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Numerical dynamo simulations reproduce palaeomagnetic field behaviour
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  • Domenico G. Meduri,
  • Andrew J. Biggin,
  • Christopher J. Davies,
  • Richard K. Bono,
  • Courtney J. Sprain,
  • Johannes Wicht
Domenico G. Meduri
University of Liverpool, University of Liverpool

Corresponding Author:[email protected]

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Andrew J. Biggin
University of Liverpool, University of Liverpool
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Christopher J. Davies
University of Leeds, University of Leeds
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Richard K. Bono
University of Liverpool, University of Liverpool
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Courtney J. Sprain
University of Florida, University of Florida
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Johannes Wicht
Max Planck Institute for Solar System Research, Max Planck Institute for Solar System Research
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Abstract

Numerical geodynamo simulations capture several features of the spatial and temporal geomagnetic field variability on historical and Holocene timescales. However, a recent analysis questioned the ability of these numerical models to comply with long-term palaeomagnetic field behaviour. Analysing a suite of 50 geodynamo models, we present here the first numerical simulations known to reproduce the salient aspects of the palaeosecular variation and time-averaged field behaviour since 10 Ma. We find that the simulated field characteristics covary with the relative dipole field strength at the core-mantle boundary (dipolarity). Only models dominantly driven by compositional convection, with an Ekman number (ratio of viscous to Coriolis forces) lower than $10^{-3}$ and a dipolarity in the range $0.34-0.56$ can capture the observed palaeomagnetic field behaviour. This dipolarity range agrees well with state-of-the-art statistical field models and represent a testable prediction for next generation global palaeomagnetic field model reconstructions.