Numerische Simulationen des Geodynamos mit thermo-chemischem Antrieb

地球液核中的流体运动驱动发电机被认为是其内部磁场的主要来源。液态外核被认为是由主要是铁和镍以及少量较轻元素（如硫、氧或硅）的混合物组成。有两个潜在的来源可用于驱动对流，从而驱动液态外核中的发电机：由于温度和成分差异引起的浮力引起的密度变化。温差是地球长期变冷的结果。一旦行星冷却到足以形成固体内核，在凝固过程中释放的潜热就为热对流提供了另一个来源。另外的成分差异是由于轻元素从内核边界处的固化材料中释放出来。到目前为止，地球发电机模拟没有考虑到可能出现的影响，从存在两个浮力源具有显着不同的扩散时间尺度。因此，本建议的目的是通过数值模型研究旋转球壳中的热化学驱动发电机。通过考虑不同的热与化学强迫比，我们希望更好地了解地核内磁场的产生以及地球发电机的时空行为。

Fluid motions in the Earth’s liquid core driving a dynamo are thought to be the main source for its internal magnetic field. The liquid outer core is assumed to be composed of a mixture of predominantly iron and nickel and a small fraction of lighter elements (e.g. sulphur, oxygen or silicon). Two potential sources are available for driving convection and thereby the dynamo in the liquid outer core: density variations due to temperature and due to compositional differences inducing buoyancy. Temperature differences result from secular cooling of the planet. Once the planet has cooled enough to grow a solid inner core the latent heat being released in the solidification process provides another source for thermal convection. The additional compositional differences arise from light elements being released from the solidifying material at the inner core boundary. So far, Geodynamo simulations do not take into account the effects that may arise from the presence of two buoyancy sources with significantly different diffusion time scales. For this reason the aim of this proposal is to study thermo-chemically driven dynamos in rotating spherical shells by means of a numerical model. By considering different thermal to chemical forcing ratios we hope to get a better general understanding of magnetic field generation within the Earth’s core and the spatio-temporal behavior of the Geodynamo.