Modeling the Geomagnetic Field on Million Year Time Scales

研究人员将利用来自熔岩流和海洋沉积物的古地磁数据研究地磁场的长期变化。这些研究揭示了时均地磁场及其变异的结构，可能反映了核幔边界的热非均质性或成分地理非均质性。这些异质性可能最终控制地球动力学的性质，并为我们对地球深部过程的理解提供重要的见解。该项目的工作包括汇编和分析大型古地磁数据集，以及有助于分析的理论发展。研究人员将研究过去100万年时间平均场特征的持久性。此外，他们将扩展古长期变化的全球统计模型，包括在现有数据集中观察到的各向异性和一种模仿古地磁数据功率谱的时间协方差。他们将开发过去百万年间随时间变化的地磁场模型，并为数亿年至数百万年的古地磁强度变化构建一个功率谱。这些分析将允许研究可能导致地磁长期变化的物理过程，这些变化在几到100千万年的时间尺度上。所提议的工作涉及地磁场行为的各个方面，这些方面与地球深部过程（地核-地幔相互作用、内核演化和结构）密切相关，而且更有推测性地涉及轨道和旋转动力学对地球动力学的影响。由于研究人员建议将数据集、工具和产品系统地电子归档到社区数据库（MagIC）中，因此拟议的研究将对磁学社区产生长期影响。这些将对地/古磁学的其他研究人员有用，并且将被存档的产品（图像，模型，电影）将特别用于一般研究和教育目的。这里提出的研究将提供研究生教育，并构成两篇博士论文的核心，并为本科生提供研究经验。教育和推广工作将包括开发产品，以帮助支持通过SIO可视化中心运行的未来教师讲习班。调查人员还计划与高科技高中的科学教师合作，在那里他们正在开发一个突出当地研究的系列研讨会。

The investigators will study long term secular variations of the geomagnetic field using paleomagnetic data from lava flows and marine sediments. Such studies reveal can reveal structures in the time-averaged geomagnetic field and in its variability, which may reflect thermal or compositional geographical heterogeneities on the core-mantle boundary. These heterogeneities may ultimately control the nature of the geodynamo and provide important insight into our understanding of deep-earth processes. Work on this project involves compilation and analysis of large paleomagnetic datasets as well as theoretical developments that will aid in their analysis. The investigators will study the persistence of features in the time-averaged field for the past million years. In addition they will extend global statistical models for paleosecular variations to include anisotropy observed in existing datasets and temporal covariance of a kind that mimics that seen in the power spectrum of paleomagnetic data. They will develop time varying geomagnetic field models for the past million years, and construct a power spectrum for paleomagnetic intensity variations for time periods ranging from hundreds to millions of years. These analyses will allow studies of physical processes that might give rise geomagnetic secular variations on a few kyr to 100 kyr time scales.The work proposed deals with aspects of geomagnetic field behavior that are intimately linked to deep Earth processes (core-mantle interactions, inner core evolution and structure) and, more speculatively, to the influence of orbital and rotational dynamics on the geodynamo. The proposed research will have long-term impact for the magnetics community because the investigators propose systematic electronic archiving of data sets, tools, and products in a community database (MagIC). These will be of use to other researchers in geo/paleomagnetism, and the products that will be archived (images, models, movies) will be of particular use for general research and educational purposes. The research proposed here will provide graduate education and form the core of two PhD theses, as well as providing research experience to undergraduates. Education and outreach efforts will include the development of products to help support future teacher workshops run through the SIO visualization center. The investigators also plan to work in tandem with science teachers at High Tech High school where they are developing a seminar series highlighting local research.