HR: 0800h
AN: NG31A-0864    [Abstracts]
TI: Stochastic Resonance In The Rikitake Dynamo: An Implication For The Relationship Between Geomagnetic Reversal And Glacial Events
AU: * Chen, C
EM: chencc@earth.ncu.edu.tw
AF: Inst. Geophys., Nat'l Central Univ., No.300, Jhongda Rd., Jhongli, 320 Taiwan
AU: Tseng, C
EM: richard@pooh.phy.ncu.edu.tw
AF: Dept. Phys., Nat'l Central Univ., No.300, Jhongda Rd., Jhongli, 320 Taiwan
AB: Not yet a theoretical analysis can explain the coincident temporal correlation between the geomagnetic reversal and glacial events, which both have a quasi-period of about 100 kyr, although there exists dozens of observational evidences for such correlation. In this work, by simulating the behavior of a simple Rikitake dynamo subject to an external periodic force, we show a series of quasi-periodic polarity reversals can be embedded in the geomagnetic filed via the mechanism of stochastic resonance. The term of "stochastic resonance" describes the group of effects in nonlinear system, whereby the response of the system to the weak external, periodic signal is remarkably amplified by the increase of noise intensity. We consequently suggest a common triggering mechanism for the geomagnetic reversal and glacial events, neither the glacial epoch controls the geomagnetic epoch nor vice versa. Instead, both kinds of catastrophes may result from the cyclic variation of the Earth's orbital eccentricity. Our demonstration of stochastic resonance in the Rikitake dynamo thus provides the first theoretical evidence for the relationship between two kinds of catastrophes, the geomagnetic reversal and glacial events, in the Earth's history.
DE: 3220 Nonlinear dynamics
DE: 3230 Numerical solutions
DE: 1510 Dynamo theories
DE: 1535 Reversals (process, timescale, magnetostratigraphy)
SC: Nonlinear Geophysics [NG]
MN: 2004 AGU Fall Meeting