Nitric oxide abundance in the mesosphere/lower thermosphere region: Roles of solar soft X rays, suprathermal N(4 S) atoms, and vertical transport
Nitric oxide abundance in the mesosphere/lower thermosphere region: Roles of solar soft X rays, suprathermal N(4 S) atoms, and vertical transport
复制标题
中层/下热层区域的一氧化氮丰度：太阳软 X 射线、超热 N(4 S) 原子和垂直传输的作用
DOI：
10.1029/97ja03249
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
J. Duff
中科院分区：
文献类型：
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作者：
P. K. Swaminathan;D. Strobel;D. G. Kupperman;C. K. Kumar;L. Acton;R. DeMajistre;J. Yee;L. Paxton;D. E. Anderson;D. Strickland;J. Duff
本文仔细研究了光化学模型无法解释从IR、UV和微波测量获得的∼108cm−3在∼105kM处的大一氧化氮密度。建立了一个详细和最新的光化学模型，其中包括测量的Yohkoh软X射线通量，热N原子化学与能量相关的热化截面和七个反应源，以及实验室约束的N(2D)产额。与过去的模型相比，所得到的模型的化学成分得到了很好的约束，与最可靠的低热层NO绝对浓度测量相比，它无法产生足够高的NO密度。模型结果的敏感性和投入中的已知不确定性被用来确定今后应将重点放在哪里。尽管低热层的垂直混合率从我们计算中使用的非常低的Kzz剖面增加，和/或电子碰撞解离N(2D)的N(2D)产额从其标称值0.54增加到0.62，但赤字仍然存在。通过用更新的热化截面考虑过热N原子的热化，说明了NO分布对超热N原子大气源新生能量分布的敏感性。当N原子的能量分布选择在0.6 eV或3-4 eV附近时，10 5 km处的日平均NO浓度分别增加了1.2和2.6倍，但∼7和∼3的因子仍然是亏损的.在已知的不确定性范围内，对垂直输运的敏感性高于对化学变化的敏感性。
This paper carefully examines the inability of photochemical models to account for the large nitric oxide densities of ∼108 cm−3 at ∼105 km obtained from IR, UV, and microwave measurements. A detailed and up-to-date photochemical model is constructed that incorporates measured YOHKOH soft X ray fluxes, hot N atom chemistry with an energy dependent thermalization cross section and seven reaction sources, and laboratory-constrained N(2D) yields. The resulting model which has well-constrained chemistry compared to past models fails to generate high enough NO densities in comparison with the most reliable measurements of absolute NO concentrations in the lower thermosphere. The sensitivity of the model results and the known uncertainties in the inputs are used to identify where future efforts should be focused. A deficit remains despite an increase in the vertical mixing rates in the lower thermosphere from the very low Kzz profile used in our calculations and/or an increase in the N(2D) yield from electron impact dissociation of N2 from its nominal value of 0.54 to 0.62. The sensitivity of NO profiles to the nascent energy distributions of the atmospheric sources of suprathermal N atoms is illustrated by including the thermalization of suprathermal N atoms with an updated thermalization cross section. The diurnally averaged NO concentration at 105 km is enhanced by factors of 1.2 and 2.6 when the energy distributions of the N atoms from electron impact dissociation of N2 are chosen with peaks near 0.6 eV or 3–4 eV, but deficits of factors of ∼7 and ∼3, respectively, remain. There is higher sensitivity to vertical transport than to variations of chemistry within known uncertainties.