325, 678–683, 1987.

    Article  Google Scholar 

  • Pais, A., G. Hulot, M. Mandea Alexandrescu, Does the geomagnetic secular variation anticipate or correlate with decade length of day variations? (Abstract), IUGG Birmingham, 1999.

  • Roberts, P. H. and S. Scott, On the analysis of the secular variation. 1. A hydromagnetic constraint: theory, J. Geomag. Geoelectr., 17, 137–151, 1965.

    Article  Google Scholar 

  • Stewart, D. N. and K. Whaler, Geomagnetic disturbance fields: An analysis of observatory monthly means, Geophys. J. Int., 108, 215–223, 1992.

    Article  Google Scholar 

  • Whaler, K. A., A new method for analysing geomagnetic impulses, Phys. Earth Planet. Inter., 48, 221–240, 1987.

    Article  Google Scholar 

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Authors and Affiliations

  1. Institut de Physique du Globe de Paris, B.P. 89, 4 Place Jussieu, 75252, Paris cedex 5, France

    Minh Le Huy, Mioara Mandea, Jean-Louis Le Mouël & Alexandra Pais

  2. Hanoi Institute of Geophysics, Nghia do - Tu Liem - Hanoi, Vietnam

    Minh Le Huy

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  1. Minh Le Huy
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  2. Mioara Mandea
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  3. Jean-Louis Le Mouël
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  4. Alexandra Pais
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Correspondence to Minh Le Huy.

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Le Huy, M., Mandea, M., Le Mouël, JL. et al. Time evolution of the fluid flow at the top of the core. Geomagnetic jerks. Earth Planet Sp 52, 163–173 (2000). https://doi.org/10.1186/BF03351625

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Keywords

  • Secular Variation
  • Core Surface
  • Antisymmetric Part
  • Core Mantle Boundary
  • Geomagnetic Jerk