地球固体内核的结晶生长释放出潜热和轻元素，在导电的液态外核中驱动对流运动并通过磁流体发电机产生现今的地球主磁场。地球的热演化历史表明地球的固体内核约形成于5-20亿年前，但古地磁记录表明地球主磁场已经存在了至少34.5亿年，这说明在相当长的地球历史时期内地球发电机是在没有固体内核的情形下维持运行的。目前对于地球发电机的研究主要是基于现今的地球内部结构的，然而固体内核形成之前地球发电机的驱动机制以及产生磁场形态与现今的情形可能不尽相同。本项目拟通过数值模拟来分析固体内核形成之前古发电机的能量来源、驱动机制及其产生的古地磁场的时空变化特征。对于地球内核形成之前古发电机的研究，结合古地磁记录以及对比现今的地球发电机模型，将为地核的演化历史、地球内核的年龄等关键的科学问题提供重要约束。

Earth's internal magnetic field is generated in the liquid outer core through the dynamo action. The present-day geodynamo is mainly powered by convection due to the solidification of the inner core, which releases latent heat and light elements. Studies of the thermal history of the Earth suggest that the inner core formed about 0.5-2 billion years ago, but paleomagnetic records indicate that the Earth's magnetic field has existed for at least 3.45 billion years, meaning that the geodynamo had been operating without the solid inner core for a long time span. Previous studies on geodynamo have mainly focused on the present-day model. However, the ancient dynamo before the inner core formation can be quite different from the present one. This project aims to investigate the geodynamo before the inner core formation via numerical simulations. We will especially investigate the energy sources, driving mechanisms of the ancient dynamo and spatial-temporal variations of the magnetic field before the inner core formation. Combining the paleomagnetic records and the present-day geodynamo model, this study will provide significant constraints on the evolution of the Earth’s core and the age of the solid inner core.