Modeling the Geomagnetic Field on Million Year Time Scales

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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.