A convection driven geodynamo reversal model

Details A convection driven geodynamo reversal model A convection driven geodynamo reversal model

Feb 1999

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999pepi..111....3s&link_type=abstract

Physics of the Earth and Planetary Interiors, Volume 111, Issue 1-2, p. 3-20.

Physics

64

Scientific paper

A convection driven geodynamo model, with a dominantly dipolar field which intermittently reverses polarity, is described. The model employs the two-mode approximation introduced by Jones et al. [Jones, C.A., Longbottom, A.W., Hollerbach, R., 1995. A self-consistent convection driven geodynamo model, using a mean field approximation, Phys. Earth Planet. Int., 92, 119-141] nevertheless, it exhibits many similarities to the fully three-dimensional models of Glatzmaier and Roberts [Glatzmaier, G.A., Roberts, P.H., 1995b. A three-dimensional convective dynamo solution with rotating and finitely conducting inner core and mantle, Phys. Earth Planet. Int., 91, 63-75 Glatzmaier, G.A., Roberts, P.H., 1996a. An anelastic evolutionary geodynamo simulation driven by compositional and thermal convection, Physica D, 97, 81-94]. The velocity field is dominated by a `thermal wind' structure throughout, with this form of flow favouring the production of an essentially steady dipolar field. A decrease in the meridional circulation of this flow leads to a preference for oscillatory fields. Dynamical fluctuations in this part of the flow may therefore initiate episodes of field reversal, thus constituting a simple kinematic reversal mechanism. This mechanism is consistent with a numerical reversal sequence studied, where intermittent fluctuations in the meridional component of the thermal wind velocity, associated with `buoyancy surges', are observed. Both our solutions and the comparable three-dimensional solutions are dominated by similar axisymmetric fields, suggesting that nonlinear interactions giving rise to higher wavenumbers are here of secondary importance. The magnetic field plays a surprisingly small role in the dynamics, viscosity retaining an important role. The use of hyperdiffusivities, employed as a parameterisation of the small-scale diffusion beyond our resolution, appears to contribute towards both these features. Nevertheless, the essential axisymmetric features of the solution, related to rather simple physical mechanisms, constitute a feasible model for the reversing geodynamo.

Affiliated with

Also associated with

No associations

Rating

A convection driven geodynamo reversal model does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with A convection driven geodynamo reversal model, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A convection driven geodynamo reversal model will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-949114