文章题目：The non‐negligible effect of viscosity diffusion on the geodynamo process
文章摘要：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 , we studied its impacts on weak and strong field geodynamo outputs by varying in two orders of magnitudes. In the weak field mode, the fluid velocity u varies with by a scaling law of 0.52u. While in the strong field mode, uvaries very slowly by a scaling law of 0.10u. The magnetic field B does not change much with when the driving force is not too strong (12,000aR) but decreases with by a scaling law of 0.20B when geodynamo operates in a very vigorous mode (50,000aR). The reason that u increases with is essential that increasing breaks the Taylor-Proudman constraint and drops the critical Rayleigh number, but this kind of increase of u does not give a stronger B. Furthermore, we conducted a local force balance analysis and demonstrated that the balance shifts under different . 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.
引用信息：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, e2020JB021281
