EAR-PF: Mesozoic Geomagnetic Field Behavior: Exploring Mesozoic core dynamics by tuning numerical geodynamo simulations to paleomagnetic observations

玛格丽特·S·埃弗里博士获得了NSF EAR博士后奖学金，在加州大学伯克利分校开展研究和教育活动。调查的重点是建立中生代地区(251-6550万年前)岩石的古地磁数据集的最新汇编，并进行数值地球发电机模拟。利用从火成岩中测得的地磁场强度数据，艾弗里博士探索了极性反转率与古地磁强度之间的关系。这项研究将先进的地球发电机模拟与扩大的古地磁观测联系起来，以便更好地了解地球演化重要时期的核心动力学和核幔边界条件。在教育活动中，埃弗里博士正在开发和教授一门“数据科学连接器”课程，重点是地球物理数据，特别是地磁学。此外，她还通过加州大学伯克利分校的女性物理科学学会指导一名本科生，并参加推广活动，例如向5-8年级的女孩介绍STEM领域职业的Expanding Your Horizons大会。地球磁场在广泛的时间尺度上变化。它在结构上是一阶偶极子，但偶极的变化是强度和极性。极性反转的速度在数千万年的时间尺度上有所不同。例如，在过去的20Myr中，磁场每百万年发生了~4次反转，而在白垩纪正极性超时期间，38Myr没有发生极性反转。在侏罗纪，反转速度远远高于现在的速度(每百万年最多有14次反转)。这些反转速率的剧烈变化发生在如此长的周期内，以至于它们很可能与地幔中调制外核流动的缓慢变化有关，从而提供了关于地球热演化的信息。在平均场强较高的时候，反转率很低；相反，在平均场强较低的时候，反转率很高。艾弗里博士使用了改进后的观测约束和一套新的数值地球发电机数值模拟。地球发电机软件Calypso被用来探索导致这些不同的地磁场行为的核心动力学和核幔相互作用，并检验极性反转率与古强度之间的假设正相关性。

Dr. Margaret S. Avery has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education activities at the University of California - Berkeley. The investigation focuses on building an updated compilation of paleomagnetic datasets for rocks from the Mesozoic area (251 - 65.5 million years ago) and running numerical geodynamo simulations. Using the geomagnetic field strength data measured from igneous rocks, Dr. Avery explores the relationship between polarity reversal rate and paleomagnetic field strength. This research links advanced geodynamo simulations with expanded paleomagnetic observations to enable better understanding of core dynamics and core-mantle boundary conditions during an important period of Earth evolution. For the education activities, Dr. Avery is developing and teaching a "Data Science Connector" course focused on geophysical data, specifically geomagnetism. In addition, she mentors an undergraduate student through the UC Berkeley's Society of Women in the Physical Sciences, and participates outreach activities, like the Expanding Your Horizons conference that introduces 5th-8th grade girls to careers in STEM fields.The Earth's magnetic field varies on a broad range of timescales. It is to first order dipolar in structure, but the dipole varies is strength and polarity. The rate of polarity reversals varies on time-scales of tens of millions of years. For example, the magnetic field has reversed ~4 times per million years over the past 20 Myr, whereas no polarity reversals occurred for 38 Myr during the Cretaceous normal-polarity superchron. During the Jurassic, the reversal rate was much higher than the present rate (up to 14 reversals per million years). These drastic changes in reversal rate occur on such long periods that they likely are related to slow changes in the mantle that modulate the outer-core flow, providing information about Earth's thermal evolution. During times when the field strength was higher on average the reversal rate was low; in contrast, during times when the field strength was lower on average there was a high rate of reversals. Dr. Avery uses improved observational constraints and a new suite of numerical geodynamo numerical simulations. The geodynamo software Calypso is used to explore core dynamics and core-mantle interactions that could cause these differing geomagnetic field behaviors, and to test the hypothetical positive correlation between polarity reversal rate and paleointensity.