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

Margaret S. Avery博士获得美国国家科学基金会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。研究的重点是建立一个更新的中生代（2.51 - 6550万年前）岩石的古地磁数据集，并进行数值地球动力学模拟。利用从火成岩中测量的地磁场强度数据，Avery博士探索了极性反转率和古磁场强度之间的关系。本研究将先进的地球动力学模拟与扩展的古地磁观测相结合，以便更好地了解地球演化重要时期的地核动力学和地核-地幔边界条件。在教育活动方面，Avery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。此外，她还通过加州大学伯克利分校的物理科学女性协会指导一名本科生，并参加拓展活动，比如“拓展你的视野”会议，该会议向5 -8年级的女孩介绍STEM领域的职业。地球磁场在很宽的时间尺度范围内变化。在结构上为一级偶极子，但偶极子的强度和极性各不相同。极性逆转的速率在数千万年的时间尺度上变化。例如，在过去的20 Myr中，磁场每百万年逆转约4次，而在白垩纪正常极性超时期间，38 Myr没有发生极性逆转。在侏罗纪时期，逆转率比现在高得多（每百万年高达14次逆转）。这些反转速率的剧烈变化发生在如此长的时间内，它们可能与地幔的缓慢变化有关，地幔调节了外核流动，提供了有关地球热演化的信息。平均场强较高时，磁极反转率较低；相反，在磁场强度平均较低的时期，磁极倒转率很高。艾弗里博士使用改进的观测约束和一套新的数值地球动力学数值模拟。地球动力学软件Calypso用于探索可能导致这些不同地磁场行为的核心动力学和核心-地幔相互作用，并验证极性反转率与古强度之间假设的正相关关系。

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.