A paleomagnetic power spectrum

We construct a power spectrum of geomagnetic dipole moment variations or their proxies that spans the period range from some tens of million down to about 100 years. Empirical estimates of the spectrum are derived from the magnetostratigraphic time scale, from marine sediment relative paleointensity...

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Bibliographic Details
Published in:Physics of the earth and planetary interiors 2005-11, Vol.153 (1), p.61-73
Main Authors: Constable, Catherine, Johnson, Catherine
Format: Article
Language:English
Subjects:
Geomagnetism
Paleomagnetic power spectrum
Paleomagnetism
Paleosecular variations
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Summary:We construct a power spectrum of geomagnetic dipole moment variations or their proxies that spans the period range from some tens of million down to about 100 years. Empirical estimates of the spectrum are derived from the magnetostratigraphic time scale, from marine sediment relative paleointensity records, and from a time varying paleomagnetic field model for the past 7 kyr. The spectrum has the most power at long periods, reflecting the influence of geomagnetic reversals and in general decreases with increasing frequency (decreasing period). The empirical spectrum is compared with predictions from simple models. Discrepancies between the observed and predicted spectra are discussed in the context of: (i) changes in reversal rate, (ii) overall average reversal rate, (iii) cryptochrons, (iv) the time taken for a reversal to occur, and (v) long term paleosecular variations and average estimates of the field strength and variance from other sources.
ISSN:0031-9201
1872-7395
DOI:10.1016/j.pepi.2005.03.015