Collaborative Research: CEDAR: Sprite Energetics

合作研究：CEDAR：雪碧能量学

• 批准号: 0334795
• 负责人: Hans Nielsen
• 金额: $ 18.63万
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-02-01 至 2007-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0334795&HistoricalAwards=false
• 关键词: Collaborative; Research; CEDAR; Sprite; Energetics

The objective of this research is to determine the amount of energy sprites deposit in the mesosphere. Sprites are large (~50km scale size) luminous events seen above thunderstorms. The investigators will make altitude resolved optical spectra at millisecond and higher time resolution. The observations will determine how sprites modify the mesosphere. Most sprites are associated with positive cloud to ground lighting strikes, and luminosity may extend from cloud tops up to ionospheric heights. Sprites lasts a few millisecond (ms) to 10's of ms with initiation commonly at an altitude of 70-75 km followed by both upward and downward propagation of luminosity. Sprites are predominantly red, but tendrils at low altitude are blue. Spectral measurements at TV frame rates (33 ms resolution) show the emissions to be from molecular nitrogen. Blue emissions from ionized nitrogen are expected to be present, but this has not been confirmed. The data available so far have not been able to answer firmly the central questions of how much energy is deposited into the mesosphere, and the resulting modification of the mesosphere by sprites. To address the time development of the energy deposition in sprites, the investigators will make spectral observations with ms time resolution. The primary instruments on a common mount will be an imaging slit spectrograph and two 16-channel multi-anode spectral photometers together with a TV imager to provide spatial context. The imaging spectrograph will provide better spectral resolution, while the spectral photometers will provide better temporal resolution. In addition, an imager will be deployed at a separate location to provide triangulated altitude information. The measurements will be compared to first principles models of sprite emissions to determine the energy deposition as a function of altitude and time. The investigators will also determine the amount of ionization and resulting changes in conductivity within the mesosphere caused by sprites. Two extended ground campaigns are planned. This research will provide clear understanding of sprite formation and propagation as a function of time and altitude. Spectral measurement will provide an unambiguous record of the neutral and ionized nitrogen emissions from sprites. Comparison of data obtained from this project with models of sprite emission will provide the time history of sprite energetics. The research will provide a balance of experimental and theoretical development suitable for a student working towards a PhD. The research plan also includes undergraduate cadets from the Air Force Academy in the calibration of the spectral photometers, and the gathering and analysis of the data. These experiences will provide the undergraduates a first hand look at real research, hopefully interesting them in further study at the graduate level. In addition the investigators plan a vigorous outreach program directed at high school students and teachers.

这项研究的目的是确定在中间层的能量精灵存款的数量。小精灵是在雷暴上方看到的大型（约50公里尺度）发光事件。研究人员将以毫秒和更高的时间分辨率制作高度分辨光谱。观测结果将确定精灵如何改变中间层。大多数精灵都与正云对地闪电有关，亮度可能从云顶延伸到电离层高度。精灵持续几毫秒（ms）到几十毫秒，通常在70 - 75公里的高度开始，然后向上和向下传播光度。精灵主要是红色的，但在低海拔卷须是蓝色的。在电视帧速率（33毫秒分辨率）的光谱测量显示的排放是从分子氮。来自电离氮的蓝色发射预计会出现，但这尚未得到证实。到目前为止，现有的数据还不能确切地回答有多少能量沉积到中间层以及精灵对中间层的影响等核心问题。为了解决精灵中能量沉积的时间发展，研究人员将以ms的时间分辨率进行光谱观测。在一个共同的安装主要仪器将是一个成像狭缝光谱仪和两个16通道多阳极光谱光度计与电视成像仪一起提供空间背景。成像光谱仪将提供更好的光谱分辨率，而光谱光度计将提供更好的时间分辨率。此外，还将在另一个地点部署一个成像仪，以提供三角测量的高度信息。测量结果将与精灵排放的第一原理模型进行比较，以确定作为高度和时间函数的能量沉积。研究人员还将确定电离量以及由精灵引起的中间层电导率的变化。计划开展两次大规模地面活动。这项研究将提供清晰的理解精灵的形成和传播作为时间和高度的函数。光谱测量将提供一个明确的记录中性和电离氮排放的精灵。从这个项目获得的数据与雪碧排放模型的比较将提供雪碧能量学的时间历史。该研究将提供实验和理论发展的平衡，适合攻读博士学位的学生。该研究计划还包括来自空军学院的本科学员校准光谱光度计，收集和分析数据。这些经验将为本科生提供一个真实的研究的第一手资料，希望他们在研究生阶段的进一步研究中感兴趣。此外，调查人员还计划针对高中学生和教师开展一项积极的外展计划。