Energetics of the Earth's core

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D. Gubbins


The energy supplied to generate the Earth's magnetic field must ultimately result in heat flowing across the core-mantle boundary and through the Earth's surface. If the liquid core is stirred by thermal convection then only a small fraction of the total heat is dissipated in the electric currents, and in order to explain the observed field at least 1011 watt and probably 1013 watt of the Earth's surface heat flux must originate deep inside the core. If the core is cooling and there is concomitant chemical differentiation, a large amount of gravitational energy is released. This energy, unlike the heat released, is completely dissipated in the electric currents and enables the same magnetic field to be generated with a much lower heat flux. Chemical differentiation is therefore favoured as the energy source for the dynamo. The importance of gravitational settling depends on the density jump at the inner core boundary and on the stratification parameter in the outer core, both of which can, in principle, be determined seismologically.

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Gubbins, D. (1977). Energetics of the Earth’s core. Journal of Geophysics, 43(1), 453-464. Retrieved from https://journal.geophysicsjournal.com/JofG/article/view/64
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