气候变化领域集成服务门户(CCPortal): Response of Earth's magnetic field to large lower mantle heterogeneity

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DOI	10.1016/j.epsl.2020.116507
	Response of Earth's magnetic field to large lower mantle heterogeneity
	Sahoo S.; Sreenivasan B.
发表日期	2020
ISSN	0012821X
卷号	549
英文摘要	A simplified two-fold pattern of convection in the Earth's core is often used to explain the non-axisymmetric magnetic flux concentrations in the present day geomagnetic field. For large lateral variations in the lower mantle heat flux, however, a substantial east–west dichotomy in core convection may be expected. This study examines the effect of a large lateral variation in heat flux at the outer boundary in cylindrical annulus experiments that achieve approximate geostrophy of the convection as well as in rapidly rotating spherical shell simulations. In either geometry, the imposed boundary heat flux is derived from the seismic shear wave velocity in the lowermost mantle. The pattern of large-scale convection in the simulations closely follows that in the annulus experiments, which suggests that the lateral buoyancy at the equator essentially determines the structure of core convection. In particular, the location of a coherent downwelling that forms beneath Canada in mildly driven convection entirely switches over to the Siberian region in strongly driven states. Spherical dynamo models in turn show that this eastward migration of convection causes the relative instability or even the disappearance of the high-latitude magnetic flux in the Western hemisphere. Finally, large radial buoyancy causes homogenization of convection, which may place an upper bound for the Rayleigh number in the core. © 2020 Elsevier B.V.
关键词	core flows core–mantle interaction geomagnetic field
英文关键词	Buoyancy; Geomagnetism; Heat convection; Magnetic flux; Shear flow; Shear waves; Wave propagation; Boundary heat flux; Cylindrical annulus; Earth's magnetic field; Geomagnetic fields; Lateral variations; Magnetic flux concentration; Relative instability; Shear wave velocity; Heat flux; core (planetary); experiment; geomagnetic field; geostrophic flow; heat flux; heterogeneity; lower mantle; mantle convection; spatial variation; Canada
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/202872
作者单位	Department of Applied Geophysics, Indian Institute of Technology (ISM), Dhanbad, 826004, India; Centre for Earth Sciences, Indian Institute of Science, Bangalore, 560012, India
推荐引用方式 GB/T 7714	Sahoo S.,Sreenivasan B.. Response of Earth's magnetic field to large lower mantle heterogeneity[J],2020,549.
APA	Sahoo S.,&Sreenivasan B..(2020).Response of Earth's magnetic field to large lower mantle heterogeneity.Earth and Planetary Science Letters,549.
MLA	Sahoo S.,et al."Response of Earth's magnetic field to large lower mantle heterogeneity".Earth and Planetary Science Letters 549(2020).