DOI: 10.1002/2016GL068301
论文题名: Electrical conductivity of the lowermost mantle explains absorption of core torsional waves at the equator
作者: Schaeffer N. ; Jault D.
刊名: Geophysical Research Letters
ISSN: 0094-9663
EISSN: 1944-9394
出版年: 2016
卷: 43, 期: 10 起始页码: 4922
结束页码: 4928
语种: 英语
英文关键词: core-mantle coupling
; mantle conductivity
; torsional waves
Scopus关键词: Elastic waves
; Geomagnetism
; Conducting layers
; Core-mantle
; Electrical conductivity
; Geomagnetic model
; Inversion techniques
; Momentum exchange
; Ohmic dissipation
; Radial magnetic field
; Angular momentum
英文摘要: Torsional Alfvén waves propagating in the Earth's core have been inferred by inversion techniques applied to geomagnetic models. They appear to propagate across the core but vanish at the equator, exchanging angular momentum between core and mantle. Assuming axial symmetry, we find that an electrically conducting layer at the bottom of the mantle can lead to total absorption of torsional waves that reach the equator. We show that the reflection coefficient depends on G(Formula presented.)r, where (Formula presented.)r is the strength of the radial magnetic field at the equator, and G the conductance of the lower mantle there. With (Formula presented.)r=7 × 10-4 T, torsional waves are completely absorbed when they hit the equator if G≃1.3 × 108 S. For larger or smaller G, reflection occurs. As G is increased above this critical value, there is less attenuation and more angular momentum exchange. Our finding dissociates efficient core-mantle coupling from strong ohmic dissipation in the mantle. ©2016. American Geophysical Union. All Rights Reserved. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971221604&doi=10.1002%2f2016GL068301&partnerID=40&md5=4b50c1ec7bcd5a78a0dd456c7b1d1cf8
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/10626
Appears in Collections: 科学计划与规划 气候变化与战略
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作者单位: CNRS, ISTerre, University of Grenoble Alpes, Grenoble, France
Recommended Citation:
Schaeffer N.,Jault D.. Electrical conductivity of the lowermost mantle explains absorption of core torsional waves at the equator[J]. Geophysical Research Letters,2016-01-01,43(10).