Abstract
Magnetic polarity transitions in a Takahashi-Matsushima-Honkura dynamo model are analyzed. Distinctive differences in behavior of the axisymmetric poloidal magnetic field are found among a polarity reversal and excursions, including short polarity events. At the beginning of magnetic polarity transitions, the magnetic field with the reversed polarity is generated by anti-cyclonic convection columns deep within the outer core. In the case of excursion, it is soon advected by the radial flow toward a shallow interior of the core, and the transition can be detected at the core surface. However, the same process retrieves the original polarity from the deep interior, and the reversed field eventually vanishes. In the case of polarity reversal, on the other hand, the reversed polarity field is persistently generated deep within the core. It is then advected toward a shallow interior of the core, while the generation process of the reversed field occurs successively. The reversed polarity field near the core surface is collected by the downwelling flow associated with convection columns, as is the case for the original polarity field. The polarity reversal is completed by the advection process, the duration of which is consistent with the flow speed in the core.
| Original language | English |
|---|---|
| Pages (from-to) | 665-673 |
| Number of pages | 9 |
| Journal | earth, planets and space |
| Volume | 59 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - Jan 1 2007 |
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All Science Journal Classification (ASJC) codes
- Geology
- Space and Planetary Science
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A numerical study on magnetic polarity transition in an MHD dynamo model. / Takahashi, Futoshi; Matsushima, Masaki; Honkura, Yoshimori.
In: earth, planets and space, Vol. 59, No. 7, 01.01.2007, p. 665-673.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A numerical study on magnetic polarity transition in an MHD dynamo model
AU - Takahashi, Futoshi
AU - Matsushima, Masaki
AU - Honkura, Yoshimori
PY - 2007/1/1
Y1 - 2007/1/1
N2 - Magnetic polarity transitions in a Takahashi-Matsushima-Honkura dynamo model are analyzed. Distinctive differences in behavior of the axisymmetric poloidal magnetic field are found among a polarity reversal and excursions, including short polarity events. At the beginning of magnetic polarity transitions, the magnetic field with the reversed polarity is generated by anti-cyclonic convection columns deep within the outer core. In the case of excursion, it is soon advected by the radial flow toward a shallow interior of the core, and the transition can be detected at the core surface. However, the same process retrieves the original polarity from the deep interior, and the reversed field eventually vanishes. In the case of polarity reversal, on the other hand, the reversed polarity field is persistently generated deep within the core. It is then advected toward a shallow interior of the core, while the generation process of the reversed field occurs successively. The reversed polarity field near the core surface is collected by the downwelling flow associated with convection columns, as is the case for the original polarity field. The polarity reversal is completed by the advection process, the duration of which is consistent with the flow speed in the core.
AB - Magnetic polarity transitions in a Takahashi-Matsushima-Honkura dynamo model are analyzed. Distinctive differences in behavior of the axisymmetric poloidal magnetic field are found among a polarity reversal and excursions, including short polarity events. At the beginning of magnetic polarity transitions, the magnetic field with the reversed polarity is generated by anti-cyclonic convection columns deep within the outer core. In the case of excursion, it is soon advected by the radial flow toward a shallow interior of the core, and the transition can be detected at the core surface. However, the same process retrieves the original polarity from the deep interior, and the reversed field eventually vanishes. In the case of polarity reversal, on the other hand, the reversed polarity field is persistently generated deep within the core. It is then advected toward a shallow interior of the core, while the generation process of the reversed field occurs successively. The reversed polarity field near the core surface is collected by the downwelling flow associated with convection columns, as is the case for the original polarity field. The polarity reversal is completed by the advection process, the duration of which is consistent with the flow speed in the core.
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UR - http://www.scopus.com/inward/citedby.url?scp=34547981109&partnerID=8YFLogxK
U2 - 10.1186/BF03352729
DO - 10.1186/BF03352729
M3 - Article
AN - SCOPUS:34547981109
VL - 59
SP - 665
EP - 673
JO - Earth, Planets and Space
JF - Earth, Planets and Space
SN - 1343-8832
IS - 7
ER -