Observed and modeled solar cycle variation in geocoronal hydrogen using NRLMSISE‐00 thermosphere conditions and the Bishop analytic exosphere model
Observed and modeled solar cycle variation in geocoronal hydrogen using NRLMSISE‐00 thermosphere conditions and the Bishop analytic exosphere model
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使用 NRLMSISE-00 热层条件和 Bishop 分析外逸层模型观测并模拟地冕氢的太阳周期变化
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发表时间：
2012
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通讯作者：
F. Roesler
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作者：
S. Nossal;E. Mierkiewicz;F. Roesler
[1] 使用威斯康星州 H-α 制图仪 (WHAM) 法布里-珀罗在第 23 个太阳周期期间进行高精度观测，量化出接近太阳活动极大值期间的巴尔默 α 柱发射强度比太阳活动极小条件期间高出 1.5 ± 0.15 倍。一个未解决的问题是，观测到的太阳周期氢柱排放变化与根据大气模型中氢分布计算出的变化相比如何？我们将 WHAM 太阳极小值和近太阳极大值柱强度观测结果与使用热层氢密度剖面和质谱仪非相干散射 (NRLMSISE-00) 经验模型的背景热层条件进行的计算进行了比较，该模型使用 Bishop (1991) 的分析外逸层模型扩展到外逸层高度。使用该分布，我们应用 Bishop (1999) 的 lyao_rt 全球共振辐射传输代码来计算在观测观测条件下从地面观测到的预期强度。观测到的强度比相应条件下计算的强度更亮，这表明当使用 MSIS 作为热层氢分布时，导出的强度太低。此外，观测到的和计算出的 WHAM 氢柱发射强度在接近太阳极大值的情况下均高于太阳极小值条件下的 WHAM 氢柱发射强度。观测结果与使用太阳极大期蒸发分析外逸层模型计算的强度之间存在更好的一致性，这表明低估了高海拔卫星原子的模型。这一结果与使用卫星原子准外基选项来解释电荷交换碰撞产生卫星轨道的敏感性研究一致。
[1] High precision observations during Solar Cycle 23 using the Wisconsin H-alpha Mapper (WHAM) Fabry-Perot quantify a factor of 1.5 ± 0.15 higher Balmer α column emission intensity during near-solar-maximum than during solar minimum conditions. An unresolved question is how does the observed solar cycle variation in the hydrogen column emission compare with that calculated from the hydrogen distribution in atmospheric models? We have compared WHAM solar minimum and near-solar-maximum column intensity observations with calculations using the thermospheric hydrogen density profile and background thermospheric conditions from the Mass Spectrometer Incoherent Scatter (NRLMSISE-00) empirical model extended to exospheric altitudes using the analytic exosphere model of Bishop (1991). Using this distribution, we apply the lyao_rt global resonance radiative transfer code of Bishop (1999) to calculate expected intensities that would be observed from the ground for the viewing conditions of the observations. The observed intensities are brighter than those calculated for the corresponding conditions, indicating that when MSIS is used as the thermospheric hydrogen distribution the derived intensities are too low. Additionally, both the observed and calculated WHAM hydrogen column emission intensities are higher for near-solar-maximum than for solar minimum conditions. There is better agreement between observations and intensities calculated using the evaporative analytic exosphere model at solar maximum, suggesting an underestimation of modeled satellite atoms at high altitudes. This result is consistent with sensitivity studies using the option for a quasi-exobase for satellite atoms to account for the creation of satellite orbits from charge exchange collisions.