气候变化领域集成服务门户(CCPortal): The Non-Negligible Effect of Viscosity Diffusion on the Geodynamo Process

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DOI	10.1029/2020JB021281
	The Non-Negligible Effect of Viscosity Diffusion on the Geodynamo Process
	Dong C.; Zhang H.; Jiao L.; Cheng H.; Yuen D.A.; Shi Y.
发表日期	2021
ISSN	21699313
卷号	126 期号:6
英文摘要	Exploring geodynamo's scaling laws is of great importance when a tremendous gap still lies between realistic physics and estimated model parameters. Existing scaling laws need to be tested by numerical simulations. To boost these, taking the outer core viscosity (Formula presented.), we studied its impacts on weak and strong field geodynamo outputs by varying (Formula presented.) in two orders of magnitudes. In the weak field mode, the fluid velocity (Formula presented.) varies with (Formula presented.) by a scaling law of (Formula presented.). While in the strong field mode, (Formula presented.) varies very slowly by a scaling law of (Formula presented.). The magnetic field (Formula presented.) does not change much with (Formula presented.) when the driving force is not too strong ((Formula presented.)) but decreases with (Formula presented.) by a scaling law of (Formula presented.) when geodynamo operates in a very vigorous mode ((Formula presented.)). The reason that (Formula presented.) increases with (Formula presented.) is essential that increasing (Formula presented.) breaks the Taylor-Proudman constraint and drops the critical Rayleigh number, but this kind of increase of (Formula presented.) does not give a stronger (Formula presented.). Furthermore, we conducted a local force balance analysis and demonstrated that the balance shifts under different (Formula presented.). In a quasi-MAC regime, the Lorentz force instead of the inertial force enters into the first-order agostrophic force balance, though the viscous force still plays a role. Comparing with other scaling laws previous wisdom holds, we propose that the effect of viscosity diffusion is non-negligible for both existing weak and strong dynamo regimes. Still, appropriate assumptions can be made to take this variation into account. © 2021. The Authors.
英文关键词	force balance; geodynamo; outer core; thermal convection; viscosity
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/187089
作者单位	Institute of Geophysics, Chinese Earthquake Administration, Beijing, China; Key Laboratory of Computational Geodynamics, University of Chinese Academy of Sciences, Beijing, China; Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China; Department of Earth Sciences, University of Minnesota, Minneapolis, MN, United States
推荐引用方式 GB/T 7714	Dong C.,Zhang H.,Jiao L.,et al. The Non-Negligible Effect of Viscosity Diffusion on the Geodynamo Process[J],2021,126(6).
APA	Dong C.,Zhang H.,Jiao L.,Cheng H.,Yuen D.A.,&Shi Y..(2021).The Non-Negligible Effect of Viscosity Diffusion on the Geodynamo Process.Journal of Geophysical Research: Solid Earth,126(6).
MLA	Dong C.,et al."The Non-Negligible Effect of Viscosity Diffusion on the Geodynamo Process".Journal of Geophysical Research: Solid Earth 126.6(2021).