气候变化领域集成服务门户(CCPortal): Inner Core and Its Libration Under Gravitational Equilibrium: Implications to Lower-Mantle Density Anomaly

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DOI	10.1029/2020JB020541
	Inner Core and Its Libration Under Gravitational Equilibrium: Implications to Lower-Mantle Density Anomaly
	Shih S.A.; Chao B.F.
发表日期	2021
ISSN	21699313
卷号	126 期号:1
英文摘要	The inner core's (IC) axial torsional libration (ATL) is a manifestation of the mantle-inner core gravitational rotational normal mode. Its natural period is critically determined by the interior sectoral quadrupole (Formula presented.) (of mass distribution of spherical-harmonic degree 2 and order 2) belonging to the mantle plus the core-mantle boundary. We derive the (multipole) formalism to calculate (Formula presented.) based on two physical postulations: (i) Postulation I that equates the observed 6-year variation in Earth's length-of-day to ATL as laid out in Chao (2017, https://doi.org/10.1002/2016JB013515); (ii) Postulation II requiring that the shape of IC, thanks to its finite viscosity, conforms to the gravitational equipotential surface in the long term. (Formula presented.) being a complex value, its phase relation with ATL asserts that the major axis of the IC aligns with that of (Formula presented.) subject to the lowest-energy state. The magnitude of (Formula presented.) thus evaluated by Earth parameters is (Formula presented.) (the two endmember values corresponding respectively to IC's nominal polar moment of inertia vs. the effective value under 100% tangent-cylinder coupling). The corresponding equatorial elliptical shape of the IC under Postulation II has peak-to-peak topography of 75–164 m. The acquired (Formula presented.) can serve as source information for inversion on, among others, the density anomaly of the large low shear velocity provinces constructs in the lower mantle. © 2020. American Geophysical Union. All Rights Reserved.
英文关键词	core-mantle boundary; density anomaly; inner core; libration; lower mantle
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187413
作者单位	Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
推荐引用方式 GB/T 7714	Shih S.A.,Chao B.F.. Inner Core and Its Libration Under Gravitational Equilibrium: Implications to Lower-Mantle Density Anomaly[J],2021,126(1).
APA	Shih S.A.,&Chao B.F..(2021).Inner Core and Its Libration Under Gravitational Equilibrium: Implications to Lower-Mantle Density Anomaly.Journal of Geophysical Research: Solid Earth,126(1).
MLA	Shih S.A.,et al."Inner Core and Its Libration Under Gravitational Equilibrium: Implications to Lower-Mantle Density Anomaly".Journal of Geophysical Research: Solid Earth 126.1(2021).