Core-mantle driving in geodynamo models

Principal investigators: Dr C Davies

Sponsor: NERC

Value: £232,735

Dates: 31/03/2011 - 30/03/2014

Summary

Earth's magnetic field is generated in the outer core by the so-called geodynamo mechanism, where motions of an electrically conducting fluid provide the inductive action to sustain the field against dissipative effects. Observations of the magnetic field reveal a rich variety of spatio-temporal  behaviour; understanding the processes operating in the outer core that give rise to this behaviour is one of the outstanding challenges in Earth science. Current geodynamo simulations produce large-scale magnetic fields that bear striking similarities to the observed field, but use unrealistic parameters with the consequence that fields are generated by large-scale flows. Small-scale flows will emerge at more realistic parameters; it is not known how such flows will generate the large-scale features seen in observations. My previous work using models of non-magnetic convection has highlighted a physical process that has the potential to promote persistent large-scale features in Earth-like parameter regimes: lateral variations of heat flow from the core to mantle cause small-scale flows to coalesce into large-scale structures, a process I call clustering. In this research I will use this hypothesis and a multidisciplinary approach that integrates seismic and geomagnetic observations to understand the clustering process and exploit the results with the aim of developing geodynamo models that produce realistic magnetic fields by a realistic mechanism.