近日，南方科技大学林玉峰团队揭示了早期地球模型中发电机作用的不变性。相关论文发表在2025年7月30日出版的《自然》杂志上。

地球上的磁场产生可能至少持续了3.5 Gyr，最初是由地核的长期冷却维持的，近期是由固体内核的生长维持的。目前地球发电机作用的数值模型已被证明能成功地产生类似地球的磁场，并能接近现实的动态状态。然而，热演化和古地磁记录表明，在没有固体内核的地磁历史的大部分时间里，地球发电机都在运行。发电机在整个流体堆芯中的作用仍然知之甚少。

研究组展示了在遥远的过去，在极低的粘度下，在地球核心的正确几何形状中，发电机的作用与流体粘度无关，证明了流体粘度在发电机模型中的作用可以忽略不计。研究组的早期地球几何模型产生的磁场强度和形态与远古时期的古地磁数据相一致，同时与现今的磁场表现出显著的相似性。这引发了关于固态内核在产生观测到的地球磁场时空变化中的作用的问题。

附：英文原文

Title: Invariance of dynamo action in an early-Earth model

Author: Lin, Yufeng, Marti, Philippe, Jackson, Andrew

Issue&Volume: 2025-07-30

Abstract: Magnetic field generation on Earth has probably persisted for at least 3.5Gyr (refs.1,2), initially sustained by secular cooling of the Earth’s core and, more recently, by the growth of the solid inner core3. Numerical models of the present-day geodynamo have proved to be successful in producing Earth-like magnetic fields4,5,6,7 and approaching realistic dynamic regimes8,9,10,11. However, thermal evolution12,13 and palaeomagnetic records14,15 suggest that the geodynamo operated for most of geomagnetic history without a solid inner core. Dynamo action in a whole fluid core remains poorly understood. Here we show dynamo actions that are independent of fluid viscosity in the correct geometry of the Earth’s core in the deep past at extremely low viscosity, demonstrating the negligible role of fluid viscosity in our dynamo simulations. Our early-Earth geometry models produce magnetic field intensity and morphologies that are compatible with the palaeomagnetic data in the deep past while showing remarkable similarity to the present-day magnetic field. This raises questions about the role of the solid inner core in producing the spatial-temporal variations of the observed Earth’s magnetic field7,16,17,18.

DOI: 10.1038/s41586-025-09334-y

Source: https://www.nature.com/articles/s41586-025-09334-y