Collaborative Research: CEDAR--Upper Atmospheric Hydrogen Variability on Timescales from Dusk-Dawn to Multidecadal

该合同将使用氢干涉夜光观测和一般环流模型相结合获得的结果，研究从夜间到几十年的各种时间尺度上高层大气氢密度的变化。观测原子氢密度（热层和外逸层组成的关键组成部分）的形态和气候学，将有助于更好地理解空间天气过程、中性大气等离子体层耦合过程以及存在于上层热层和外逸层区域的非麦克斯韦物理学。氢也是发生在低海拔地区的分子反应的副产物，包括水蒸气和甲烷这两种对地球大气能量平衡最重要的温室气体。因此，跟踪几十年的H密度将有助于深入了解发生在中间层区域内的任何重大气候变化。这些结果将提高对驱动观测到的氢变率的机制的理解，并将确定在观测时间跨度内外逸层氢密度对温室气体增加的响应。该奖项的广泛影响将包括一名研究生和几名本科生的参与，一名来自威斯康星州两年制校园的教师的参与，以及气候科学和航空科学的教育和推广。学生们将有机会利用这两个远程天文台进行新的观测和分析。学生还将学习使用WACCM-X模型来实现这些比较所需的模拟。正演模拟方法的应用将比较现有的和新的高信噪比Fabry-Perot观测到的日冕氢排放与从国家大气研究中心全大气群落气候模式扩展（WACCM-X）输出中提取的模式模拟结果。一旦利用INSpIRe和WHAM法布里-珀罗干涉仪首次同步观测的南半球和北半球的巴尔默-阿尔法数据收集完成，这些数据集将与模式结果相结合，研究现有南半球（SH）氢发射观测的变化，并将其与北半球（NH）法布里-珀罗巴尔默-阿尔法观测的变化进行比较。来自威斯康辛州和智利的新观测将提供近同时的、精心校准的NH和SH中纬度氢夜光发射测量。该奖项还将利用现有的NH和SH高层大气氢巴尔默α发射数据集的观测结果进行这项研究。比较这些结果将发现任何半球不对称的氢变异性。WACCM-X模拟将通过诊断分析提供对巴尔默α变异机制的研究。最后，将对WACCM-X气候模拟进行分析，研究含氢组分对温室气体增加的预期响应。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award will use results obtained from the combination of hydrogen interferometric nightglow observations and general circulation modeling to study the variability in upper atmospheric hydrogen density over various time scales ranging from night-to-night to multi-decades. Observing the morphology and climatology of atomic hydrogen density, a key constituent in the thermosphere and exosphere composition, will achieve an improved understanding of space-weather processes, neutral atmosphere plasmasphere coupling processes, and non-Maxwellian physics present in the upper thermosphere and exosphere regions. Hydrogen is also a by-product of molecular reactions taking place at lower altitudes involving species such as water vapor and methane, two of the greenhouse gases most important for the energy balance of the Earth’s atmosphere. Thus, tracking the H density over several decades will provide insight into any significant climate change taking place within the mesosphere region. These results will improve the understanding of the mechanisms driving the observed hydrogen variability and will determine the response of exospheric hydrogen density to increases in greenhouse gases over the time span of observations. Broader impacts of this award will include involvement of one graduate student as well as several undergraduate students, participation by a faculty member from a two-year Wisconsin campus, as well as education and outreach in climate science and aeronomy. Students will have the opportunity to take and analyze new observations with these two remote observatories. The students will also learn the use of the WACCM-X model to achieve the simulations necessary for these comparisons.Application of forward modeling methodology will compare existing and new high signal-to-noise Fabry-Perot observations of geocoronal hydrogen emissions with model simulations extracted from the outputs of the National Center for Atmospheric Research Whole Atmosphere Community Climate Model eXtended (WACCM-X). These data sets would be combined with the model results to study the variability in existing Southern Hemisphere (SH) hydrogen emission observations by comparing its variations to that observed for the Northern Hemisphere (NH) Fabry-Perot Balmer-alpha observations once the SH and NH data for the first coincident Balmer-alpha observations using the INSpIRe and WHAM Fabry-Perot interferometer instruments have been collected. The new observations from Wisconsin and Chile will provide near-simultaneous, carefully-calibrated measurements of hydrogen nightglow emissions from NH and SH mid-latitudes. The award will also use for this study the observations drawn from existing NH and SH upper atmospheric hydrogen Balmer alpha emission data sets. Comparing these results will detect any hemispheric asymmetries in hydrogen variability. WACCM-X simulations will provide for the investigation of mechanisms contributing to Balmer alpha variability through diagnostic analysis. Finally, WACCM-X climate simulations will be analyzed to study the expected response of hydrogen-containing constituents to increases in greenhouse gases.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.