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| INFLUENCE OF THE EARTHS INNER-CORE ON GEOMAGNETIC FLUCTUATIONS AND REVERSALS |
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| Author(s): HOLLERBACH R, JONES CA |
| Source: NATURE Volume: 365 Issue: 6446 Pages: 541-543 Published: OCT 7 1993 |
| Times Cited: 137 References: 17 |
| Abstract: IN view of its relatively small size (one-third the radius of the outer core), many geodynamo models neglect the inner core entirely1, or otherwise treat it as a non-conducting insulator2,3. In a previous steady-state model4, we considered some effects of a finitely conducting inner core, in particular the resulting electromagnetic coupling between inner and outer core. Here we include a prescribed buoyancy force, which is geophysically more realistic, and also yields time-dependent rather than time-independent solutions. The field in the finitely conducting inner core does not then adjust instantaneously to the field in the outer core, but has a diffusive timescale of its own of a few thousand years. Rather large, rapid fluctuations in the outer core are then effectively averaged out by the inner core, producing a relatively stable external dipole field. We speculate that a geomagnetic reversal could only occur as a result of a particularly large fluctuation, large enough and lasting long enough to reverse the field throughout the inner core as well. |
| Document Type: Article |
| Language: English |
| Reprint Address: HOLLERBACH, R (reprint author), UNIV EXETER, DEPT MATH, EXETER EX4 4QE, ENGLAND |
| Publisher: MACMILLAN MAGAZINES LTD, PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW |
| Subject Category: Multidisciplinary Sciences |
| IDS Number: MA661 |
| ISSN: 0028-0836 |
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