A Coupled Map Lattice model for geomagnetic polarity reversals that exhibits realistic scaling

Abstract

Seki and Ito (1993) showed that the geomagnetic polarity reversals had a power-law distribution and presented a simple model in which the geodynamo was assumed to be a system of magnetic spins in a critical phase-transition state. We present an improved, more realistic model, and obtain a power exponent in agreement with the observed value, which is about −1.5. The revised model is a Coupled Map Lattice (CML). A CML is a dynamical system with discrete time and space, but continuous state. In the present model, elementary dynamo evolves autonomously according to the Lorenz map obtained from Rikitake dynamo dynamics. We examine the behavior of the system and the distribution of polarity reversal intervals for various values of parameters. We find some sets of the parameters which yield a power exponent close to −1.5.