Studying the Magnetic Signature of the Inner Core

Earth’s magnetic field acts as a protective shield for the planet, which is essential for keeping it habitable. However, this shield may not have always been as strong as it is today. Rocks formed between 700 and 550 million years ago contain evidence of an unstable and extremely weak magnetic field. This was also the time some estimate that the Earth’s liquid iron core began to solidify, forming the solid inner core we have today. This project will conduct a statistical analysis of magnetic data from that era to look for changes in the field’s behavior. In parallel, the project will create computer models to simulate how the magnetic field was generated as the core began to solidify. By comparing the models with the physical data, the project will determine if the start of core solidification caused instability in the magnetic field. The project will further benefit society through contributing to public engagement through a series of public lectures and K-12 outreach activities. The goal of this proposal is to identify the paleomagnetic signature of Earth's inner core formation by performing a statistical comparison of paleomagnetic data to evolving numerical dynamo models. Inner core nucleation (ICN) is predicted to have occurred around 600 million years ago - a time when the geodynamo was close to dying. Paleointensity data show a potential jump around the expected time of ICN, motivating a detailed comparison with evolving numerical dynamos. The project will perform a statistical analysis of existing paleomagnetic intensities and directions from two open-source databases, compute new evolving 3D numerical dynamo models driven to make predictions for the magnetic field behavior around the time of ICN, and perform a statistical comparison between the numerical models and paleomagnetic data. Project outcomes will facilitate a better understanding of the generation and evolution of the global magnetic field, which is crucial to how Earth interacts with the Solar Wind, modern-day satellite safety, and global navigation. 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.