Fluid motion of the outer core in response to a temperature heterogeneity at the core-mantle boundary and its dynamo action.

Shigeo Yoshida, Yozo Hamano

研究成果: Contribution to journalArticle査読

5 被引用数 (Scopus)

抄録

We perform a simple linear analysis of the response of the outer core fluid to a sectorial temperature heterogeneity at the core-mantle boundary (CMB). The locations of upwellings and downwellings are shown to be controlled by the Elsasser number. When the Elsasser number is less than the order of unity, upwellings occur to the east of hot regions, and downwellings occur to the west of hot regions. When the Elsasser number is more than the order of unity, upwellings occur beneath hot regions, and downwellings occur beneath cold regions. Our theory provides an explanation for the correlation between the observed magnetic feature and the lateral heterogeneity of the seismic velocity in the lower mantle, which would correspond to the temperature heterogeneity at the CMB. From the correlation, we infer that the Elsasser number is a little less than unity in the Earth's outer core. Moreover, we investigate whether the resulting flow can sustain dynamo action or not. A temperature heterogeneity of the order of 10-6 K over a length scale of 103 km would be sufficient for the generation of dynamo action.

本文言語英語
ページ(範囲)1497-1516
ページ数20
ジャーナルJournal of geomagnetism and geoelectricity
45
DOI
出版ステータス出版済み - 1993
外部発表はい

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)
  • Earth and Planetary Sciences(all)

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