Data-driven detection of waves in Earth's core and geophysical interpretation

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

Earth’s magnetic field is an important element of the Earth system because it contributes to the habitability of our planet. Its existence protects the surface environment from charged particles that stream from the Sun. However, the origins of the magnetic field lie deep inside the liquid metal core, where it is continually generated by turbulent fluid motions. Many aspects of this generation process are poorly understood. Vast quantities of data from recent satellite missions create new opportunities to probe the generation process. The goal of this project is to combine modern methods in Data Science with the recent satellite observations to detect waves in the liquid metal core. These waves contribute to time variations in the magnetic field and provide broader insights into the underlying dynamics. These insights inform our understanding of the generation process, which enables predictions of changes in the magnetic field (much like weather forecasts). The objective is to assess changes in the protection of our surface environment, which benefits society. The project also supports fundamental research into the Earth system and supports the education of underrepresented groups in STEM disciplines. Satellite observations have substantially improved the quality of information that can be recovered from the magnetic field. Reliable estimates for the second time-derivative (known as secular acceleration) have become feasible in the past few years, and these records are well suited for detecting waves at the top of the core. This study uses a method known as dynamic mode decomposition to extract waves from huge volumes of satellite data. Detection of waves, and the recovery of the wave speeds, provides unique information about conditions at the top of the core. Many of the candidate waves depend on stratification at the top of the core, so detection of waves can offer strong constraints on the strength of stratification. Ultimately these questions are related to the geological evolution of the core and Earth as a whole. Factors such as the vigor of mantle convection or the extent of chemical interactions contribute to conditions at the core-mantle boundary. While useful records of secular acceleration are necessarily restricted to the satellite era (last twenty years), the duration of observed fluctuations means that the available record is now sufficient to extract novel insights into the dynamics of our planet. 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.