Collaborative Research: Long Term Structure and Variability in the Geomagnetic Field: The View from Lavas, Sediments and Magnetic Anomalies

9526682约翰逊 熔岩流、海洋沉积物和磁异常数据将用于模拟地磁场的长期结构和变化。 从熔岩流和沉积物的数据表明不同的平均场配置在正常和反极性期间，在过去的5Ma，虽然个人模型的基础上，每种类型的数据约束不足。 PI建议调查需要多长时间间隔来对长期变化的整个范围进行采样，以获得地磁场的良好平均值。 PI还将使用古强度数据导出新的古长期变化模型。 现有的古强度数据与康斯特布尔帕克的当前模型不兼容，该模型相对于任何地心坐标系都是同位素变化。 我们将利用进化规划来寻找新的模型，这些模型考虑到了沿地理轴沿着的各向异性。 将通过寻找与历史磁场中所见类似结构相对应的时均磁场和古长期变化中的异常来研究地磁场中可能反映核幔边界条件控制的非常长期（数百万年）的非纬向结构。

9526682 Johnson Lava flows, marine sediments and magnetic anomaly data will be used to model the long term structure and variability in the geomagnetic field. Data from both lava flows and sediments indicated different average field configurations during normal and reverse polarity periods for the past 5Ma, although the individual models based on each type of data are poorly constrained. The PI's propose to investigate how long a time interval is required to sample the full range of secular variation to get a good average of the geomagnetic field. The PI's will also use paleointensity data to derive new paleosecular variation models. Existing paleointensity data are incompatible with the current model of Constable & Parker, that is isotopic in variability with respect to any geocentric coordinate system. New models will sought, using evolutionary programming, that allow for anisotropy along the geographic axis. Very long-term (millions of years) non-zonal structure in the geomagnetic field, that may reflect control by core-mantle boundary conditions will be investigated by looking for anomalies in the time-averaged field and the paleosecular variation that correspond to similar structures seen in the historical field.