On the ill/well-posedness and nonlinear instability of the magneto-geostrophic equations

Susan Friedlander, Vlad Vicol

Research output: Contribution to journalArticle


We consider an active scalar equation that is motivated by a model for magneto-geostrophic dynamics and the geodynamo. We prove that the non-diffusive equation is ill-posed in the sense of Hadamard in Sobolev spaces. In contrast, the critically diffusive equation is globally well-posed (cf Friedlander and Vicol (2011 Ann. Inst. Henri Poincaré Anal. Non Linéaire 28 283-301)). In this case we give an example of a steady state that is nonlinearly unstable, and hence produces a dynamo effect in the sense of an exponentially growing magnetic field.

Original languageEnglish (US)
Pages (from-to)3019-3042
Number of pages24
Issue number11
StatePublished - Nov 1 2011


ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Mathematical Physics
  • Physics and Astronomy(all)
  • Applied Mathematics

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