The Differences in Onset Times of Hemispherically Conjugate Auroral Stations

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项目编号	1606014
	The Differences in Onset Times of Hemispherically Conjugate Auroral Stations
	James Weygand
主持机构	University of California-Los Angeles
项目开始年	2016
	2016-09-01
项目结束日期	2017-08-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	145505(USD)
国家	美国
语种	英语
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.
来源学科分类	Geosciences - Atmospheric and Geospace Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/70141
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	James Weygand.The Differences in Onset Times of Hemispherically Conjugate Auroral Stations.2016.