Multidecadal variation of the Earth's inner-core rotation

被引:34
|
作者
Yang, Yi [1 ,2 ]
Song, Xiaodong [1 ,2 ]
机构
[1] Peking Univ, SinoProbe Lab, Beijing, Peoples R China
[2] Peking Univ, Inst Theoret & Appl Geophys, Sch Earth & Space Sci, Beijing, Peoples R China
基金
中国博士后科学基金; 国家重点研发计划; 中国国家自然科学基金;
关键词
TORSIONAL OSCILLATIONS; DIFFERENTIAL ROTATION; SCALE HETEROGENEITY; TEMPORAL-CHANGE; TOPOGRAPHY; ANISOTROPY; INVERSION; FIELD; BOUNDARY; VELOCITY;
D O I
10.1038/s41561-022-01112-z
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
Differential rotation of Earth's inner core relative to the mantle is thought to occur under the effects of the geodynamo on core dynamics and gravitational core-mantle coupling. This rotation has been inferred from temporal changes between repeated seismic waves that should traverse the same path through the inner core. Here we analyse repeated seismic waves from the early 1990s and show that all of the paths that previously showed significant temporal changes have exhibited little change over the past decade. This globally consistent pattern suggests that inner-core rotation has recently paused. We compared this recent pattern to the Alaskan seismic records of South Sandwich Islands doublets going back to 1964 and it seems to be associated with a gradual turning-back of the inner core as a part of an approximately seven-decade oscillation, with another turning point in the early 1970s. This multidecadal periodicity coincides with changes in several other geophysical observations, especially the length of day and magnetic field. These observations provide evidence for dynamic interactions between the Earth's layers, from the deepest interior to the surface, potentially due to gravitational coupling and the exchange of angular momentum from the core and mantle to the surface. Multidecadal oscillation of the Earth's inner core, coinciding with length of day and magnetic field variations, is experiencing a pause and reversing, according to analysis of repeating seismic waves traversing the inner core since the 1960s.
引用
收藏
页码:182 / +
页数:17
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