A numerical study on magnetic polarity transition in an MHD dynamo model

Futoshi Takahashi, Masaki Matsushima, Yoshimori Honkura

Research output: Contribution to journalArticle

18 Citations (Scopus)

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 languageEnglish
Pages (from-to)665-673
Number of pages9
Journalearth, planets and space
Volume59
Issue number7
DOIs
Publication statusPublished - Jan 1 2007

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magnetic reversal
polarity
convection
magnetic field
outer core
radial flow
downwelling
advection
magnetic fields
near fields

All Science Journal Classification (ASJC) codes

  • Geology
  • Space and Planetary Science

Cite this

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 journalArticle

Takahashi, Futoshi ; Matsushima, Masaki ; Honkura, Yoshimori. / A numerical study on magnetic polarity transition in an MHD dynamo model. In: earth, planets and space. 2007 ; Vol. 59, No. 7. pp. 665-673.
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