CEDAR: Solar Cyclic and Climatic Trends in Geocoronal Hydrogen

该项目的重点是利用威斯康星州中纬度地冕排放的长期记录和NCAR全球平均模式调查太阳循环和地冕氢的气候趋势。这些数据是通过位于威斯康星州和亚利桑那州的两个类似设计的地面法布里-珀罗涉仪获得的。第23太阳周期的高信噪比观测量化了太阳周期对地冕氢柱发射强度的统计显著影响。来自三个太阳极小点(1985、1997、2006)的观测结果在大部分阴影高度范围内符合15%的范围。该项目将继续分析目前跨越三个太阳周期的威斯康星州北半球地冕数据集，以调查太阳周期的影响，并建立更多经过充分校准的数据集，以便将来进行长期比较。该项目包括一项档案研究，通过使用最新的分析技术和来自威斯康星州H-Alpha Mapper Fabry-Perot的最新银河系背景信息，通过重新分析1970-80年代的观测数据，向后扩展威斯康星州的数据集。Roble和Dickinson[1989]的一项开创性研究使用NCAR的中间层、热层和电离层全球平均模式来研究中上层大气对二氧化碳和甲烷加倍的反应。结果表明，甲烷增加一倍，上层热层中的氢气增加了40-50%。此外，还利用全球平均模式对历史上随时间变化的二氧化碳和太阳紫外线通量进行了研究，以研究热层密度对太阳周期和二氧化碳增加的响应。该项目将通过将甲烷的历史浓度添加到全球平均模式来扩展模式研究，以调查在威斯康星州中纬度长期数据集的30年期间预测的太阳循环和热层氢的长期变化的幅度。为了便于将这些模型预测与威斯康星州的观测结果进行比较，全球平均模型的输出将被用作LYAO_RT全球共振辐射传输程序的输入，以将氢密度分布扩展到外层并计算相应的氢柱发射强度。该项目的目标是增加对日地相互作用、长期变化和高层大气耦合的理解。这项研究还将汇编具有高信噪比的观测数据集，用于过去和未来的数据和模型比较。

The focus of the project is to investigate solar cyclic and climatic trends in geocoronal hydrogen using the Wisconsin long-term mid-latitude geocoronal emission record and the NCAR global mean model. The data have been acquired with two similarly designed ground-based Fabry-Perot Interferometers located in Wisconsin and Arizona. High signal-to-noise observations over solar cycle 23 have quantified a statistically significant solar cyclic influence on the geocoronal hydrogen column emission intensity. Observations from three solar minima (1985, 1997, 2006) agree to within 15% over most of the shadow altitude range. This project will continue the analysis of the Wisconsin northern hemisphere geocoronal data set now spanning three solar cycles to investigate solar cycle influences and to establish additional well-calibrated data sets for long-term comparisons into the future. The project includes an archival study to extend the Wisconsin data set backwards through reanalysis of observations taken in the 1970-80s using updated analysis techniques and the most recent Galactic background information from the Wisconsin H-alpha Mapper Fabry-Perot.A seminal study by Roble and Dickinson [1989] used the NCAR global mean model of the mesosphere, thermosphere, and ionosphere to study the response of the middle and upper atmosphere to a doubling of carbon dioxide and methane. The results showed found an increase of 40-50% in upper thermospheric hydrogen in response to a doubling of methane. Additional studies with global mean model were carried out with historical time-dependent values of CO2 and solar UV fluxes to investigate the thermospheric density response to the solar cycle and to CO2 increases. This project will extend the model studies by adding historical concentrations of methane to the global mean model to investigate the magnitude of predicted solar cyclic and secular changes in thermospheric hydrogen over the 30-year period of the Wisconsin long-term mid-latitude data set. In order to facilitate comparison between these model predictions and the Wisconsin observations, output from the global mean model will be used as input to the LYAO_RT global resonance radiative transfer code to extend the hydrogen density profile into the exosphere and to calculate the corresponding hydrogen column emission intensity.The project goal is to increase understanding of solar-terrestrial interactions, long-term variations, and lower-upper atmospheric coupling. The research would also result in the compilation of an observational dataset with high signal-to-noise ratios for past and future data and model comparisons.