On electromagnetic core-mantle coupling
作者:
M. Stix,
期刊:
Geophysical & Astrophysical Fluid Dynamics
(Taylor Available online 1982)
卷期:
Volume 21,
issue 3-4
页码: 303-313
ISSN:0309-1929
年代: 1982
DOI:10.1080/03091928208209018
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
The induced magnetic field in the Earth's mantle is computed for an electrical conductivity of the mantle of form σ = σa(a/r)αwhereais the core radius. When the inducing core motion is a uniform westward drift of −10−10s−1relative to the mantle, the retarding couple reaches −1019Nm. This result can be obtained with values σαand α such that the time scale of screening, μσa2/α2, is still below 10 years. The retarding couple, and in particular the contribution from the higher field harmonics, increases with increasing concentration of the conducting layer towards the core-mantle boundary. Deviations from the average torque balance of order 10% of the retarding couple can account for the “decade fluctuations” in the Earth's rate of rotation.
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