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Constructing Stochastic Models for Dipole Fluctuations from Paleomagnetic Observations

Buffett, Bruce and Puranam, Abhijit (2017) Constructing Stochastic Models for Dipole Fluctuations from Paleomagnetic Observations. Physics of the Earth and Planetary Interiors, 272 . pp. 68-77. ISSN 0031-9201. doi:10.1016/j.pepi.2017.09.001.

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Records of relative paleointensity are subject to several sources of error. Temporal averaging due to gradual acquisition of magnetization removes high-frequency fluctuations, whereas random errors introduce fluctuations at high frequency. Both sources of error limit our ability to construct stochastic models from paleomagnetic observations. We partially circumvent these difficulties by recognizing that the largest affects occur at high frequency. To illustrate we construct a stochastic model from two recent inversions of paleomagnetic observations for the axial dipole moment. An estimate of the noise term in the stochastic model is recovered from a high-resolution inversion (CALS10k.2), while the drift term is estimated from the low-frequency part of the power spectrum for a long, but lower-resolution inversion (PADM2M). Realizations of the resulting stochastic model yield a composite, broadband power spectrum that agrees well with the spectra from both PADM2M and CALS10k.2. A simple generalization of the stochastic model permits predictions for the mean rate of magnetic reversals. We show that the reversal rate depends on the time-averaged dipole moment, the variance of the dipole moment and a slow timescale that characterizes the adjustment of the dipole toward the time-averaged value. Predictions of the stochastic model give a mean rate of 4.2 Myr^(−1), which is in good agreement with observations from marine magnetic anomalies.

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Additional Information:© 2017 Elsevier B.V. Received 18 March 2017, Revised 15 August 2017, Accepted 1 September 2017, Available online 5 September 2017. This work is supported by the National Science Foundation (EAR-1644644) and by a Summer Undergraduate Research Fellowship (SURF) from Caltech.
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Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
Subject Keywords:Geodynamo; Geomagnetic spectrum; Stochastic model
Record Number:CaltechAUTHORS:20170905-130421308
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Official Citation:Bruce Buffett, Abhijit Puranam, Constructing stochastic models for dipole fluctuations from paleomagnetic observations, In Physics of the Earth and Planetary Interiors, Volume 272, 2017, Pages 68-77, ISSN 0031-9201, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81138
Deposited By: Ruth Sustaita
Deposited On:05 Sep 2017 20:35
Last Modified:15 Nov 2021 19:41

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