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| Titel |
Numerical study on the thermo-chemically driven Geodynamo |
| VerfasserIn |
Tobias Trümper, Ulrich Hansen |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250100086
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| Publikation (Nr.) |
 EGU/EGU2014-15970.pdf |
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| Zusammenfassung |
| In our numerical study we consider magneto-convection in the Earth’s outer core driven by
buoyancy induced by heterogeneities both in the thermal and the chemical field. The outer
core is thus treated as a self-gravitating, rotating, spherical shell with unstable thermal and
chemical gradients across its radius. The thermal gradient is maintained by secular cooling of
the core and the release of latent heat at the inner core freezing front. Simultaneously, the
concentration of the light constituents of the liquid phase increases at the inner core boundary
since only a smaller fraction of the light elements can be incorporated during solidification.
Thus, the inner core boundary constitutes a source of compositional buoyancy. The
molecular diffusivities of the driving agents differ by some orders of magnitude so
that a double-diffusive model is employed in order to study the flow dynamics
of this system. We investigate the influence of different thermo-chemical driving
scenarios on the structure of the flow and the internal magnetic field. A constant ratio of
the diffusivities (Le=10) and a constant Ekman number (Ek=10-4) are adopted.
Apart from testing different driving scenarios, the double-diffusive approach also
allows to implement distinct boundary conditions on temperature and composition.
Isochemical and fixed chemical flux boundary conditions are implemented in order to
investigate their respective influence on the flow and magnetic field generation. |
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