Studies of geomagnetic variations using 3D mean-field dynamo models based on spectral filtering

使用基于光谱滤波的 3D 平均场发电机模型研究地磁变化

• 批准号: 5249428
• 负责人: Professor Dr. Norbert Seehafer
• 金额: --
• 依托单位: Leibniz-Institut für Astrophysik Potsdam (AIP)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2000
• 资助国家: 德国
• 起止时间: 1999-12-31 至 2002-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5249428?language=en
• 关键词: Studies; geomagnetic; variations; using; 3D

The variations of the geomagnetic main field such as drifts, excursions or reversals reflect the complex nature of the motions in the Earth's core. The observed features of these variations should be understood on the basis of sufficiently detailed simulations of the dynamo process in the Earth's core, which consists in very complex interactions of the magnetic field with fluid motions caused by thermal or other instabilities. Despite very impressive progress in this respect, simulations of these processes with material parameters really close to those of the Earth's core are still missing. Our project aims to study the time behavior of the geodynamo on the simpler level of mean-field dynamo models. However, a new mean-field concept is used, with mean fields defined by filtering of the multipole spectra of the original fields. It avoids shortcomings of the traditional concept, which made its application to the Earth's core rather problematic. In our models patterns of the convective motions are used originating from simulations under conditions which are realistic for the situation to be assumed in the Earth's core. The main result we expect from the proposed work is a contribution to understanding the time variations of the geomagnetic field and their connection with the fluid motions in the Earth's core.

地磁主场的变化，如漂移、偏移或反转，反映了地核运动的复杂性质。观察到的这些变化的特征应该基于对地核发电机过程的足够详细的模拟来理解，该发电机过程包括磁场与由热或其他不稳定性引起的流体运动的非常复杂的相互作用。尽管在这方面取得了非常令人印象深刻的进展，但仍然缺少对这些过程的材料参数非常接近地核参数的模拟。我们的项目旨在研究地球发电机在更简单的平均场发电机模型水平上的时间行为。然而，使用了新的平均场概念，通过对原始场的多极谱进行滤波来定义平均场。它避免了传统概念的缺点，而传统概念的缺点使其在地核应用中存在相当大的问题。在我们的模型中，对流运动的模式是根据在地球核心假设的情况的真实条件下进行的模拟而使用的。我们期望这项工作的主要结果是有助于理解地磁场的时间变化及其与地核流体运动的联系。