Global characteristics of geomagnetic field reversals from data and numerical simulations

来自数据和数值模拟的地磁场反转的全球特征

• 批准号: 521251212
• 负责人: Dr. Monika Korte
• 金额: --
• 依托单位: Max-Planck-Institut für Sonnensystemforschung (MPS)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/521251212?language=en
• 关键词: Global; characteristics; geomagnetic; field; reversals

Understanding variabilities in the geomagnetic field reversal record is a central aspect in the priority programme DeepDyn, that aims at understanding Earth’s deep interior evolution throughout the geological history. However, to fully understand the reversal record and statistical properties of full reversals and short-lived excursions, which also sometimes include globally fully reversed field directions, a better understanding of the underlying processes of magnetic polarity changes is also necessary. Global models based on spherical harmonic basis functions offer the possibility to study global properties of the magnetic field during polarity transitions. The found characteristics can be directly compared to results from numerical simulations, which are based on considerations of the physical processes and force balances that drive the geodynamo. With the growing numbers of paleomagnetic records, both from sediment drill cores and lava sequences that are produced in paleomagnetic laboratories worldwide, global models have recently been developed for the Laschamps (41 000 years ago) and Norwegian-Greenland Basin (ca. 65 000 years ago) excursions, and a new model for the Matuyama-Brunhes reversal (ca. 780 000 years ago) is under construction. Here, we will develop the first global model of the Gauss-Matuyama reversal (ca. 2.6 million years ago). Together with the existing models this will enable us to study similarities and differences between at least four events, i.e. two full reversals and two excursions and provide a good understanding of robust statistical properties of some of the most recent magnetic field polarity changes. A growing number of numerical geodynamo simulations with different parameters and with or without boundary constraints, that e.g. mimic expected core-mantle boundary heat flux heterogeneities as inferred from seismic tomography models have reversals and excursions. We will perform a systematic study of different characteristics of polarity changes found in a large range of simulations. By comparisons between these and the results from the data based models we will gain a better understanding of the physical processes underlying the studied real events and the influence of the lower mantle on the geodynamo.

了解地磁领域逆转记录中的变异性是优先计划Deepdyn的核心方面，旨在了解地球整个地质历史上的深层室内发展。但是，为了充分了解完全逆转和短期偏移的逆转记录和统计特性，这有时还包括全球完全逆转的野外方向，对磁性极性变化的基本过程有了更好的理解。基于球形谐波基础功能的全局模型提供了研究极性转变期间磁场的全局特性的可能性。可以将发现的特征直接与数值模拟的结果进行比较，这些模拟基于对驱动Geodynamo的物理过程和力平衡的考虑。随着越来越多的古磁记录，包括在全球古磁实验室中产生的沉积物钻岩和熔岩序列，最近为拉桑普斯（41 000年前）开发了全球模型，以及挪威 - 格林兰德盆地和65 000年前的挪威 - 格林兰德盆地（Ca 65 000年前），在000年以前，是一个新的型号，是000年的新型号。 建造。在这里，我们将开发高斯 - 马图山逆转的首个全球模型（约260万年前）。与现有模型一起，这将使我们能够研究至少四个事件之间的相似性和差异，即两个完整的逆转和两次偏移，并对一些最新磁场极性变化的强大统计特性提供了很好的了解。越来越多的具有不同参数的数值Geodynamo模拟，并且具有或没有边界约束，例如从地震层析成像模型推断出的模拟预期核心边界热通量异质性具有逆转和偏移。我们将对在大量模拟中发现的极性变化的不同特征进行系统研究。通过比较这些与基于数据的模型的结果，我们将更好地理解研究二世真实事件的物理过程以及下壁架对Geodynamo的影响。