| 项目编号: | 1606014
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| 项目名称: | The Differences in Onset Times of Hemispherically Conjugate Auroral Stations |
| 作者: | James Weygand
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| 承担单位: | University of California-Los Angeles
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| 批准年: | 2016
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| 开始日期: | 2016-09-01
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| 结束日期: | 2018-08-31
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| 资助金额: | 145505
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| 资助来源: | US-NSF
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| 项目类别: | Standard 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 - Atmospheric and Geospace Sciences
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| 英文关键词: | project
; difference
; onset
; onset time
; earth
; substorm onset
; auroral image
; timing difference
; pilot study
; true substorm-related timing difference
; conjugate all-sky imager
; onset difference
; significant difference
; auroral feature
; southern auroral region
; substorm onset signature
; hemispheric difference
; auroral emission
; other auroral event
; slight inter-hemispheric difference
|
| 英文摘要: | This is a one-year pilot study of a project classified as "high risk - high reward". The project will study hemispheric differences in the onset times of individual substorms and other auroral events observed simultaneously in the northern and southern auroral regions. Magnetic substorms (as they are called) reshape the Earth's magnetotail far out in Geospace. This process explosively releases energy powering an immediate intensification of currents and energetic charge particle precipitation closer to Earth in the ionosphere at the foot points of the affected field lines, and an intensification of auroral emissions. The investigation will take advantage of recently completed pairings of magnetometer stations located at the two Earthward ends of magnetic field lines that thread through the Earth's magnetotail where substorms are initiated. Differences in timing as well as the sequence of auroral features that precede the onset in each hemisphere will provide new information about, and place additional constraints on, controversial and still intensely debated theories about the underlying physical process(es) responsible for these extremely dynamic events. Significant closure risk is introduced in this project (which has never before been attempted) by the need to separate out the difference in timing due to the substorm process itself in the magnetosphere from other sources of timing offsets, for example, due to slight inter-hemispheric differences in the propagation path of a substorm onset signature into the magnetometer field of view. Whether these additional sources of timing differences can be removed using auroral images or other information, and the true substorm-related timing differences extracted, is the primary focus of this pilot study. The high reward of this technique, if proven feasible, is a new view into a long standing Geospace puzzle that continues to hinder progress in understanding severe space weather in the Earth's vicinity. Progress is important because in the hazardous radiation environment in near-Earth space, astronauts carry human enterprises into space and satellites that are key to important societal infrastructures orbit. The intense abrupt changes in the magnetic field associated with these explosive events induce currents in the solid Earth threatening long-term damage and shorter-term (potentially dangerous) disruptions in the operation of electric power grids. This pilot study will provide an educational experience to an undergraduate and a graduate student, contributing to the development of the future scientific workforce.
The project is a statistical study that aims to identify significant difference between the hemispheres in the onset time for individual substorms as measured by signatures of the onset in ground-based magnetometers. Given this information, it may be possible to determine which of two prominent substorm models are more consistent with the timing observations. The second phase of the project will look to identify causes of the differences by examining the orientation of the interplanetary magnetic field, solar wind conditions, and the Universal Time during the substorm onset. A smaller study will compare onset differences with those observed in a pair of conjugate all-sky imagers, when available. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/91363
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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: | |
James Weygand. The Differences in Onset Times of Hemispherically Conjugate Auroral Stations. 2016-01-01.
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