CEDAR: High Speed Spectroscopic Studies of lightning bolts: Starters, Jets, and Gigantic Jets

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项目编号	1755513
	CEDAR: High Speed Spectroscopic Studies of lightning bolts: Starters, Jets, and Gigantic Jets
	Ningyu Liu
主持机构	University of New Hampshire
项目开始年	2017
	2017-05-12
项目结束日期	2019-01-31
资助机构	US-NSF
项目类别	Continuing grant
项目经费	298371(USD)
国家	美国
语种	英语
英文摘要	The Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) program, a broad-based, community-guided, upper atmospheric research program, seeks to understand the behavior of atmospheric regions from the lower atmosphere upward through the ionized upper layers of the atmosphere. Of particular interest is the question of the scale of coupling of the lower atmosphere, where phenomena such as thunderstorms exist, to the ionized layer near 100-120 km. The physics of lightning phenomenology within thunderstorm events are very complex and highly time-dependent with complex morphology characterizing the coupling of lightning bolts to the ionosphere with consequential significant temporal behavior of the ionized density of the lower ionosphere region. These electrical discharges are initiated inside thunderstorms and are rooted in one of the main thundercloud charge layers. This award would study the physical processes underlying the particular transient lightning bolt structures referred to as blue starters, jets, and gigantic jets, which are the upward electrical discharges from thunderstorms that terminate at 20-30 km, 40-50 km and 70-90 km altitude, respectively. These are generated suddenly within a fraction of a second from thunderstorms. The research supported by this award would examine the energetics and dynamics of these TIL (Transient Luminous Event) phenomena. Typically, the initial vertical development has a speed of ~100 km/s, but after 100-300 ms, the upward discharge leading to gigantic jets suddenly accelerates to reach the lower ionosphere with a speed greater than 1000 km/s. The funded research would be primarily observational involving the construction of a high-speed (5,000 frames per second) spectrograph that can analyze the energetics of the jets and starters through the fast acquisition of visible atomic and molecular spectra allowing high-speed measurements of the relative intensities of the red-to-blue colors emitted by the lightning bolt along its path between the storm and the ionized layer. Analysis of these spectra would provide the time variations of the vertical temperature profile within the ionized air pathway of the lightning bolt. This information about the temperature profile would be used to quantify the energetics underlying the formation of these morphological features of the lightning bolt. This award has the potential of transformative research that would provide a major advance in the knowledge and understanding of the physics of transient plasma discharges which should prove to be extremely valuable and of high importance to the study of laboratory electrical discharges and tropospheric lightning investigations; such findings would be of great value to other disciplines such as power transformers, laser fusion research, and plasma discharge systems. The award would support significant activity in STEM education and student training similar to that recently conducted by the PI and his group. Finally, this award has a strong potential of attracting public attention via local TV and newspaper interviews. The grant awardees indicated also that they would provide the public with excellent public access to the research with frequent open lectures that would generate strong interest by the public in lightning phenomena. The award represents a strong potential for exciting and transformative science. The proposed research would examine in detail fundamental science questions that are related to jet and starter dynamics and their electrical coupling between the lower atmosphere and ionosphere. Moreover, the proposed observational approach is sophisticated providing critical high-time resolution spectral information on the spectral properties of starters and jets that would be studied to produce height profiles of temperature along the path of the conductive path between the top side of the thunderstorm and the lower ionosphere region established by the lightning bolt.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/71040
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Ningyu Liu.CEDAR: High Speed Spectroscopic Studies of lightning bolts: Starters, Jets, and Gigantic Jets.2017.