Thermal and magnetic constraints on the cooling of the Earth

Abstract

The thermodynamic requirements of a dynamo in the Earth's core can be expressed in terms of the heat flux from core to mantle. That heat flux is estimated from a simple layered model of the Earth, using parameterized convection theory to calculate the heat transport through the mantle. The model conforms to two thermal constraints: that the radius of the inner core and the heat flux to the surface at the present time should be equal to those observed on Earth. Resulting values for the heat flux from core to mantle are compared with the dynamo requirements and it is shown that, even in the absence of a ‘gravitational drive', the heat flux can be sufficient to power the dynamo both before and after the formation of the inner core, for a wide range of currently accepted values of the Earth's parameters. Copyright © 1984, Wiley Blackwell. All rights reserved