DOI: 10.1016/j.epsl.2017.11.007
Scopus记录号: 2-s2.0-85034606283
论文题名: Mechanism of the interannual oscillation in length of day and its constraint on the electromagnetic coupling at the core–mantle boundary
作者: Duan P. ; Liu G. ; Hu X. ; Zhao J. ; Huang C.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 482 起始页码: 245
结束页码: 252
语种: 英语
英文关键词: core–mantle boundary
; damping model
; electromagnetic coupling
; Interannual variation
; length of day
Scopus关键词: Electromagnetic coupling
; Estimation
; Damping model
; Electromagnetic (em) coupling
; Inner core boundary
; Interannual variation
; Length of days
; Mathematical expressions
; Quality factor Q
; Radial magnetic field
; Oscillating cylinders
; annual variation
; core-mantle boundary
; coupling
; damping
; electromagnetic field
; oscillation
英文摘要: A significant 6 yr oscillation exists in the length of day (LOD) on the interannual scales. There are mainly two models currently to explain this oscillation, i.e., mantle–inner core gravitational (MICG) coupling mode and the fast torsional waves within the fluid outer core. The former has been doubted, while the source of the excitation of the latter is not yet understood. Therefore, the mechanism of the 6 yr oscillation is still not clear. Here, by considering the mantle and inner core angular momentum, we investigate the MICG coupling mode and its natural period (T0). Given that the strength of gravitational core–mantle coupling (Γ¯) within a recently constrained range is quite weaker than that estimated previously, the mechanism of the 6 yr oscillation still can be attributed to MICG coupling mode (i.e., T0 equals to 6 yrs), but, we require the inertia moment of fluid within the tangent cylinder involved in the 6 yr oscillation to be smaller than 1.23×1035 kgm2. This interpretation can be used to constrain the electromagnetic (EM) coupling at the inner core boundary (ICB). In order to study quantitatively the constraints on the EM coupling at the core–mantle boundary (CMB) from the observed 6 yr oscillation with a quality factor Q (∼51.6), we further develop the mathematical expression between the Q value based on the observations and EM coupling at the CMB. According to the Γ¯ value from recent estimates and assuming that the 6 yr oscillation is in a free decay, we can obtain the radial magnetic field at the CMB is 0.52 mT∼0.62 mT when conductance at the CMB is 108 S. © 2017 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110133
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Institute of Geodesy and Geophysics, Chinese Academy of Sciences, State Key Laboratory of Geodesy and Earth's Dynamics, Wuhan, 430077, China; CAS Key Laboratory of Planetary Sciences, Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai, 200030, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Institute of Surveying and Mapping, China Railway Er yuan Engineering Group CO.LTD, Chengdu, 610000, China
Recommended Citation:
Duan P.,Liu G.,Hu X.,et al. Mechanism of the interannual oscillation in length of day and its constraint on the electromagnetic coupling at the core–mantle boundary[J]. Earth and Planetary Science Letters,2018-01-01,482