Nonuniqueness of inverted core-mantle boundary flows and deviations from tangential geostrophy

Journal of Geophysical Research: Solid Earth

Volumn 109, Issue 8, 2004, Pages

  Pais, M A ^a   Oliveira, O ^a   Nogueira, F ^a  

^a UNIVERSITY OF COIMBRA   (Portugal)

Author keywords

CMB electrical density currents; CMB flows; Tangential geostrophy

Indexed keywords

CORE-MANTLE BOUNDARY; FLOW MODELING; GEOMAGNETIC FIELD; GEOSTROPHIC FLOW;

EID: 7044241348     PISSN: 21699313     EISSN: 21699356     Source Type: Journal    
DOI: 10.1029/2004JB003012     Document Type: Article

References (40)

1. Backus, G. E. (1968), Kinematics of geomagnetic secular variation in a perfectly conducting core, Philos. Trans. R. Soc. London, Ser A, 263, 239-266.
2. Backus, G. E., and J.-L. Le Mouël (1986), The region on the core-mantle boundary where a geostrophic velocity field can be determined from frozen-flux magnetic data, Geophys. J R. Astron. Soc., 85, 617-628.
3. Benton, E. R., and L. A. Muth (1979), On the strength of electric currents and zonal magnetic fields at the top of the Earth's core: Methodology and preliminary estimates, Phys. Earth Planet. Inter., 20, 127-133.
4. Bloxham, J. (1988), The dynamical regime of fluid flow at the core-mantle boundary, Geophys. Res. Lett., 15, 585-588.
5. Bloxbam, J. (1989), Simple models of fluid flow at the core surface determined from geomagnetic field models, Geophys. J. Int., 141, 173-182.
6. Bloxham, J. (1990), On the consequences of strong stable stratification at the top of the Earth's outer core, Geophys. Res. Lett., 17, 2081-2084.
7. Bloxham, J., and A. Jackson (1991), Fluid flow near the surface of Earth's outer core, Rev. Geophys., 29, 97-120.
8. Bloxham, J., and A. Jackson (1992), Time-dependent mapping of the magnetic field at the core-mantle boundary, J. Geophys. Res., 97, 19,537-19,563.
9. Braginsky, S. I. (1970), Torsional magnetohydrodynamic vibrations in the Earth's core and variations in day length, Geomag. Aeron., Engl. Transl., 10, 1-8.
10. Braginsky, S. I. (1999), Dynamics of the stably stratified ocean at the top of the core, Phys. Earth Planet. Inter., 111, 21-34.
11. Buffett, B. A. (2000), Dynamics of the Earth's core, in Earth's Deep Interior: Mineral Physics and Tomography From the Atomic to the Global Scale, Geophys. Monogr Ser, vol. 117, edited by S. Karato et al., pp. 37-62, AGU, Washington, D. C.
12. Chulliat, A., and G. Hulot (2000), Local computation of the geostrophic pressure at the top of the core, Phys. Earth Planet. Inter., 117, 309-328.
13. Dormy, E., J.-P. Valet, and V. Courtillot (2000), Numerical models of the geodynamo and observational constraints, Geochem. Geophys. Geosyst., 1, Paper number 2000GCO00062.
14. Drecker, A., G. Rüdiger, and R. Hollerbach (2000), Global structure of self-excited magnetic fields arising from the magnetic shear instability, Mon. Not. R. Astron. Soc., 317, 45-54.
15. Gire, C., and J.-L. Le Mouël (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.
16. Gubbins, D. (1982), Finding core motions from magnetic observations, Philos. Trans. R. Soc. London, Ser. A, 306, 247-254.
17. Gubbins, D., and P. H. Roberts (1987), Magnetohydrodynamics of the Earth's core, in Geomagnetism, vol. 2, edited by J. A. Jacobs, pp. 1-183, Academic, San Diego, Calif.
18. Gubbins, D., D. Alfè, G. Masters, G. D. Price, and M. J. Gillan (2003), Can the Earth's dynamo run on heat alone?, Geophys. J Int., 155, 609-622.
19. Hills, R. G. (1979), Convection in the Earth's mantle due to viscous shear at the core-mantle interface and due to large-scale buoyancy, Ph.D. thesis, N. M. State Univ., Las Cruces.
20. Holme, R. (1998a), Electromagnetic core-mantle coupling: I. Explaining decadal changes in the length of day, Geophys. J. Int., 132, 167-180.
21. Holme, R. (1998b), Electromagnetic core-mantle coupling: II. Probing deep mantle conductance, in The Core-Mantle Boundary Region, Geodyn. Ser, vol. 28, edited by M. Gurnis, M. E. Wysession, E. Knittle, and B. A. Buffett, pp. 139-151, AGU, Washington, D. C.
22. Hulot, G., M. L. Huy, and J.-L. L. Mouël (1993), Secousses (jerks) de la variation séculaire et mouvements dans le noyau terrestre, C. R. Acad. Sci., Ser A, 317, 333-341.
23. Hulot, G., C. Eymin, B. Langlais, M. Mandea, and N. Olsen (2002), Smallscale structure of the geodynamo inferred from Oersted and Magsat satellite data, Nature, 416, 620-623.
24. Jackson, A. (1997), Time-dependency of tangentially geostrophic core surface motions, Phys. Earth Planet. Inter., 103, 293-311.
25. Jackson, A., J. Bloxham, and D. Gubbins (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, Geophys. Monogr. Ser., vol. 72, edited by J.-L. L. Mouël, D. E. Smylie, and T. A. Herring, pp. 97-107, AGU, Washington, D. C.
26. Jault, D., and J.-L. Le Mouël (1991), Physical properties at the top of the core and core surface motions, 68, 76-84.
27. Jault, D., C. Gire, and J.-L. L. Mouël (1988), Westward drift, core motions and exchanges of angular momentum between core and mantle, Nature, 333, 353-356.
28. Labrosse, S. (2003), Thermal and magnetic evolution of the Earth's core, Phys. Earth Planet. Inter, 140, 127-143.
29. Le Mouël, J.-L. (1984), Outer core geostrophic flow and secular variation of Earth's magnetic field, Nature, 311, 734-735.
30. Le Mouël, J.-L., C. Gire, and T. Madden (1985), Motions at core surface in the geostrophic approximation, Phys. Earth Planet. Inter., 39, 270-287.
31. Love, J. J. (1999), A critique of frozen-flux inverse modelling of a nearly steady geodynamo, Geophys. J. Int., 138, 353-365.
32. Madden, T., and J.-L. Le Mouël (1982), The recent secular variation and the motions at the core surface, Philos. Trans. R. Soc. London, 306, 271-280.
33. Mosegaard, K., and C. Rygaard-Hjalsted (1999), Probabilistic analysis of implicit inverse problems, Inverse Problems, 15, 573-583.
34. Pais, A., and G. Hulot (2000), Length of day decade variations, torsional oscillations and inner core superrotation: Evidence from recovered core surface zonal flows, Phys. Earth Planet. Inter., 118, 291-316.
35. Rau, S., U. Christensen, A. Jackson, and J. Wicht (2000), Core flow inversion tested with numerical dynamo models, Geophys. J. Int., 141, 485-497.
36. Roberts, P. H., and S. Scott (1965), On analysis of the secular variation, J. Geomagn. Geoelectr., 17, 137-151.
37. Rygaard-Hjalsted, C., K. Mosegaard, and N. Olsen (2000), Resolution studies of fluid flow models near the core-mantle boundary through bayesian inversion of geomagnetic data, in Methods and Applications of Inversion, Lect. Notes Earth Sci., vol. 92, edited by C. Hansen, B. Jacobsen, and K. Mosegaard, pp. 255-275, Springer-Verlag, New York.
38. Voorhies, C. V. (1995), Time-varying fluid flow at the top of Earth's core derived from definitive geomagnetic reference field models, J. Geophys. Res., 100, 10,029-10,039.
39. Voorhies, C. V., and G. E. Backus (1985), Steady flows at the top of the from geomagnetic field models: The steady motions theorem, Geophys. Astrophys. Fluid Dyn., 32, 163-173.
40. Whaler, K. A. (1980), Does the whole of the Earth's core convect?, Nature, 287, 528-530.