论文标题

双极磁区和太阳的Babcock-Leighton dynamo的三维非依次模拟

Three-dimensional non-kinematic simulation of post-emergence evolution of bipolar magnetic regions and Babcock-Leighton dynamo of the Sun

论文作者

Bekki, Yuto, Cameron, Robert H.

论文摘要

Babcock-Leighton(BL)通量传输模型是一个广泛认可的太阳的发电机模型。该发电机模型已在运动学和非依次制度中的二维(2D)平均场框架中进行了广泛的研究。最近的三维(3D)模型仅限于运动学制度。在这些模型中,表面螺栓通量是由根据Joy定律倾斜的双极磁区域(BMR)的出现产生的。我们研究了3D非基因模拟中BMR出现的处方。我们还报告了循环BL Dynamo模拟的初始结果。我们将BL通量 - 传输发电机的常规2D平均场模型扩展到3D非依次制度。大规模平均流是由该模型中的参数化$λ$效应驱动的。对于诱导方程,我们使用BL源项,通过该项响应于对流区域内的动力学的环形场而产生表面BMR。我们发现,在3D非依基制度中,新出现的BMR的倾斜角对BMR的地下结构的处方非常敏感。除非将BMR深深嵌入对流区域,否则会发现反joy倾斜角。我们还发现,领先地点往往比以下位置更强大。 BMR的反乔伊定律趋势和形态不对称可以通过作用于洛伦兹 - 强度驱动的流动的科里奥利力来解释。此外,我们证明,如果在BL $α$效应中明确给出Joy的定律,则可以成功获得太阳能磁性循环。在这些环状发电机模拟中,强的洛伦兹力反馈会导致差异旋转和子午循环中的循环调制。发现流的非轴对称成分是作为惯性模式(例如赤道罗斯比模式)存在的。

The Babcock-Leighton (BL) flux-transport model is a widely-accepted dynamo model of the Sun. This dynamo model has been extensively studied in a two-dimensional (2D) mean-field framework in both kinematic and non-kinematic regimes. Recent three-dimensional (3D) models have been restricted to the kinematic regime. In these models, the surface poloidal flux is produced by the emergence of bipolar magnetic regions (BMRs) that are tilted according to Joy's law. We investigate the prescription for emergence of a BMR in 3D non-kinematic simulations. We also report initial results of cyclic BL dynamo simulation. We extend a conventional 2D mean-field model of the BL flux-transport dynamo into 3D non-kinematic regime. The large-scale mean flows are driven by the parameterized $Λ$-effect in this model. For the induction equation, we use a BL source term by which the surface BMRs are produced in response to the dynamo-generated toroidal field inside the convection zone. We find that, in the 3D non-kinematic regime, the tilt angle of a newly-emerged BMR is very sensitive to the prescription for the subsurface structure of the BMR. Anti-Joy tilt angles are found unless the BMR is deeply embedded in the convection zone. We also find that the leading spot tends to become stronger than the following spot. The anti-Joy's law trend and the morphological asymmetry of the BMRs can be explained by the Coriolis force acting on the Lorentz-force-driven flows. Furthermore, we demonstrate that the solar-like magnetic cycles can be successfully obtained if the Joy's law is explicitly given in the BL $α$-effect. In these cyclic dynamo simulation, a strong Lorentz force feedback leads to cycle modulations in the differential rotation and meridional circulation. The non-axisymmetric components of the flows are found to exist as inertial modes such as the equatorial Rossby modes.

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