Collaborative Research: Exploiting Geomagnetic Records to Describe Past and Present Ocean Variability

合作研究：利用地磁记录来描述过去和现在的海洋变化

• 批准号: 2402116
• 负责人: David Trossman
• 金额: $ 11.13万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-10-01 至 2025-09-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2402116&HistoricalAwards=false
• 关键词: Collaborative; Research; Exploiting; Geomagnetic; Records; Collaborative; Research; Exploiting; Geomagnetic; Records

The electrically conducting ocean generates electric currents and associated magnetic fields as it flows through the Earth’s magnetic field. These electric currents vary in time with changes in the ocean’s electrical conductivity and velocity, and can be detected remotely by land and satellite magnetometers. There is therefore an opportunity to recover ocean flow and conductivity variability from magnetometer data. Extracted signals are very useful, as they represent depth integrals of conductivity and conductivity transport, which can stand as proxies for heat content and heat transport over the measurement durations – quantities that have been hard to measure with other methods. Magnetometer data come from hundreds of land magnetic observatories (some with hourly data extending back a century) as well as from modern satellite magnetic surveys. The proposed work will extract past ocean variability from long, land geomagnetic observatory records, develop forward models for predicting the oceanic magnetic fields, and ultimately develop data assimilation strategies for both land and satellite observations. This project will examine both fundamental components of ocean electrodynamics and exploit a new data type for monitoring and understanding ocean variability and steric sea-level changes. The electromagnetic field modules in the model used here will be made publicly available. Workshops will be organized to introduce students and early career scientists to analysis of geomagnetic observatory data and its connection to oceanographic applications.Extracting oceanic signals from magnetic data is challenging because the signals are relatively weak and a priori knowledge of the signal is required. This proposal demonstrates method feasibility with preliminary work on a century of ocean tidal variability extracted from the Honolulu geomagnetic observatory data. These independent data confirm a trend toward increasing tidal amplitudes previously found in Honolulu tide gauge data that has been attributed to ocean warming. The Honolulu series will be thoroughly analyzed to optimize the extraction of ocean tidal signals. The methods will be extended to extract other predictable ocean signals there, such as inertial oscillations and interannual oscillations. Similar methods will be applied to geomagnetic observatory data from other locations. Extensions will include canonical-correlation multivariate analyses of data from multiple locations as well as from satellite data and geomagnetic field models. Additional tasks will involve the development and use of forward models to calculate the magnetic (and electric) fields given tidal and circulation ocean model flow. Extracted signals represent depth integrals of conductivity and conductivity transport, useful as proxies for heat content and heat transport over the measurement durations – quantities that have been hard to measure with other methods. Thus, in addition to addressing fundamental components of ocean electrodynamics the proposed work will be useful in exploiting a new data type for monitoring and understanding ocean variability and steric sea-level changes.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.

电子传导海洋在流过地球磁场时会产生电流和相关的磁场。这些电流随着海洋电导率和速度的变化而随着时间的变化而变化，可以通过陆地和卫星磁力计远程检测。因此，有机会从磁力计数据中恢复海洋流量和电导率变化。提取的信号非常有用，因为它们代表了电导率和电导率传输的深度积分，可以在测量持续时间内用作热含量和热传输的代理 - 用其他方法很难测量的数量。磁力计数据来自数百个土地磁观测（有些带有每小时延伸到一个世纪的数据）以及现代卫星磁性调查。拟议的工作将从长长的土地地磁观测记录中提取过去的海洋变异性，开发用于预测海洋磁场的前向模型，并最终为土地和卫星观测而制定数据同化策略。该项目将检查海洋电动力学的基本组成部分，并利用一种新的数据类型来监视和了解海洋可变性以及空间海平面变化。此处使用的模型中的电子场模块将公开可用。研讨会将组织为介绍学生和早期的职业科学家，以分析地磁观察数据及其与海洋应用的联系。从磁数据中提取海洋信号是挑战的，因为信号相对较弱，并且需要对信号的先验知识。该提案证明了从檀香山地磁观察数据中提取的一个世纪的海洋潮汐变异性的初步工作的方法可行性。这些独立的数据证实了增加了归因于海洋变暖的檀香山潮汐量规数据中以前发现的潮汐放大器的趋势。檀香山系列将进行彻底分析，以优化海洋潮汐信号的提取。这些方法将扩展到其中提取其他可预测的海洋信号，例如惯性振荡和年际振荡。类似的方法将应用于其他位置的地磁观察数据。扩展将包括来自多个位置的数据以及卫星数据和地磁场模型的规范相关多元分析。其他任务将涉及在潮汐和循环海洋模型流动下计算磁性（和电气）场的开发和使用。提取的信号代表了电导率和电导率传输的深度积分，可作为在测量持续时间内进行热含量和热传输的代理 - 数量很难用其他方法测量。除了解决海洋电动力学的基本组成部分外，拟议的工作将有助于利用新的数据类型，以监视和了解海洋可变性和空间海平面的变化。该奖项反映了NSF的法定任务，并被认为是通过使用基金会的知识分子和更广泛影响的评估来审查Criteria来通过评估来通过评估来获得支持的。