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

9526682约翰逊熔岩流动、海洋沉积物和磁异常数据将被用来模拟地磁场的长期结构和变异性。来自熔岩流和沉积物的数据表明，在过去5 Ma期间，正极性和反极性期间的平均场配置不同，尽管基于每种类型数据的单独模型约束较差。PI建议调查需要多长时间间隔才能对长期变化的全部范围进行采样，以获得良好的地磁场平均值。PI还将利用古强度数据来推导新的古分子变化模型。现有的古强度数据与康斯特布尔和帕克目前的模型不相容，该模型关于任何地心坐标系的可变性是同位素的。将利用进化编程寻找新的模型，允许沿地理轴的各向异性。将通过寻找时间平均场中的异常和对应于历史场中类似结构的古分子变化来研究地磁场中可能反映核-地幔边界条件控制的极长期(数百万年)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.