On flow magnitude and field-flow alignment at Earth's core surface

Geophysical Journal International

Volumn 186, Issue 1, 2011, Pages 175-192

  Finlay, Christopher C ^a   Amit, Hagay ^b  

^a ETH ZURICH   (Switzerland)

^b UNIVERSITÉ DE NANTES   (France)

Author keywords

Dynamo: theories and simulations; Planetary interiors; Satellite magnetics

Indexed keywords

EXTRAPOLATION; INTERACTIVE DEVICES; NUMERICAL METHODS;

DYNAMO: THEORIES AND SIMULATIONS; GEOMAGNETIC FIELD MODEL; GEOMAGNETIC MAIN FIELD; HISTORICAL GEOMAGNETIC FIELDS; MAGNETIC INDUCTION EQUATIONS; PLANETARY INTERIORS; SATELLITE MAGNETICS; SPECTRAL EXTRAPOLATION;

GEOMAGNETISM;

CORE (PLANETARY); GEODYNAMO; GEOMAGNETIC FIELD; NUMERICAL MODEL; RAYLEIGH NUMBER; SATELLITE DATA; SECULAR VARIATION; SPECTRAL ANALYSIS; SPHERICAL HARMONICS; TEMPORAL VARIATION;

RAETA;

EID: 79959269328     PISSN: 0956540X     EISSN: 1365246X     Source Type: Journal    
DOI: 10.1111/j.1365-246X.2011.05032.x     Document Type: Article

References (97)

1. Amit, H. & Christensen, U.R., 2008. Accounting for magnetic diffusion in core flow inversions from geomagnetic secular variation, Geophys. J. Int., 175, 913-924.
2. Amit, H. & Olson, P., 2004. Helical core flow from geomagnetic secular variation, Phys. Earth planet. Inter., 147, 1-25.
3. Amit, H. & Olson, P., 2006. Time-average and time-dependent parts of core flow, Phys. Earth planet. Inter., 155, 120-139.
4. Amit, H., Olson, P. & Christensen, U.R., 2007. Tests of core flow imaging methods with numerical dynamos, Geophys. J. Int., 168, 27-39.
5. Amit, H., Aubert, J. & Hulot, G., 2010. Stationary, oscillating or drifting mantle-driven flux patches, J. geophys. Res., 115, doi:.
6. Archontis, V., Dorch, S.B.F. & Nordlund, A., 2007. Nonlinear MHD dynamo operating at equipartition, Astron. Astrophys., 472, 715-726.
7. Backus, G., 1968. Kinematics of geomagnetic secular variation in a perfectly conducting core, Phil. Trans. R. Soc. Lond. A., 263, 239-266.
8. Backus, G. & LeMouël, J.L., 1986. The region on the core mantle boundary where a geostrophic velocity field can be determined from frozen flux magnetic data, Geophys. J. R. astr. Soc., 85, 617-628.
9. Backus, G., Parker, R.L. & Constable, C.G., 1996. Foundations of Geomagnetism, pp. 247-260, Cambridge Univ. Press, Cambridge .
10. Beggan, C. & Whaler, K., 2008. Core flow modelling assumptions, Phys. Earth planet. Inter., 167, 217-222.
11. Bloxham, J., 1989. Simple models of fluid flow at the core surface derived from geomagentic field models, Geophys. J. Int., 99, 173-182.
12. Bloxham, J., 1992. The steady part of the secular variation of the Earth's magnetic field, J. geophys. Res., 97, 19565-19579.
13. Bloxham, J. & Gubbins, D., 1986. Geomagnetic field analysis, IV. Testing the frozen-flux hypothesis, Geophys. J. Int., 84, 139-152.
14. Bloxham, J. & Jackson, A., 1989. Simultaneous stochastic inversion for geomagnetic main field and secular variation, II: 1820-1980, J. geophys. Res., 94, 15753-15769.
15. Bloxham, J. & Jackson, A., 1991. Fluid flow near the surface of the Earth's outer core, Rev. Geophys., 29, 97-120.
16. Booker, J.R., 1969. Geomagnetic data and core motions, Proc. R. Soc. Lond. A., 309, 27-40.
17. Brandenberg, A., 2009. Large scale dynamos at low magnetic Prandtl numbers, Astrophys. J., 697, 1206-1213.
18. Brito, D., Nataf, H., Cardin, P., Aubert, J. & Masson, J.P., 2001. Ultrasonic doppler velocimetry in liquid gallium, Exp. Fluids, 31, 653-663.
19. Buffett, B.A. & Christensen, U.R., 2007. Magnetic and viscous coupling at the core-mantle boundary: inferences from observations of the Earth's nutations, Geophys. J. Int., 171, 145-157.
20. Bullard, E.C. & Gellman, H., 1950. Homogeneous dynamos and terrestrial magnetism, Phil. Trans. R. Soc. Lond. A., 247, 213-278.
21. Bullard, E.C., Freedman, C., Gellman, H. & Nixon, J., 1950. The westward drift of the Earth's magnetic field, Phil. Trans. R. Soc. Lond. A., 243, 67-92.
22. Cameron, R. & Galloway, D., 2006. Saturation properties of the Archontis dynamo, Mon. Not. R. astr. Soc., 365, 735-746.
23. Cardin, P. & Brito, D., 2007. Survey of experimental results, in Mathematical Aspects of Natural Dynamos, pp. 361-407, eds Dormy, E. & Soward, A.M., CRC Press, Boca Raton, FL.
24. Cattaneo, F. & Tobias, S.M., 2009. Dynamo properties of the turbulent velocity field of a saturated dynamo, J. Fluid. Mech., 621, 205-214.
25. Christensen, U.R., 2010. Dynamo scaling laws and applications to the planets, Space Sci. Rev., 152, 565-590.
26. Christensen, U.R. & Aubert, J., 2006. Scaling properties of convection-driven dynamos in rotating spherical shells and applications to planetary magnetic fields, Geophys. J. Int., 166, 97-114.
27. Christensen, U.R. & Tilgner, A., 2004. Power requirement of the geodynamo from ohmic losses in numerical and laboratory dynamos, Nature, 439, 169-171.
28. Christensen, U.R. et al., 2001. A numerical dynamo benchmark, Phys. Earth. planet. Int., 128, 25-34.
29. Chulliat, A. & Olsen, N., 2010. Observation of magnetic diffusion in the Earth's outer core from Magsat, Ørsted, and CHAMP data, J. geophys. Res., 115, B05105, doi:.
30. Deleplace, B. & Cardin, P., 2006. Viscomagnetic torque at the core mantle boundary, Geophys. J. Int., 167, 557-566.
31. Elsasser, W.M., 1939. On the origin of the Earth's magnetic field, Phys. Rev, 55, 489-498.
32. Elsasser, W.M., 1946. Induction effects in terrestrial magnetism. Part II. The secular variation, Phys. Rev, 70, 202-212.
33. Elsasser, W.M., 1950a. The Earth's interior and geomagnetism, Rev. Mod. Phys., 22, 1-40.
34. Elsasser, W.M., 1950b. The hydromagnetic equations, Phys. Rev, 79, 183-183.
35. Eymin, C. & Hulot, G., 2005. On surface core flows inferred from satellite magnetic data, Phys. Earth planet. Inter., 152, 200-220.
36. Finlay, C.C., Dumberry, M., Chulliat, A. & Pais, M., 2010. Short timescale core dynamics: theory and observationns, Space Sci. Rev., 155, 177-218.
37. Gillet, N., Pais, M.A. & Jault, D., 2009. Ensemble inversion of time-dependent core flow models., Geochem. Geophys. Geosyst., 10, Q06004, doi:.
38. Gillet, N., Lesur, V. & Olsen, N., 2010. Ensemble inversion of time-dependent core flow models., Space Sci. Rev., 155, 129-145.
39. Gire, C. & LeMouël, J.L., 1990. 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.
40. Gubbins, D., Barber, C.N., Gibbons, S. & Love, J.J., 2000. Kinematic dynamo action in a sphere: I effects of differential rotation and meridional circulation on solutions with axial dipole symmetry, Proc. R. Soc. Lond., A456, 1333-1353.
41. Holme, R., 2007. Large-scale flow in the core, in Treatise on Geophysics, Vol. 8, pp. 107-130, ed. Olson, P., Elsevier Science, Amsterdam.
42. Holme, R. & Olsen, N., 2006. Core surface flow modelling from high-resolution secular variation, Geophys. J. Int., 166, 518-528.
43. Hulot, G. & LeMouël, J.L., 1994. A statistical approach to the Earth's main magnetic field, Phys. Earth planet. Inter., 82, 167-183.
44. Hulot, G., LeMouël, J.L. & Wahr, J., 1992. Taking into account truncation problems and geomagnetic model accuracy in assessing computed flows at the core-mantle boundary, Geophys. J. Int., 108, 224-246.
45. Jackson, A., 1997. Time-dependency of tangentially geostrophic core surface motions, Phys. Earth planet. Inter., 103, 293-311.
46. Jackson, A. & Finlay, C.C., 2007. Geomagnetic secular variation and its applications to the core, in Treatise on Geophysics, Vol. 5, pp. 147-193, ed. Olson, P., Elsevier Science, Amsterdam.
47. Jackson, A. & Livermore, P.W., 2008. On Ohmic heating in the Earth's core I: nutation constraints, Geophys. J. Int., 177, 367-382.
48. Jackson, A., Bloxham, J. & Gubbins, D., 1993. Time-dependent flow at the core surface and conservation of angular momentum in the coupled core-mantle system, in Dynamics of Earth's Deep Interior and Earth Rotation, eds LeMouël, J.-L., Smylie, D. & Herring, T., AGU/IUGG.
49. Jackson, A., Jonkers, A.R.T. & Walker, M.R., 2000. Four centuries of geomagnetic secular variation from historical records, Phil. Trans. R. Soc. Lond., A358, 957-990.
50. Kahle, A., Ball, R.H. & Vestine, E.H., 1967a. Comparison of estimated surface fluid motions of the core for various epochs, J. geophys. Res., 72, 1095-1108.
51. Kahle, A., Vestine, E.H. & Ball, R., 1967b. Estimated surface motions of the Earth's core, J. geophys. Res., 72, 4917-4925.
52. Kutzner, C. & Christensen, U.R., 2002. From stable dipolar towards reversing numerical dynamos, Phys. Earth. planet. Inter., 131, 29-45.
53. Langlais, B., Mandea, M. & Ultre-Guerard, P., 2003. High resolution magnetic field modelling: application to MAGSAT and Ørsted data, Phys. Earth. planet. Inter., 135, 77-91.
54. LeMouël, J.L., 1984. Outer core geostrophic flow and secular variation of Earth's magnetic field, Nature, 311, 734-735.
55. Lesur, V., Wardinski, I., Rother, M. & Mandea, M., 2008. GRIMM: the GFZ reference internal magnetic model based on vector satellite and observatory data, Geophys. J. Int., 173, 382-394.
56. Lesur, V., Wardinski, I., Asari, S., Minchev, B. & Mandea, M., 2010. Modelling the Earth's core magnetic field under flow constraints, Earth, Planets Space, 10, 503-516.
57. Lloyd, D. & Gubbins, D., 1990. Toroidal fluid motion at the top of Earth's core, Geophys. J. Int., 100, 455-467.
58. Lowes, F.J., 1966. Mean-square values on the sphere of spherical harmonic vector fields, J. geophys. Res., 71, 2179.
59. Lowes, F.J., 1974. Spatial power spectrum of the main geomagnetic field, Geophys. J. R. astr. Soc., 36, 717-730.
60. Mason, J., Cattaneo, F. & Boldyrev, S., 2006. Dynamic alignment in driven magnetohydrodynamic turbulence, Phys. Rev. Lett., 97, 255002, doi:.
61. Mauersberger, P., 1956. Das mittel der energiedichte des geomagnetischen hauptfeldes and der erderflaeche unde seine saekulare anderung, Anderung, Gerlands Beitr. Geophys., 65, 207-215.
62. McLeod, M.G., 1996. Spatial and temporal power spectra of the geomagnetic field, J. geophys. Res, 101, B2, 2745-2763.
63. Moffatt, H.K., 1978. Magnetic Field Generation in Electrically Conducting Fluids, Cambridge Univeristy Press, Cambridge.
64. Nagata, T. & Syono, Y., 1961. Geomagnetic secular variation during the period from 1955 to 1960, J. Geomagnet. Geoelec., 12, 84-98.
65. Olsen, N. & Mandea, M., 2008. Rapidly changing flows in the Earth's core, Nat. Geosci., 1, 390-394.
66. Olsen, N., Lühr, H., Sabaka, T.J., Mandea, M., Rother, M., Tøffner-Clausen, L. & Choi, S., 2006. CHAOS: a model of the Earth's magnetic field derived from CHAMP, Ørsted and SAC-C magnetic satellite data, Geophys. J. Int., 166, 67-75.
67. Olson, P. & Christensen, U.R., 2002. The time averaged magnetic field in numerical dynamos with nonuniform boundary heat flow, Geophys. J. Int., 151, 809-823.
68. Olson, P. & Christensen, U.R., 2006. Dipole moment scaling for convection-driven planetary dynamos, Earth planet. Sci. Lett., 250, 561-571.
69. Olson, P., Christensen, U.R. & Glatzmaier, G.A., 1999. Numerical modeling of the geodynamo: mechanisms of field generation and equilibration, J. geophys. Res., 104, 10383-10404.
70. Olson, P., Sumita, I. & Aurnou, J., 2002. Diffusive magnetic images of core upwellings, J. geophys. Res., 107, doi:.
71. Pais, M.A. & Jault, D., 2008. Quasi-geostrophic flows responsible for the secular variation of the Earth's magnetic field, Geophys. J. Int., 173, 421-443.
72. Pais, M.A., Oliveira, O. & Nogueira, F., 2004. Nonuniqueness of inverted core-mantle boundary flows and deviations from tangential geostrophy, J. geophys. Res., 109, B08105, doi:.
73. Perez, J.C. & Boldyrev, S., 2007. Role of cross-helicity in magnetohydrodynamic turbulence, Phys. Rev. Lett., 102, 025003, doi:.
74. Poirier, J.P., 2000. Introduction to the Physics of the Earth's Interior, Cambridge University Press, Cambridge .
75. Ponty, Y., Politano, H. & Pinton, J.F., 2004. Simulation of induction at low magnetic Prandtl number, Phys. Rev. Lett., 92, 1144503, doi:.
76. Rau, S., Christensen, U.R., Jackson, A. & Wicht, J., 2000. Core flow inversion tested with numerical dynamo models, Geophys. J. Int., 141, 485-497.
77. Roberts, P.H. & Glatzmaier, G.A., 2000. A test of the frozen flux approximation using a new geodynamo model, Phil. Trans. R. Soc. Lond. A., 358, 1109-1121.
78. Roberts, P.H. & Scott, S., 1965. On analysis of the secular variation, 1, a hydromagnetic constraint: theory, J. Geomagn. Geoelectr., 17, 137-151.
79. Roberts, P.H., Jones, C.A. & Calderwood, A.R., 2003. Energy fluxes and ohmic dissipation in the Earth's core, in Earth's Core and Lower Mantle, eds Jones, C., Soward, A. & Zhang, K., Taylor and Francis, London .
80. Schaeffer, N. & Cardin, P., 2006. Quasi-geostrophic kinematic dynamos at low magnetic Prandtl number, Earth planet. Sci. Lett., 245, 595-604.
81. Schrinner, M., Schmitt, D., Cameron, R. & Hoyng, P., 2010. Saturation and time dependence of geodynamo models, Geophys. J. Int., 182, 675-681.
82. Secco, R.A. & Schloessin, H.H., 1989. The electrical resistivity of solid and Fe at pressures up to 7 GPa, J. geophys. Res., 94, 5887-5894.
83. Sreenivasan, B. & Jones, C.A., 2006. The role of inertia in the evolution of spherical dynamos, Geophys. J. Int., 164, 467-476.
84. Stacey, F.D., 1992. Physics of the Earth, Brookfield Press, Brisbane.
85. Stacey, F.D. & Loper, D.E., 2007. A revised estimate of the conductivity of iron alloy at high pressure and implications for the core energy balance, Phys. Earth planet. Int., 161, 13-18.
86. Stevenson, D.J., 1983. Planetary magnetic fields, Rep. Prog. Phys., 46, 555-620.
87. Takahashi, F. & Matsushima, M., 2005. Dynamo action in a rotating spherical shell at high Rayleigh numbers, Phys. Fluids, 17, 076601, doi:.
88. Takahashi, F., Matsushima, M. & Honkura, Y., 2008. Scale variability in convection-driven MHD dynamos at low Ekman number, Phys. Earth planet. Inter., 167, 168-178.
89. Vestine, E.H., Laporte, L., Cooper, C., Lange, I. & Hendrix, W.C., 1947. Description of the Earth's Main Magnetic Field and its Secular Change, Carnegie Institution Publ., Washington, DC .
90. Voorhies, C.V., 1986. Steady flows at the top of Earth's core derived from geomagnetic field models, J. geophys. Res., 91, 12444-12466.
91. Voohries, C.V., 2004. Narrow-scale flow and a weak field by the top of Earth's core: evidence from Ørsted, magsat and secular variation, J. geophys. Res., 109, B03106, doi:.
92. Voohries, C.V., Sabaka, T.J. & Purucker, M., 2002. On magnetic spectra of Earth and Mars, J. geophys. Res., 107, 5034, doi:.
93. Wardinski, I., Holme, R., Asari, S. & Mandea, M., 2008. The 2003 geomagnetic jerk and its relation to core surface flows, Earth planet. Sci. Lett., 267, 468-481.
94. Whaler, K.A., 1980. Does the whole of Earth's core convect? Nature, 287, 528-530.
95. Whaler, K. & Holme, R., 2007. Consistency between flow at the top of the core and the frozen-flux approximation, Earth, Planets, Space, 1, 1219-1259.
96. Wicht, J., 2002. Inner-core conductivity in numerical dynamo simulations, Phys. Earth planet. Inter., 132, 281-302.
97. Wicht, J. & Tilgner, A., 2010. Theory and modeling of planetary dynamos, Space Sci. Rev., 152, doi:.