Thin shell dynamo models consistent with Mercury's weak observed magnetic field [rapid communication]
Thin shell dynamo models consistent with Mercury's weak observed magnetic field [rapid communication]
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与水星弱观测磁场一致的薄壳发电机模型[快速通讯]
DOI：
10.1016/j.epsl.2005.02.040
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发表时间：
2005
影响因子：
5.3
通讯作者：
M. Zuber
中科院分区：
文献类型：
--
作者：
S. Stanley;J. Bloxham;W. E. Hutchison;M. Zuber
能量平衡和磁转平衡论证表明，如果预期环向场和极向场的划分像地球一样，那么水星观测到的磁场的发电机来源是有问题的。我们进行了3维发电机数值模拟，以确定水星的薄壳发电机几何形状是否会产生非地球相似的磁场划分，从而为水星微弱的观测偶极信号提供可能的解释。我们考察了不同壳层厚度和瑞利数时核幔边界的偶极场与核环场的比值，发现一些薄壳发电机可以产生具有类汞偶极场强度的磁场。在这些发电机中，通过差动旋转产生的环向场比通过上升流与环向场相互作用产生的极向场更有效。与偶极场相比，极向场也由较小尺度的结构主导，这在水手10号任务中是看不到的。
Energetic and magnetostrophic balance arguments show that a dynamo source for Mercury's observed magnetic field is problematic if one expects an Earth-like partitioning of toroidal and poloidal fields. We perform 3-dimensional numerical dynamo simulations to determine if a thin shell dynamo geometry for Mercury could produce non-Earth-like magnetic field partitioning and therefore provide a possible explanation of Mercury's weak observed dipole signature. We examine the ratio of the dipole field at the core–mantle boundary to the toroidal field in the core for various shell thicknesses and Rayleigh numbers and find that some thin shell dynamos can produce magnetic fields with Mercury-like dipolar field intensities. In these dynamos, the toroidal field is produced more efficiently through differential rotation than the poloidal field is produced through upwellings interacting with the toroidal field. The poloidal field is also dominated by smaller-scale structure which was not observable by the Mariner 10 mission, compared to the dipole field.