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

地球磁场是地球系统的一个重要元素，因为它有助于我们星球的宜居性。它的存在保护了表面环境不受来自太阳的带电粒子的影响。然而，磁场的起源位于液态金属核心的深处，在那里它不断地由湍流流体运动产生。人们对这一生成过程的许多方面知之甚少。来自最近的卫星飞行任务的大量数据为探测产生过程创造了新的机会。该项目的目标是将数据科学中的现代方法与最近的卫星观测相结合，以探测液态金属核心中的波。这些波导致了磁场的时间变化，并提供了对潜在动态的更广泛的洞察。这些洞察力使我们能够理解产生过程，从而能够预测磁场的变化(很像天气预报)。目标是评估在保护地表环境方面的变化，这对社会有利。该项目还支持对地球系统的基础研究，并支持对代表不足的群体进行STEM学科的教育。卫星观测大大提高了可从磁场中恢复的信息的质量。在过去的几年里，对二次时间导数(称为长期加速度)的可靠估计已经变得可行，这些记录非常适合于探测岩心顶部的波。这项研究使用了一种称为动态模式分解的方法来从海量卫星数据中提取波。波的探测和波速的恢复提供了关于岩心顶部条件的独特信息。许多候选海浪依赖于岩心顶部的层结，因此对海浪的探测可以对层结的强度提供很强的约束。归根结底，这些问题与地核和地球作为一个整体的地质演化有关。地幔对流的强度或化学作用的程度等因素有助于形成核-地幔边界的条件。虽然长期加速的有用记录必然仅限于卫星时代(过去20年)，但观测到的波动持续时间意味着，可用记录现在足以提取对我们星球动态的新见解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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 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.