The Geomagnetic Field During the Holocene

全新世的地磁场全新世覆盖了过去10万年，这是人类知识和技术取得巨大发展的时期。在这段时间里，地磁场变化的记录被保存在考古文物、最近喷发的熔岩流和分布在世界各地的快速沉积的沉积物中。考古地磁和古地磁记录的汇编，其日期通常可以被高精度地确定，正被用来制作可追溯到10~ka的连续时变地磁场模型。这些正则化模型被称为CALS10K，分别用球面谐波和三次b样条曲线表示场的时空变化。该提案的工作是通过更新数据汇编来改进现有的模型，并开发新的反演技术来整合来自沉积物的相对地磁古强度变化记录。为了研究地磁偶极矩的精细尺度变化，目前正在开发具有尽可能高的时间分辨率的模式。由此产生的CALS10K模型将用于解决一系列突出的地磁问题：从长期来看，偶极子的主导地位如何？南大西洋磁异常存在多久了？它是如何随着时间发展的？太平洋半球的磁场及其长期变化是否一直低于大西洋半球？是否有观测证据表明地磁场中存在波动？在什么时间尺度上？它的物理起源是什么？正在开发的数据集、工具和产品将被归档到MagIC社区数据库中。

The Geomagnetic Field during the Holocene The Holocene covers the past 10 kyr, a period in which there has been tremendous growth in human knowledge and technology. Throughout this time records of the changing geomagnetic field have been preserved in archeological artifacts, recently erupted lava flows, and rapidly deposited sediments distributed around the world. Compilations of archeomagnetic and paleomagnetic records, whose dates can often be identified to high accuracy, are being used to make continuous time-varying geomagnetic field models that extend back to 10~ka. These regularized models, known as CALS10K, represent the spatial and temporal variations of the field with spherical harmonics and cubic B-splines respectively. Work under this proposal is improving existing models by updating data compilations, and developing new inversion techniques to incorporate records of relative geomagnetic paleointensity variations derived from sediments. Models with the highest possible temporal resolution are under development in order to study fine scale variations in geomagnetic dipole moment.The resulting CALS10K models are going to be used to address a series of outstanding geomagnetic questions:How dominant is the dipole over the longer term? How long has the S. Atlantic magnetic anomaly existed? How has it evolved with time? Is the magnetic field and its secular variation persistently lower in the Pacific than in the Atlantic hemisphere?Is there observational evidence for wave motion in the geomagnetic field? On what time scales? What might be its physical origin?Data sets, tools, and products that are being developed will be archived in the MagIC community database.