Title of article :
On the effect of an electrically heterogeneous lower mantle on planetary dynamos
Author/Authors :
Chan، نويسنده , , Kit H. and Zhang، نويسنده , , Keke and Li، نويسنده , , Ligang and Liao، نويسنده , , Xinhao، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2008
Abstract :
Self-consistent convection-driven dynamos in an electrically conducting fluid spherical shell of constant electric conductivity surrounded by an electrically heterogeneous lower mantle are investigated using an element-by-element finite element method that takes the full advantage of modern massively parallel computers. The primary objective is to explore possible effects of an electrically heterogeneous mantle on the self-consistent convection-driven dynamos in rotating spherical systems. The dynamo solutions obtained with an electrically heterogeneous mantle are compared to that obtained with a uniformly insulating mantle at exactly the same Rayleigh, Ekman and Prandtl numbers. Three important effects are identified: (i) an electrically heterogeneous mantle can induce a vacillating dynamo whose amplitude is determined by the relative phase between the time-dependent dynamo solution and the electrically heterogeneous mantle, (ii) the spatial structure of the radial component of the generated magnetic field in the vicinity of the core–mantle boundary, an observable component of planetary magnetic fields, is strongly influenced by the structure of the electrically heterogeneous lower mantle and (iii) the extra magnetic dissipation taking place in a very thick electrically conducting layer in lower mantle can terminate dynamo action operating in the fluid core.
Keywords :
Electrically heterogeneous mantle , Convection , Finite element method , Dynamos
Journal title :
PHYSICS OF THE EARTH AND PLANETARY INTERIORS
Journal title :
PHYSICS OF THE EARTH AND PLANETARY INTERIORS