An Explanation for the Nitrous Oxide Layer Observed in the Mesopause Region
An Explanation for the Nitrous Oxide Layer Observed in the Mesopause Region
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DOI：
10.1029/2018gl078895
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发表时间：
2018-08
影响因子：
5.2
通讯作者：
C. Kelly;M. Chipperfield;J. Plane;W. Feng;P. Sheese;K. Walker;C. Boone
中科院分区：
文献类型：
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作者：
C. Kelly;M. Chipperfield;J. Plane;W. Feng;P. Sheese;K. Walker;C. Boone
最近，大气化学实验傅里叶变换光谱仪对中层-低热层（MLT）中一层增强的一氧化二氮（N2O）进行了卫星测量，结果表明存在一个意想不到的小型高空生产源。在这里，我们报告了一种机制的发展和第一个模型模拟，这可以解释 MLT N2O 层的形成。 N2O 的产生主要通过涉及二次电子激发 N2 的反应途径发生。使用整个大气群落气候模型以及全球气辉模型的外部强迫进行模拟，定量地再现了观测到的垂直、纬度和季节性 N2O 变化。灵敏度结果表明，光电子比之前预测的重要得多，MLT 中产生的 N2O 约占全球的三分之二。高纬度地区的高能电子沉淀提供了剩余的贡献。太阳周期分析表明，与太阳活动极小期相比，太阳活动极大期时的 N2O 增强高达 2 倍。
Recent satellite measurements of a layer of enhanced nitrous oxide (N2O) in the mesosphere‐lower thermosphere (MLT) from the Atmospheric Chemistry Experiment‐Fourier Transform Spectrometer have suggested an unexpected, minor high‐altitude production source. Here we report the development of a mechanism and the first model simulations, which can explain the formation of this MLT N2O layer. N2O production occurs primarily via a reaction route involving the excitation of N2 from secondary electrons. Simulations using the Whole Atmosphere Community Climate Model, with external forcing from the Global Airglow model, quantitatively reproduce the observed vertical, latitudinal, and seasonal N2O variations. Sensitivity results indicate that photoelectrons are far more important than previously predicted, causing approximately two thirds of global N2O production in the MLT. Energetic electron precipitation over high latitudes provides the remaining contribution. Solar cycle analysis reveals N2O enhancements of up to ×2 at solar maximum compared to solar minimum.