| 项目编号: | 1644644
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| 项目名称: | Interpreting the Paleomagnetic Field Using Stochastic Models |
| 作者: | Bruce Buffett
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| 承担单位: | University of California-Berkeley
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| 批准年: | 2017
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| 开始日期: | 2017-01-01
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| 结束日期: | 2019-12-31
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| 资助金额: | 180000
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| 资助来源: | US-NSF
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| 项目类别: | Continuing grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Geosciences - Earth Sciences
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| 英文关键词: | magnetic field
; stochastic model
; paleomagnetic observation
; dipole field
; duration
; physical modeling
; work
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| 英文摘要: | Earth's magnetic field is an important aspect of our planet's habitability, yet the long-term behavior of the magnetic field is poorly understood. Historical observations provide a valuable source of information, but the duration of this record is just too short to draw meaningful conclusions. Instead, we must rely on paleomagnetic observations to build a more complete understanding. Unfortunately, the link between paleomagnetic observations and the underlying dynamics is neither simple nor direct. A promising new strategy will be developed using stochastic models to quantify the time dependence of the dipole field. This approach is ideally suited for the task because it focuses on the observed part of the field (i.e. the dipole), while treating the unobserved part of the magnetic field in a statistical fashion. The expected outcome of this work is two-fold. First, the stochastic models will enable the investigators to make quantitative predictions for many properties of the magnetic field, including the rates of reversal in the dipole polarity as well as the duration of short disruptions in the magnetic field (often called excursions). Second, the stochastic models are amenable to physical interpretation, which means that the team can make important advances in connecting paleomagnetic observations to physical processes deep inside the planet. Engagement of graduate and senior undergraduate students in the project will promote skills in physical modeling, data analysis, statistics, and high-performance computing.
The proposed work identifies four main tasks. The first step is to construct stochastic models using observations of the dipole field over the past two million years. Predictions for the power spectrum of dipole fluctuations can be related to physical properties, like the electrical conductivity of the core or the overturn time for convection. The second task will address the autocovariance of the observed dipole fluctuations. Turbulent motions in Earth's core drive random fluctuations in the dipole field, so detailed estimates of the autocovariance offer unique insights into the mechanisms of dipole generation. The third task deals with the duration of polarity transitions with the aim of identifying timescales and processes at work during reversals. Finally, the investigators will quantitatively assess the relative occurrence of short chrons under the hypothesis that they represent polarity transitions when the initial state is not fully established in a stable polarity. At each stage they will assess the success or failure of the models by making detailed comparisons with available observations. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/90699
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| Appears in Collections: | 全球变化的国际研究计划
科学计划与规划
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| Recommended Citation: | |
Bruce Buffett. Interpreting the Paleomagnetic Field Using Stochastic Models. 2017-01-01.
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