Magnetostrophic Turbulence and the Geodynamo

  • H. Keith Moffatt
Part of the IUTAM Bookseries book series (IUTAMBOOK, volume 4)


The flow generated by a random buoyancy field in a rotating medium permeated by a dynamo-generated magnetic field is considered, under the assumptions that the Rossby number and the magnetic Reynolds number (based on the scale of the buoyancy fluctuations) are both small. This permits linearisation of the governing evolution equations. Provided ‘up-down’ symmetry is broken, a mean helicity and an associated α-effect are generated. These are calculated in terms of the spectrum function of the buoyancy field. Expressions are also obtained for the buoyancy flux and the Reynolds stresses (kinetic and magnetic), and an outline dynamo scenario is proposed. The nature of this type of magnetostrophic turbulence is briefly discussed.


magnetostrophic geodynamo helicity α-effect mean-field theory 


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Copyright information

© Springer 2008

Authors and Affiliations

  • H. Keith Moffatt
    • 1
  1. 1.Department of Applied Mathematics and Theoretical PhysicsUniversity of CambridgeCambridgeUK

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