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

EAR-PF：中生代地磁场行为：通过调整数值地球发电机模拟到古地磁观测来探索中生代核心动力学

基本信息

批准号：
1725798
负责人：
Margaret Avery
金额：
$ 10.86万
依托单位：
Avery Margaret S
依托单位国家：
美国
项目类别：
Fellowship Award
财政年份：
2017
资助国家：
美国
起止时间：
2017-11-01 至 2020-04-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1725798&HistoricalAwards=false
关键词：
EAR PF Mesozoic Geomagnetic Field

项目摘要

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.

Margaret S.艾弗里已被授予NSF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。调查的重点是建立一个更新的汇编古地磁数据集的岩石从中生代地区（251 - 6550万年前）和运行数值地球发电机模拟。利用从火成岩中测量的地磁场强度数据，艾弗里博士探索了极性反转率与古地磁场强度之间的关系。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。对于教育活动，Avery博士正在开发和教授一门专注于地球物理数据，特别是地磁数据的“数据科学连接器”课程。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，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。地球磁场在很大的时间尺度上变化。它是一阶偶极结构，但偶极的强度和极性不同。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2000万年里，磁场每百万年反转约4次，而在白垩纪正极性超时期的3800万年里没有发生极性反转。在侏罗纪时期，地球自转的速率比现在的速率要高得多（每百万年可达14次）。这些反转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，这些变化调节了外核流动，提供了有关地球热演化的信息。在平均场强较高的时间期间，反转率较低;相反，在平均场强较低的时间期间，反转率较高。艾弗里博士使用改进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被用来探索核心动力学和核幔相互作用，可能会导致这些不同的地磁场行为，并测试假设的正相关性极性反转率和古强度。