| 项目编号: | 1547263
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| 项目名称: | Accomplishment Based Renewal: Transforming the paleointensity experiment and application to the paleointensity database |
| 作者: | Lisa Tauxe
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| 承担单位: | University of California-San Diego Scripps Inst of Oceanography
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| 批准年: | 2017
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| 开始日期: | 2017-02-15
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| 结束日期: | 2020-01-31
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| 资助金额: | 125000
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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: | field strength
; paleointensity study
; precise paleointensity estimate
; paleointensity estimate
; paleointensity database
; robust experimental protocol
; long term aging experiment
; magic database
; pi
; poor experimental design
; new experimental method
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| 英文摘要: | The geomagnetic field has been dropping rapidly over the past century (8%)leaving some worried that it could collapse into what is known as a 'transitional state' with a strength of ~10% of the present field. Such an event would pose severe danger to the planet's electrical grid and satellites requiring some advanced planning. The likelihood of this happening is presently unknown as human measurements of the magnetic field strength span only the last ~150 years and fundamental questions regarding the average field strength of the geomagnetic field and its variation through time remain despite decades of effort. This project will serve to support the research of several students (both undergraduate and graduate), one of whom is an under-represented minority female. In addition, it will provide funding for a female computer programmer to continue efforts on improving the software supporting online materials including a textbook and a complete software package (PmagPy) that integrates smoothly with the MagIC database, (http://earthref.org/MAGIC/books/Tauxe/Essentials and http://earthref.org/PmagPy/cookbook respectively).
The signal of an axial geomagnetic dipole, whereby the field strength doubles from the equator to the poles, is readily apparent in the present field but no such clear dipolar signal exists in the paleointensity database from the last five million years. There are several possible explanations for this troubling failure: 1) combining data from different ages with possibly different average intensities leads to an inappropriate comparison of field states, 2) there is a depression of field strength at high latitude, perhaps reflecting the role of the 'tangent cylinder' or 3) there is noise and/or bias introduced by poor selection criteria or poor experimental design. The latter is a likely explanation as published data from the 1960 flow on Hawaii display the entire range of intensity values observed on the Earth's surface today, yet they should all have one distinct value. The PI has developed new experimental methods, better field strategies and a new approach to data selection that will allow the team to obtain accurate estimates of the ancient field strength to improve our understanding of the intensity behavior in Earth's past. The PI plans a comprehensive field campaign to collect samples targeting the most promising material for paleointensity study. These will be analyzed using the most robust experimental protocol and subjected to rigorous selection criteria proven to reject inaccurate results, leading to both accurate and precise paleointensity estimates. The PI will also complete a long term aging experiment of thermal remanence to investigate the contribution of bias (and
noise) of non-single domain material in the database, with an eye toward improving the experiment and data selection procedures leading to higher accuracy in paleointensity estimates. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/90518
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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: | |
Lisa Tauxe. Accomplishment Based Renewal: Transforming the paleointensity experiment and application to the paleointensity database. 2017-01-01.
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