Theoretical Investigations of OH/HO2 Chemistry in the Middle Atmosphere

在这个项目中，将研究与平流层上层和中层下层的OH/HO2化学有关的一些悬而未决的问题。目前对大气这一区域的HOX化学的理解是复杂的，因为标准的光化学模型或它们的任何修改都不能一致地解释平流层顶上方和下方的奇数氢丰度。这部分是由于决定平流层和中间层中OH/HO2比率的反应的速率系数存在不确定性，或者是由于对HOX化学缺乏充分了解。将研究在平流层和中间层中划分OH/HO2丰度的关键反应，这些反应的速率系数近年来受到了越来越多的关注。振动激发的H_2和O(3P)原子之间的反应的速率系数将被用显式量子力学计算来计算。我们将确定O(3P)原子在中间层中的非热能分布函数，以及它们对O(3P)+H2碰撞生成OH的贡献。此外，还将研究氢原子与臭氧反应产生的振动激发的OH的猝灭。

In this project, a number of outstanding issues related to the OH/HO2 chemistry in the upper stratosphere and lower mesophere will be investigated. Current understanding of the HOx chemistry in this region of the atmosphere is complicated because standard photochemical models or any modifications of them are unable to consistently account for the odd hydrogen abundance above and below the stratopause. This is due, in part, to uncertainties in the rate coefficients of the reactions that determine the OH/HO2 ratio in the stratosphere and mesosphere, and or due to the lack of full understanding of the HOx chemistry. The key reactions that partition the OH/HO2 abundance in the stratosphere and mesosphere whose rate coefficients have come under increased scrutiny in recent years will be investigated. Rate coefficients for the reaction between vibrationally excited H2 and O(3P) atoms which has recently been proposed as a novel source of OH in the mesosphere will be evaluated using explicit quantum mechanical calculations. Nonthermal energy distribution functions of O(3P) atoms in the mesosphere and their contributions to OH formation in O(3P)+H2 collisions will be determined. Further, quenching of vibrationally excited OH produced by the reaction between hydrogen atoms and ozone will be investigated.