气候变化领域集成服务门户(CCPortal): Ohmic dissipation in the Earth's outer core resulting from the free inner core nutation

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DOI	10.1016/j.epsl.2019.115888
	Ohmic dissipation in the Earth's outer core resulting from the free inner core nutation
	Lin Y.; Ogilvie G.I.
发表日期	2020
ISSN	0012821X
卷号	530
英文摘要	The diurnal tidal forces can excite a normal mode of the Earth's core, the free inner core nutation (FICN), which is characterized by a tilt of the rotation axis of the inner core with respect to the rotation axis of the outer core. The differential rotation between the inner core and the outer core induces fluid motions in the outer core and gives rise to Ohmic dissipation in the presence of the Earth's internal magnetic field. Nutation measurements can reflect such dissipation if it is sufficiently strong and thus can provide insights into the properties and dynamics of the Earth's core. In this study we perform a set of numerical calculations of the linear perturbations in the outer core induced by the FICN at very low Ekman numbers (as small as 10−11). Our numerical results show that the back-reaction of the magnetic field notably alters the structure and length scale of the perturbations induced by the FICN, and thus influences the Ohmic dissipation resulting from the perturbations. When the Ekman number is sufficiently small, Ohmic dissipation tends to be insensitive to the fluid viscosity and to the magnetic diffusivity, which allows us to estimate the Ohmic dissipation associated with the FICN without relying on an extrapolation. In contrast to the results of Buffett (2010b), the estimated Ohmic dissipation based on our numerical calculations is too weak to account for the observed damping of the FICN mode. This also implies that nutation measurements cannot provide effective constraints on the strength of the magnetic field inside the Earth's outer core. © 2019 Elsevier B.V.
关键词	Earth's core Earth's magnetic field inertial waves nutation Ohmic dissipation
英文关键词	Geology; Mathematical models; Earth's core; Earth's magnetic field; Inertial waves; nutation; Ohmic dissipation; Magnetic fields; Ekman layer; energy dissipation; geomagnetic field; inner core; nutation; outer core; perturbation
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202743
作者单位	Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen, 518055, China; Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, United Kingdom
推荐引用方式 GB/T 7714	Lin Y.,Ogilvie G.I.. Ohmic dissipation in the Earth's outer core resulting from the free inner core nutation[J],2020,530.
APA	Lin Y.,&Ogilvie G.I..(2020).Ohmic dissipation in the Earth's outer core resulting from the free inner core nutation.Earth and Planetary Science Letters,530.
MLA	Lin Y.,et al."Ohmic dissipation in the Earth's outer core resulting from the free inner core nutation".Earth and Planetary Science Letters 530(2020).