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

该奖项将使用氢干涉夜光观测和大气环流建模相结合获得的结果，研究从夜间到数十年的各种时间尺度上高层大气氢密度的变化。氢原子密度是热层和外逸层组成的一个关键组成部分，观测氢原子密度的形态和气候学将有助于更好地了解空间天气过程、中性大气等离子体耦合过程以及热层和外逸层上部区域存在的非麦克斯韦物理学。氢也是在较低海拔发生的分子反应的副产品，涉及水蒸气和甲烷等物质，这两种温室气体对地球大气层的能量平衡最重要。因此，跟踪几十年的H密度将提供对中间层区域内发生的任何重大气候变化的洞察。 这些结果将提高对观测到的氢变化的驱动机制的理解，并将确定在观测时间跨度内外大气层氢密度对温室气体增加的反应。该奖项的更广泛影响将包括一名研究生和几名本科生的参与，来自为期两年的威斯康星州校园的一名教师的参与，以及气候科学和高层大气物理学的教育和推广。学生将有机会采取和分析这两个远程天文台的新观测。学生们还将学习使用WACCM-X模型来实现这些比较所需的模拟。应用前向建模方法将比较现有和新的高信噪比法布里-珀罗观测的地冠氢排放与从国家大气研究中心全大气社区气候模型扩展（WACCM-X）的输出中提取的模型模拟。这些数据集将与模式结果相结合，研究现有南半球氢排放观测的变异性，方法是：一旦收集到使用INSpIRe和WHAM法布里-珀罗干涉仪仪器进行的首次重合巴尔默-α观测的南半球和北半球数据，将其变异性与北方半球法布里-珀罗巴尔默-α观测的变异性进行比较。 来自威斯康星州和智利的新观测将提供对NH和SH中纬度氢夜光排放的近乎同时的、仔细校准的测量。该奖项还将用于这项研究的观测来自现有的NH和SH高层大气氢巴尔默α排放数据集。比较这些结果将发现任何半球不对称的氢变化。WACCM-X模拟将通过诊断分析提供有助于Balmer α变异性的机制的调查。最后，将对WACCM-X气候模拟进行分析，以研究含氢成分对温室气体增加的预期反应。该奖项反映了NSF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.