A full-sphere convection-driven dynamo: Implications for the ancient geomagnetic field

作者：Zhan, Xiaoya^*; Zhang, Keke; Zhu, Rixiang

来源：Physics of the Earth and Planetary Interiors, 2011, 187(3-4): 328-335.

DOI：10.1016/j.pepi.2011.02.007

• Core convection
• Dynamo
• Inner core

The solid inner core of the Earth formed at 2-3 Ga as a result of the gradual cooling of the Earth's deep interior plays an essential role both energetically and dynamically, in the generation of the Earth's present magnetic field. In the early stage of the Earth's evolution, however, the entire core was made of molten liquid. Understanding convection-driven dynamo in a full sphere is hence of importance in elucidating the dynamics of the young Earth and its ancient magnetic field. We present a numerical convection and dynamo model for the full sphere using a finite element method. A large effort is made to efficiently parallelize the dynamo model so that it can take the full advantage of modern massively parallel computers. It is found that sustaining the full sphere dynamo - driven by convective flows in the absence of the tangent cylinder without imposing any boundary conditions at the center - is more difficult than that in spherical shells. Furthermore, the morphology of the magnetic field generated by the full sphere dynamo is largely dominated by non-dipolar components, indicating the structure of the ancient geomagnetic field prior to the onset of inner-core crystallization would be different from the current geomagnetic field.

• 出版日期2011-8
• 单位中国科学院地质与地球物理研究所兰州油气资源研究中心; 中国科学院地质与地球物理研究所