Detecting and Inverting Magnetic Waves for the Structure and Dynamics of Earth's Core

已知地球内部磁场的波动会在很宽的时间尺度上发生。在地质记录中，大约以几十万年的不规则间隔检测到磁场逆转，而现代地面观测显示磁场在短短几年内发生突然变化。最近卫星任务的高保真度记录现在表明，磁场的突然变化比以前认为的更频繁。这些事件影响了我们预测磁场的能力，但对这些扰动的起源知之甚少。 一个可行的解释是地核顶部的波浪。研究人员发现了几种类型的波，可以解释磁扰动的周期和空间模式。本研究的目的是检测这些波的地磁观测和恢复估计的波传播速度。这些信息将增强我们预测磁场的能力，也将为地球核心的物理状态提供独特的见解，这将提高我们对磁场如何由核心对流产生的理解。 该项目将支持加州大学伯克利分校一名西班牙裔研究生的研究。将向该学生介绍先进的数据分析和计算方法，以及并行计算和科学可视化，研究人员建议利用SWARM卫星的观测来确定地核赤道区域快速地磁波动的起源。他们假设这些波动是地核顶部波浪的结果，并计划采用几种类型的波浪模型来解释地磁信号。研究人员打算使用波动模型来提取有关核幔边界附近普遍存在的物理条件的信息，包括可能存在的稳定分层。他们还试图描述波的源机制，因为它将波的振幅与核心深处的对流过程联系起来。研究人员还计划利用地磁场时间变化的高保真记录来寻找地核-地幔边界地形的证据。恢复有关地核-地幔边界的地形信息将对最低mantle.This奖项对流的风格提供意想不到的约束反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Fluctuations in the Earth's internal magnetic field are known to occur over a broad range of time scales. Magnetic reversals are detected in the geological record at irregular intervals of roughly several hundred thousand years, whereas modern ground-based observations reveal abrupt changes in the magnetic field over just a few years. Higher fidelity records from recent satellite missions now suggest that the abrupt changes in the magnetic field occur more frequently than previously believed. These events affect our ability to forecast the magnetic field, yet the origin of these disturbances is poorly understood. One viable interpretation involves waves at the top of the core. The investigators have found several types of waves that account for the periods and spatial patterns of the magnetic disturbance. The goal of this research is to detect these waves in geomagnetic observations and to recover estimates for the wave propagation speeds. This information will enhance our ability to forecast the magnetic field, and it will also provide unique insights into the physical state of the Earth's core, which will improve our understanding of how the magnetic field is generated by convection in the core. The project will support the research of a Hispanic graduate student at the University of California, Berkeley. This student will be introduced to advanced data analysis and computational methods, as well as parallel computing and scientific visualization.The investigators propose to use observations from the SWARM satellite to identify the origin of rapid geomagnetic fluctuations in the equatorial region of the Earth's core. They hypothesize that these fluctuations are a result of waves at the top of the core, and plan to adopt several types of wave models to interpret the geomagnetic signals. The investigators intend to use the wave models to extract information about the physical conditions that prevail near the core-mantle boundary, including the possible presence of stable stratification. They also seek to characterize the source mechanism for the waves because it connects the wave amplitudes to convective processes deeper in the core. The researchers also plan to search for evidence of topography on the core-mantle boundary using high-fidelity records of time variations in the geomagnetic field. Recovery of information about the topography on the core-mantle boundary would offer unexpected constraints on the style of convection in the lowermost mantle.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.