Insights into pre-reversal paleosecular variation from stochastic models

Abstract

To provide insights on the paleosecular variation of the geomagnetic field and the mechanism of reversals, long time series of the dipolar magnetic moment are generated by two different stochastic models, known as the "domino" model and the inhomogeneous Lebovitz disk dynamo model, with initial values taken from the paleomagnetic data. The former model considers mutual interactions of N macrospins embedded in a uniformly rotating medium, where random forcing and dissipation act on each macrospin. With an appropriate set of the model's parameter values, the series generated by this model have similar statistical behavior to the time series of the SHA.DIF.14K model. The latter model is an extension of the classical two-disk Rikitake model, considering N dynamo elements with appropriate interactions between them. We varied the parameters set of both models aiming at generating suitable time series with behavior similar to the long time series of recent secular variation (SV). Such series are then extended to the near future, obtaining reversals in both cases of models. The analysis of the time series generated by simulating both the models show that the reversals appear after a persistent period of low intensity geomagnetic field.

The multifractality of the internal geomagnetic field

“…Interestingly there is observed a mild anti-persistence in which is directed to random walk-like values when the magnitude of the moment reaches near zero. Such occurrences pertain to reversals [1,2,3,13,14,15] indicating a possible connection which begs further investigations. Figure 5.…”