# Evidence for crisis-induced intermittency during geomagnetic superchron transitions

## TL;DR

This paper presents observational and modeling evidence that geomagnetic superchron transitions involve crisis-induced intermittency, characterized by increased non-Gaussianity and moments, indicating underlying bifurcations in Earth's magnetic field dynamics.

## Contribution

It provides the first observational evidence linking geomagnetic superchron transitions to crisis-induced intermittency and models this process with a low-dimensional system.

## Key findings

- High non-Gaussianity near superchron transitions
- Increase in skewness and kurtosis during transitions
- Destruction of global periodic orbits in the model

## Abstract

The geomagnetic field's dipole undergoes polarity reversals in irregular time intervals. Particularly long periods (of the order of $10^7$yrs) without reversals, named superchrons, have occurred at least three times in history. We provide observational evidence for high non-Gaussianity in the vicinity of a transition to and from a geomagnetic superchron, consisting of a sharp increase in high-order moments (skewness and kurtosis) of the dipole's distribution. Such increase in the moments is a universal feature of crisis-induced intermittency in low-dimensional dynamical systems undergoing global bifurcations. This suggests temporal variation of the underlying parameters of the physical system. Through a low dimensional system that models the geomagnetic reversals we show that the increase in the high-order moments during transitions to geomagnetic superchrons is caused by the progressive destruction of global periodic orbits exhibiting both polarities as the system approaches a merging bifurcation. We argue that the non-gaussianity in this system is caused by the redistribution of the attractor around local cycles as global ones are destroyed.