CSEDI: Understanding the influence of mantle dynamics on the generation of Earth's magnetic field throughout the plate tectonics cycle.

地球的磁场起到了屏蔽宇宙辐射和磁暴的作用，这可能会破坏技术基础设施，危害生命，并剥离地球的大气层。因此，了解磁场的演变对今天和整个历史上地球的宜居性具有重要意义。目前限制对磁场演化理解的一个突出问题是：固体内核是什么时候形成的？今天，内核的凝固是地球发电机的一个重要驱动力，它产生了地球的磁场。该项目旨在更好地限制内核形成的时间，这将通过独特的地幔对流模型与产生类似地球磁场的地球动力学模拟的耦合来完成。这个项目的成果将对多个学科产生科学影响，包括地球动力学、磁层物理学、深层内部研究和生命进化。更一般地说，这个项目解决了“地球内部磁场是如何产生的？”，这有助于更好地预测未来可能对现代技术基础设施或生命本身造成危害的磁场变化。此外，拟议的工作将支持两名早期职业女性pi，通过培训和教育两名本科生和一名博士后研究员来培养STEM人才，通过将创建的软件作为开源发布来改善现有的科学基础设施，并将促进与英国和法国的项目合作者的国际交流。在与佛罗里达大学汤普森地球系统研究所合作的成功的“佛罗里达每所学校的科学家”项目的基础上，通过一项多年的外展倡议，将广泛吸引观众。因为内核的增长是今天地球发电机的主要驱动力，所以可以假设内核的成核可能导致了地球过去磁场的重大变化。但迄今为止，对地球表面古地磁数据中任何可探测信号的解释仍然模糊不清，因为(1)内核成核对磁场的精确影响尚不清楚；(2)地幔对流引起的磁场变化幅度目前尚未得到很好的约束。本项目将量化地幔热输运对地球表面磁场可能产生的最大影响，同时考虑到内核大小的影响。这将通过计算由地幔对流模型产生的真实的核心-地幔边界热通量模式来完成，并将它们与产生类地磁场的地球动力学模拟相结合，并根据古地磁模拟质量（QPM）标准进行评估，这是目前评估模拟是否再现地球长期磁场行为的唯一标准。与以前的研究相比，这些地幔模型并没有试图重建已知板块运动的相对有限的时间框架，也没有将简化的热通量模式应用于当今的条件，而是预测了地球过去超大陆形成和扩散周期中由合成板块构造引起的最大的现实热通量变化。这项工作将提高对地幔在整个地球历史中调节磁场的作用的理解。此外，这项工作将确定迄今为止归因于内核成核的磁场变化是否可以部分或完全由地幔动力学单独解释。该项目将行星演化、地幔对流、地球动力学和古地磁数据联系起来。这种广泛的合作将推动对地球作为一个系统的理解取得重大进展，而不是被分成几层。更一般地说，这个项目解决了科学优先问题，“地球内部磁场是如何产生的？”，发表在美国国家科学院、工程院和医学院为NSF-EAR编写的十年报告中。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Earth's magnetic field acts as a shield against cosmic radiation and magnetic storms, which can potentially damage technical infrastructure, harm life, and strip away Earth's atmosphere. Understanding the evolution of the magnetic field therefore has important implications for Earth's habitability today and throughout history. An outstanding question that currently limits understanding of the evolution the magnetic field is: When did the solid inner core form? Today, the solidification of the inner core is an important driver of the geodynamo, which generates Earth’s magnetic field. This project seeks to better constrain the timing of inner core formation, which will be accomplished by a unique coupling of mantle convection models to geodynamo simulations that produce Earth-like magnetic fields. The results from this project will have a scientific impact in multiple disciplines, including geodynamics, magnetospheric physics, studies of the deep interior, and the evolution of life. More generally, this project addresses the important question of “How is Earth’s internal field generated?”, which can help to better predict future magnetic field changes that could result in harm to modern technical infrastructure or life itself. Additionally, the proposed work will support two early-career female PIs, build STEM talent by training and educating two undergraduate students and one postdoctoral researcher, improve available scientific infrastructure by releasing the created software as open-source, and will facilitate international exchange with project collaborators in the UK and France. A wide audience will be engaged through a multi-year outreach initiative building on the successful Scientist in Every Florida School program in collaboration with University of Florida Thompson Earth Systems Institute.Because the growth of the inner core is a major driver of the geodynamo today, it can be assumed that inner core nucleation may have caused significant changes in Earth's past magnetic field. But so far, the interpretation of any detectable signal in the paleomagnetic data at the Earth’s surface has remained ambiguous because (1) the precise effects of inner core nucleation on the magnetic field are unknown, and (2) the magnitude of magnetic field variations caused by mantle convection are currently not well constrained. This project will quantify the largest possible influence of mantle heat transport on the magnetic field at Earth’s surface, taking into account the influence of inner core size. This will be accomplished by computing realistic core-mantle boundary heat flux patterns generated by mantle convection models, and coupling them to geodynamo simulations that produce Earth-like magnetic fields as assessed with the Quality of Paleomagnetic Modeling (QPM) criteria, which is currently the only criteria set that assesses if simulations are reproducing Earth’s long-term magnetic field behavior. In contrast to previous studies, these mantle models do not try to recreate the relatively limited timeframe of known plate motions, or apply simplified heat flux patterns for present-day conditions, but instead predict the largest realistic heat flux variations caused by synthetic plate configurations during the cycle of supercontinent formation and dispersal in Earth's past. This work will improve understanding of the mantle’s role in regulating the magnetic field throughout Earth's history. Additionally, this work will determine whether changes in the magnetic field so far ascribed to inner core nucleation could instead partly or completely be explained by mantle dynamics alone. This project connects planetary evolution, mantle convection, the geodynamo, and paleomagnetic data. This wide collaboration will drive significant advances in the understanding of the Earth as one system, not separated into its layers. More generally, this project addresses the science priority question, “How is Earth’s internal field generated?”, released in the National Academies of Science, Engineering and Medicine decadal report for NSF-EAR.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.