CEDAR: Exploration of Trends in Thermospheric+Exospheric Hydrogen Using H-Alpha Emission Intensities and Hydrogen Column Abundances Retrieved from the Wisconsin Long Term Record

CEDAR：利用从威斯康星州长期记录中检索到的 H-Alpha 发射强度和氢柱丰度探索热层外层氢的趋势

• 批准号: 0334611
• 负责人: Susan Nossal
• 金额: --
• 依托单位: University of Wisconsin-Madison
• 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: 2004-01-15 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0334611&HistoricalAwards=false
• 关键词: CEDAR; Exploration; Trends; Thermospheric+Exospheric; Hydrogen

Upward fluxes of hydrogen containing molecules such as methane, water vapor, and molecular hydrogen are the primary source of hydrogen-containing chemical species in the middle and upper atmosphere. Understanding the sensitivity of the thermosphere and exosphere to hydrogenous species distributions below, to sources of natural variability, and to possible long-term climatic changes are central questions for geocoronal research. Observations of thermospheric and exospheric hydrogen-alpha column emissions by the Wisconsin H-alpha Mapper Fabry-Perot (WHAM) over the 1997-2001 rise in the solar cycle are the first Wisconsin-based observations to show a statistically significant solar cyclical variation in the geocoronal H-alpha emission, with higher emissions during solar maximum periods. These observations are scheduled to continue over the decline in the solar cycle, through at least 2005. The WHAM observations corroborate suggestions of such a trend seen in past mid latitude Wisconsin-based H observations. Collectively, this long term, consistently calibrated data record now spans two solar cycles. The research focuses on: analysis of and examination of trends in Fabry-Perot observations of thermospheric and exospheric H intensities; forward modeling retrieval of the thermospheric and exospheric hydrogen column abundance using a global resonance radiative transport code; and comparison of hydrogen column densities retrieved from H observations with those generated using output from a global mean model and the Thermosphere-Ionosphere-Mesosphere Electrodynamics General Circulation Model (TIME-GCM) as input to the radiative transfer code. A primary component to understanding the earth's climate and climate change due to human activities is knowledge of natural variability in the atmosphere. This study contributes to this effort by investigating the influence on upper atmospheric hydrogen of changes in the sun's ultraviolet output over the solar cycle. Upper atmospheric hydrogen is a byproduct of hydrogenous species chemistry in the middle atmosphere, involving molecules such as methane and water vapor, two primary atmospheric greenhouse gases. It is anticipated that characterization of upper atmospheric hydrogen, together with observational diagnostics lower in the atmosphere, will contribute to studies of vertical patterns in hydrogen containing species and their influence upon one another. The WHAM data add to a long-term body of hydrogen emission data now spanning a 20 year period. Their high precision and signal-to-noise facilitate comparisons with past and future data sets. This work will continue current educational and public outreach efforts focused on enhancing scientific literacy concerning climate change and other atmospheric topics, and on promoting diversity in the study of science.

含氢分子（如甲烷、水蒸气和分子氢）的向上通量是中高层大气中含氢化学物种的主要来源。了解热大气层和外逸大气层对下面的含氢物种分布、自然变率的来源以及可能的长期气候变化的敏感性是地冠研究的核心问题。威斯康星州H-阿尔法成像仪Fabry-Perot（WHAM）在1997-2001年太阳活动周期上升期间对热层和外逸层氢-阿尔法柱发射进行的观测，是第一次在威斯康星进行的观测，显示了地冕H-阿尔法发射在统计上的显著太阳活动周期变化，在太阳活动最大期的发射量较高。这些观测计划在太阳活动周期的下降期继续进行，至少到2005年。WHAM的观测结果证实了在过去的中纬度威斯康星州的H观测中看到的这种趋势的建议。总的来说，这个长期的、一致校准的数据记录现在跨越了两个太阳周期。研究重点是：分析和审查热层和外气层氢强度法布里-珀罗观测的趋势;使用全球共振辐射输运代码对热层和外气层氢柱丰度进行前向建模反演;以及从H观测中反演的氢柱密度与使用全球平均模式和热层-电离层-中间层电动力学大气环流模式的输出产生的氢柱密度的比较（TIME-GCM）作为辐射传输代码的输入。了解地球气候和人类活动引起的气候变化的一个主要组成部分是了解大气的自然变化。这项研究有助于这一努力，调查在太阳周期的太阳紫外线输出的变化对高层大气氢的影响。高层大气氢是中层大气含氢物种化学的副产品，涉及甲烷和水蒸气等分子，这两种主要的大气温室气体。预计高层大气氢的表征，以及在大气中较低的观测诊断，将有助于含氢物种的垂直模式及其相互影响的研究。WHAM数据增加了一个长期的氢排放数据，现在跨越20年的时间。其高精度和信噪比便于与过去和未来的数据集进行比较。这项工作将继续目前的教育和公众宣传工作，重点是提高有关气候变化和其他大气专题的科学知识，促进科学研究的多样性。