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Lookup NU author(s): David Ryan,
Dr Graeme Sarson
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We consider geomagnetic field reversal sequences from the last 160 Ma, and find the inter-reversal times to be well fit by a lognormal distribution. Such a distribution could arise from 'multiplicative noise' in the underlying geodynamo; and turbulent fluctuations within the core may be expected to provide such noise via the α-effect of dynamo theory. We investigate this mechanism by coupling a low order αω-type dynamo to a shell model of turbulence. This model reproduces field reversals varying in duration from subchrons to superchrons; these are reasonably fit by a lognormal distribution, consistent with the multiplicative noise mechanism proposed. Copyright 2007 by the American Geophysical Union.
Author(s): Ryan DA, Sarson GR
Publication type: Article
Publication status: Published
Journal: Geophysical Research Letters
ISSN (print): 0094-8276
ISSN (electronic): 1944-8007
Publisher: American Geophysical Union
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