NSFGEO-NERC: CSEDI-On the origin of extreme variations in Earth's magnetic field

NSFGEO-NERC：CSEDI-论地球磁场极端变化的起源

• 批准号: 1953778
• 负责人: Catherine Constable
• 金额: $ 41.59万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1953778&HistoricalAwards=false
• 关键词: NSFGEO; NERC; CSEDI; origin; extreme

This is a project that is jointly funded by the National Science Foundation’s Directorate of Geosciences (NSF/GEO) and the National Environment Research Council (UKRI/NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award, each Agency funds the proportion of the budget and the investigators associated with its own ivestigators and component of the work.Earth’s internal magnetic field is generated deep in the planet’s liquid outer core and provides many benefits to its human inhabitants. It serves as a protective shield from the space weather generated by the solar wind, inhibits potentially damaging cosmic rays from reaching the surface, and has long served as a fundamental aid for navigation. Knowledge of its current structure is an intrinsic part of the digital mapping tools embedded in every smartphone, highlighting the importance of understanding what causes any unexpected changes. Extreme changes in both direction and strength of the magnetic field have occurred in the geological and archeological records, in the form of geomagnetic excursions, polarity reversals, and rapid intensity variations known as geomagnetic spikes. These will be studied under this project. An integral aspect of the work will be building synergistic approaches across communities interested in the geological record of the magnetic field and realistic computational simulations of its behavior. Understanding the physical origins of these changes will enhance our basic understanding of Earth’s magnetic field, and enable collaborations with related geophysical communities interested in Earth’s deep interior and other planets. New methodologies will be developed to study extreme changes in the geomagnetic field and this project will enable education, training and research mentoring for undergraduate, graduate, and postdoctoral researchers, while developing further international collaborations with NERC sponsored investigators at Leeds University, UK. This work will improve understanding of what drives extreme events using two synergistic components. A multi-scale modeling approach based on spherical triangle tessellations (STT) on the surface of Earth’s core will improve regional resolution in global magnetic field models. A new suite of geodynamo models will access the rapidly rotating regime appropriate to Earth’s liquid core. The results will be combined to assess potential physical interpretations of empirical signatures of extreme events. Extreme field variations present a challenge to standard regularized spherical harmonic representations which rely on trade-offs between data misfit and global measures of spatial and temporal complexity. The STT representation will allow finer spatial and temporal resolution in regions of high data density and lower resolution with limited data, enabling robust imaging of extreme regional field behavior. A new regime diagram describing the behavior of non-magnetic convection with Earth-like geometry, buoyancy forcing, and heat flow heterogeneity at the outer boundary illuminates the parameter combinations needed for simulations to realize the rapidly rotating and turbulent dynamics that are thought to arise in the liquid core. Recent advances in dynamo theory will be used to devise simulations that produce strong magnetic forces as likely occur in the core, following a distinct path towards Earth-like rotation rates and diffusivities while remaining in the rapidly rotating regime. Both new and existing tools will be used to assess the morphological and temporal similarity between these simulations and new geomagnetic field models, characterize extreme changes in intensity and direction of the observable field, and relate these to the underlying magnetohydrodynamic processes.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.

这是一个由国家科学基金会地球科学理事会（NSF/GEO）和联合王国国家环境研究理事会（UKRI/NERC）通过NSF/GEO-NERC牵头机构协议共同资助的项目。该协议允许美国/英国提交一份联合提案，并由研究者拥有最大预算比例的机构进行同行评审。一旦成功地共同确定了一个奖项，每个机构都为预算的一部分和与自己的调查人员和工作组成部分有关的调查人员提供资金。地球的内部磁场产生于地球液态外核深处，为人类居民提供了许多好处。它可以作为太阳风产生的空间天气的保护屏障，抑制潜在的破坏性宇宙射线到达表面，并长期以来一直作为导航的基本辅助工具。了解其当前结构是嵌入在每部智能手机中的数字地图工具的固有组成部分，这突出了了解导致任何意外变化的原因的重要性。在地质学和考古学的记录中，磁场的方向和强度都发生了极端的变化，表现为地磁漂移、极性反转和被称为地磁尖峰的快速强度变化。这些将在本项目下进行研究。这项工作的一个组成部分将是在对磁场的地质记录和其行为的现实计算模拟感兴趣的社区之间建立协同方法。了解这些变化的物理起源将增强我们对地球磁场的基本理解，并使对地球内部深处和其他行星感兴趣的相关地球物理团体能够合作。 将开发新的方法来研究地磁场的极端变化，该项目将为本科生，研究生和博士后研究人员提供教育，培训和研究指导，同时与英国利兹大学的NERC赞助研究人员开展进一步的国际合作。这项工作将利用两个协同作用的组成部分，提高对极端事件驱动因素的理解。基于地核表面球面三角形镶嵌（STT）的多尺度建模方法将提高全球磁场模型的区域分辨率。一套新的地球发电机模型将进入适合地球液核的快速旋转状态。这些结果将被结合起来，以评估极端事件的经验特征的潜在物理解释。 极端场变化对标准正则化球谐表示提出了挑战，该标准正则化球谐表示依赖于数据失配与空间和时间复杂性的全局度量之间的权衡。STT表示将允许在高数据密度区域中具有更精细的空间和时间分辨率，并且在有限数据的情况下具有较低的分辨率，从而实现极端区域场行为的稳健成像。一个新的状态图描述的行为与地球一样的几何形状，浮力强迫，热流的不均匀性在外边界的非磁对流照亮的参数组合需要模拟实现快速旋转和湍流动力学，被认为是出现在液核。发电机理论的最新进展将被用来设计模拟，产生强大的磁力可能发生在核心，遵循一个独特的路径对地球一样的旋转速率和扩散率，同时保持在快速旋转的制度。新的和现有的工具都将用于评估这些模拟与新的地磁场模型之间的形态和时间相似性，描述可观测场强度和方向的极端变化，该奖项反映了NSF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进行评估，被认为值得支持的搜索.

项目成果

Can machine learning reveal precursors of reversals of the geomagnetic axial dipole field?

• DOI: 10.1093/gji/ggac195
• 发表时间: 2022-05
• 期刊: Geophysical Journal International
• 影响因子: 2.8
• 作者: K. Gwirtz;T. Davis;M. Morzfeld;C. Constable;A. Fournier;G. Hulot

Indicators of mantle control on the geodynamo from observations and simulations

观测和模拟中地幔对地球发电机的控制指标

• DOI: 10.3389/feart.2022.957815
• 发表时间: 2022
• 期刊: Frontiers in Earth Science
• 影响因子: 2.9
• 作者: Korte, Monika;Constable, Catherine G.;Davies, Christopher J.;Panovska, Sanja
• 通讯作者: Panovska, Sanja

A new power spectrum and stochastic representation for the geomagnetic axial dipole

地磁轴向偶极子的新功率谱和随机表示

• DOI: 10.1093/gji/ggac172
• 发表时间: 2022
• 期刊: Geophysical Journal International
• 影响因子: 2.8
• 作者: Sadhasivan, Mayuri;Constable, Catherine
• 通讯作者: Constable, Catherine